Refereed Publications with Abstracts

MOPITT Refereed Publications

2018 | 2017 | 2016 | 2015 | 2014 | 2013 | 2012 | 2011 | 2010 | 2009 | 2008 | 2007 | 2006 | 2005 | 2004 | 2003 | 2002 | 2001 | 2000 | 1999 | 1998 | 1997 | 1996 | 1995

Publication Count by Year

2018

Aliyu, Y. A., and J. O. Botai (2018), Appraising city-scale pollution monitoring capabilities of multi-satellite datasets using portable pollutant monitors, Atmospheric Environment, 179, 239–249, doi:10.1016/j.atmosenv.2018.02.034.
The retrieval characteristics for a city-scale satellite experiment was explored over a Nigerian city. The study evaluated carbon monoxide and aerosol contents in the city atmosphere. We utilized the MSA Altair 5× gas detector and CW-HAT200 particulate counter to investigate the city-scale monitoring capabilities of satellite pollution observing instruments; atmospheric infrared sounder (AIRS), measurement of pollution in the troposphere (MOPITT), moderate resolution imaging spectroradiometer (MODIS), multi-angle imaging spectroradiometer (MISR) and ozone monitoring instrument (OMI). To achieve this, we employed the Kriging interpolation technique to collocate the satellite pollutant estimations over 19 ground sample sites for the period of 2015–2016. The portable pollutant devices were validated using the WHO air filter sampling model. To determine the city-scale performance of the satellite datasets, performance indicators: correlation coefficient, model efficiency, reliability index and root mean square error, were adopted as measures. The comparative analysis revealed that MOPITT carbon monoxide (CO) and MODIS aerosol optical depth (AOD) estimates are the appropriate satellite measurements for ground equivalents in Zaria, Nigeria. Our findings were within the acceptable limits of similar studies that utilized reference stations. In conclusion, this study offers direction to Nigeria’s air quality policy organizers about available alternative air pollution measurements for mitigating air quality effects within its limited resource environment.
Aragão, L. E. O. C., L. O. Anderson, M. G. Fonseca, T. M. Rosan, L. B. Vedovato, F. H. Wagner, C. V. J. Silva, C. H. L. S. Junior, E. Arai, A. P. Aguiar, J. Barlow, E. Berenguer, M. N. Deeter, L. G. Domingues, L. Gatti, M. Gloor, Y. Malhi, J. A. Marengo, J. B. Miller, O. L. Phillips, and S. Saatchi (2018), 21st Century drought-related fires counteract the decline of Amazon deforestation carbon emissions, Nature Communications, 9(1), 536, doi:10.1038/s41467-017-02771-y.
Deforestation carbon emissions from the Brazilian Amazon have declined steeply, but how much drought-induced forest fire emissions add to this process is still unclear. Here the authors show that gross emissions from forest fires are more than half as great as those from deforestation during drought years.
Edwards, D. P., H. M. Worden, D. Neil, G. Francis, T. Valle, and A. F. Arellano (2018), The CHRONOS mission: capability for sub-hourly synoptic observations of carbon monoxide and methane to quantify emissions and transport of air pollution, Atmos. Meas. Tech., 11(2), 1061–1085, doi:10.5194/amt-11-1061-2018.
The CHRONOS space mission concept provides time-resolved abundance for emissions and transport studies of the highly variable and highly uncertain air pollutants carbon monoxide and methane, with sub-hourly revisit rate at fine (similar to 4 km) horizontal spatial resolution across a North American domain. CHRONOS can provide complete synoptic air pollution maps (“snapshots”) of the continental domain with less than 10 min of observations. This rapid mapping enables visualization of air pollution transport simultaneously across the entire continent and enables a sentinel-like capability for monitoring evolving, or unanticipated, air pollution sources in multiple locations at the same time with high temporal resolution. CHRONOS uses a compact imaging gas filter correlation radiometer for these observations, with heritage from more than 17 years of scientific data and algorithm advances by the science teams for the Measurements of Pollution in the Troposphere (MOPITT) instrument on NASA’s Terra spacecraft in low Earth orbit. To achieve continental-scale sub-hourly sampling, the CHRONOS mission would be conducted from geostationary orbit, with the instrument hosted on a communications or meteorological platform. CHRONOS observations would contribute to an integrated observing system for atmospheric composition using surface, suborbital and satellite data with atmospheric chemistry models, as defined by the Committee on Earth Observing Satellites. Addressing the U.S. National Academy’s 2007 decadal survey direction to characterize diurnal changes in tropospheric composition, CHRONOS observations would find direct societal applications for air quality management and forecasting to protect public health.
Muller, J.-F., T. Stavrakou, M. Bauwens, M. George, D. Hurtmans, P.-F. Coheur, C. Clerbaux, and C. Sweeney (2018), Top-Down CO Emissions Based On IASI Observations and Hemispheric Constraints on OH Levels, Geophys. Res. Lett., 45(3), 1621–1629, doi:10.1002/2017GL076697.
Assessments of carbon monoxide emissions through inverse modeling are dependent on the modeled abundance of the hydroxyl radical (OH) which controls both the primary sink of CO and its photochemical source through hydrocarbon oxidation. However, most chemistry transport models (CTMs) fall short of reproducing constraints on hemispherically averaged OH levels derived from methylchloroform (MCF) observations. Here we construct five different OH fields compatible with MCF-based analyses, and we prescribe those fields in a global CTM to infer CO fluxes based on Infrared Atmospheric Sounding Interferometer (IASI) CO columns. Each OH field leads to a different set of optimized emissions. Comparisons with independent data (surface, ground-based remotely sensed, aircraft) indicate that the inversion adopting the lowest average OH level in the Northern Hemisphere (7.8 x 10(5) molec cm(-3), approximate to 18% lower than the best estimate based on MCF measurements) provides the best overall agreement with all tested observation data sets.
Palve, S. N., P. D. Nemade, and S. D. Ghude (2018), MOPITT carbon monoxide its source distributions, interannual variability and transport pathways over India during 2005-2015, International Journal of Remote Sensing, 0(0), 1–13, doi:10.1080/01431161.2018.1452076.
Rapid industrial and economic development over the past two decades in India leads the high levels of air pollution. Carbon monoxide (CO) is one of the main pollutants, is not only harmful for human beings but also for its impact on climate. The major CO sources in India are biomass burning and vehicular emissions. Here we used Measurement of Pollution in the Troposphere (MOPITT) CO data from 2005–2015 to examine CO sources, interannual variability, and transport pathways over India. We observed that during the winter months CO emissions over eastern part of Bihar, west Bengal and Northern Indo Gangetic (IG) plain are much higher than during the summer months. The increased vehicular emissions and industrial activity after 2010 resulted in increased CO in the same regions. CO mixing ratios at 350 hPa lowered at 68–90 µg m−3 over Arabian Sea and approximately 90 µg m−3 over Bay of Bengal during Indian summer monsoon. Deep convective activities transported maximum CO pollutants up to 200 µg m−3 over northern and eastern part of India during monsoon season.
Zheng, B., F. Chevallier, P. Ciais, Y. Yin, M. N. Deeter, H. M. Worden, Y. Wang, Qiang Zhang, and K. He (2018), Rapid decline in carbon monoxide emissions and export from East Asia between years 2005 and 2016, Environ. Res. Lett., 13(4), 044007, doi:10.1088/1748-9326/aab2b3.
Measurements of Pollution in the Troposphere (MOPITT) satellite and ground-based carbon monoxide (CO) measurements both suggest a widespread downward trend in CO concentrations over East Asia during the period 2005–2016. This negative trend is inconsistent with global bottom-up inventories of CO emissions, which show a small increase or stable emissions in this region. We try to reconcile the observed CO trend with emission inventories using an atmospheric inversion of the MOPITT CO data that estimates emissions from primary sources, secondary production, and chemical sinks of CO. The atmospheric inversion indicates a −2% yr −1 decrease in emissions from primary sources in East Asia from 2005–2016. The decreasing emissions are mainly caused by source reductions in China. The regional MEIC inventory for China is the only bottom up estimate consistent with the inversion-diagnosed decrease of CO emissions. According to the MEIC data, decreasing CO emissions from four main sectors (iron and steel industries, residential sources, gasoline-powered vehicles, and construction materials industries) in China explain 76% of the inversion-based trend of East Asian CO emissions. This result suggests that global inventories underestimate the recent decrease of CO emission factors in China which occurred despite increasing consumption of carbon-based fuels, and is driven by rapid technological changes with improved combustion efficiency and emission control measures.

2017

Andela, N., D. C. Morton, L. Giglio, Y. Chen, G. R. van der Werf, P. S. Kasibhatla, R. S. DeFries, G. J. Collatz, S. Hantson, S. Kloster, D. Bachelet, M. Forrest, G. Lasslop, F. Li, S. Mangeon, J. R. Melton, C. Yue, and J. T. Randerson (2017), A human-driven decline in global burned area, Science, 356(6345), 1356–1362, doi:10.1126/science.aal4108.
Fire is an essential Earth system process that alters ecosystem and atmospheric composition. Here we assessed long-term fire trends using multiple satellite data sets. We found that global burned area declined by 24.3 ± 8.8% over the past 18 years. The estimated decrease in burned area remained robust after adjusting for precipitation variability and was largest in savannas. Agricultural expansion and intensification were primary drivers of declining fire activity. Fewer and smaller fires reduced aerosol concentrations, modified vegetation structure, and increased the magnitude of the terrestrial carbon sink. Fire models were unable to reproduce the pattern and magnitude of observed declines, suggesting that they may overestimate fire emissions in future projections. Using economic and demographic variables, we developed a conceptual model for predicting fire in human-dominated landscapes. Global burned area has declined by ~25% over the past 18 years. Global burned area has declined by ~25% over the past 18 years.
Badia, A., O. Jorba, A. Voulgarakis, D. Dabdub, C. P. Garcia-Pando, A. Hilboll, M. Goncalves, and Z. Janjic (2017), Description and Evaluation of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry Model (NMMB-MONARCH) Version 1.0: Gas-Phase Chemistry at Global Scale, Geoscientific Model Development, 10(2), 609–638, doi:10.5194/gmd-10-609-2017.
This paper presents a comprehensive description and benchmark evaluation of the tropospheric gas-phase chemistry component of the Multiscale Online Nonhydrostatic AtmospheRe CHemistry model , formerly known as NMMB/BSC-CTM, that can be run on both regional and global domains. Here, we provide an extensive evaluation of a global annual cycle simulation using a variety of background surface stations , ozonesondes , aircraft data , and satellite observations .We also include an extensive discussion of our results in comparison to other state-of-the-art models. We note that in this study, we omitted aerosol processes and some natural emissions . The model shows a realistic oxidative capacity across the globe. The seasonal cycle for CO is fairly well represented at different locations , although concentrations are underestimated in spring and winter in the Northern Hemisphere, and are overestimated throughout the year at 800 and 500 hPa in the Southern Hemisphere. Nitrogen species are well represented in almost all locations, particularly NO2 in Europe . The modeled vertical distributions of NOx and HNO3 are in excellent agreement with the observed values and the spatial and seasonal trends of tropospheric NO2 columns correspond well to observations from SCIAMACHY, capturing the highly polluted areas and the biomass burning cycle throughout the year. Over Asia, the model underestimates NOx from March to August, probably due to an underestimation of NOx emissions in the region. Overall, the comparison of the modeled CO and NO2 with MOPITT and SCIAMACHY observations emphasizes the need for more accurate emission rates from anthropogenic and biomass burning sources .
Borsdorff, T., J. A. de Brugh, H. Hu, P. Nedelec, I. Aben, and J. Landgraf (2017), Carbon monoxide column retrieval for clear-sky and cloudy atmospheres: a full-mission data set from SCIAMACHY 2.3 mu m reflectance measurements, Atmos. Meas. Tech., 10(5), 1769–1782, doi:10.5194/amt-10-1769-2017.
We discuss the retrieval of carbon monoxide (CO) vertical column densities from clear-sky and cloud contaminated 2311-2338 nm reflectance spectra measured by the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) from January 2003 until the end of the mission in April 2012. These data were processed with the Shortwave Infrared CO Retrieval algorithm (SICOR) that we developed for the operational data processing of the Tropospheric Monitoring Instrument (TROPOMI) that will be launched on ESA’s Sentinel-5 Precursor (S5P) mission. This study complements previous work that was limited to clear-sky observations over land. Over the oceans, CO is estimated from cloudy-sky measurements only, which is an important addition to the SCIAMACHY clear-sky CO data set as shown by NDACC and TCCON measurements at coastal sites. For Ny-Alesund, Lauder, Mauna Loa and Reunion, a validation of SCIAMACHY clear-sky retrievals is not meaningful because of the high retrieval noise and the few collocations at these sites. The situation improves significantly when considering cloudy-sky observations, where we find a low mean bias (b) over bar = +/- 6.0 ppb and a strong correlation between the validation and the SCIAMACHY results with a mean Pearson correlation coefficient r = 0.7. Also for land observations, cloudy-sky CO retrievals present an interesting complement to the clear-sky data set. For example, at the cities Tehran and Beijing the agreement of SCIAMACHY clear-sky CO observations with MOZAIC/IAGOS airborne measurements is poor with a mean bias of (b) over bar = 171.2 ppb and 57.9 ppb because of local CO pollution, which cannot be captured by SCIAMACHY. For cloudy-sky retrievals, the validation improves significantly. Here the retrieved column is mainly sensitive to CO above the cloud and so not affected by the strong local surface emissions. Adjusting the MOZAIC/IAGOS measurements to the vertical sensitivity of the retrieval, the mean bias adds up to (b) over bar = 52.3 ppb and 5.0 ppb for Tehran and Beijing. At the less urbanised region around the airport Windhoek, local CO pollution is less prominent and so MOZAIC/IAGOS measurements agree well with SCIAMACHY clear-sky retrievals with a mean bias of (b) over bar = 15.5 ppb, but can be even further improved for cloudy SCIAMACHY observations with a mean bias of (b) over bar = 0.2 ppb. Overall the cloudy-sky CO retrievals from SCIA-MACHY short-wave infrared measurements present a major extension of the clear-sky-only data set, which more than triples the amount of data and adds unique observations over the oceans. Moreover, the study represents the first application of the S5P algorithm for operational CO data processing on cloudy observations prior to the launch of the S5P mission.
Buchholz, R. R., M. N. Deeter, H. M. Worden, J. Gille, D. P. Edwards, J. W. Hannigan, N. B. Jones, C. Paton-Walsh, D. W. T. Griffith, D. Smale, J. Robinson, K. Strong, S. Conway, R. Sussmann, F. Hase, T. Blumenstock, E. Mahieu, and B. Langerock (2017), Validation of MOPITT carbon monoxide using ground-based Fourier transform infrared spectrometer data from NDACC, Atmos. Meas. Tech., 10(5), 1927–1956, doi:10.5194/amt-10-1927-2017.
The Measurements of Pollution in the Troposphere (MOPITT) satellite instrument provides the longest continuous dataset of carbon monoxide (CO) from space. We perform the first validation of MOPITT version 6 retrievals using total column CO measurements from ground-based remote-sensing Fourier transform infrared spectrometers (FTSs). Validation uses data recorded at 14 stations, that span a wide range of latitudes (80 degrees N to 78 degrees S), in the Network for the Detection of Atmospheric Composition Change (NDACC). MOPITT measurements are spatially co-located with each station, and different vertical sensitivities between instruments are accounted for by using MOPITT averaging kernels (AKs). All three MOPITT retrieval types are analyzed: thermal infrared (TIR-only), joint thermal and near infrared (TIR-NIR), and near infrared (NIR-only). Generally, MOPITT measurements overestimate CO relative to FTS measurements, but the bias is typically less than 10 %. Mean bias is 2.4% for TIR-only, 5.1% for TIR-NIR, and 6.5% for NIR-only. The TIR-NIR and NIR-only products consistently produce a larger bias and lower correlation than the TIR-only. Validation performance of MOPITT for TIR-only and TIR-NIR retrievals over land or water scenes is equivalent. The four MOPITT detector element pixels are validated separately to account for their different uncertainty characteristics. Pixel 1 produces the highest standard deviation and lowest correlation for all three MOPITT products. However, for TIR-only and TIR-NIR, the error-weighted average that includes all four pixels often provides the best correlation, indicating compensating pixel biases and well-captured error characteristics. We find that MOPITT bias does not depend on latitude but rather is influenced by the proximity to rapidly changing atmospheric CO. MOPITT bias drift has been bound geographically to within +/- 0.5% yr 1 or lower at almost all locations.
Chatterjee, A., M. M. Gierach, A. J. Sutton, R. A. Feely, D. Crisp, A. Eldering, M. R. Gunson, C. W. O’Dell, B. B. Stephens, and D. S. Schimel (2017), Influence of El Niño on atmospheric CO2 over the tropical Pacific Ocean: Findings from NASA’s OCO-2 mission, Science, 358(6360), eaam5776, doi:10.1126/science.aam5776.
Structured Abstract INTRODUCTIONThe Orbiting Carbon Observatory-2 (OCO-2) is NASA’s first satellite designed to measure atmospheric carbon dioxide (CO2) with the precision, resolution, and coverage necessary to quantify regional carbon sources and sinks. OCO-2 launched on 2 July 2014, and during the first 2 years of its operation, a major El Niño occurred: the 2015–2016 El Niño, which was one of the strongest events ever recorded.El Niño and its cold counterpart La Niña (collectively known as the El Niño–Southern Oscillation or ENSO) are the dominant modes of tropical climate variability. ENSO originates in the tropical Pacific Ocean but spurs a variety of anomalous weather patterns around the globe. Not surprisingly, it also leaves an imprint on the global carbon cycle. Understanding the magnitude and phasing of the ENSO-CO2 relationship has important implications for improving the predictability of carbon-climate feedbacks.The high-density observations from NASA’s OCO-2 mission, coupled with surface ocean CO2 measurements from NOAA buoys, have provided us with a unique data set to track the atmospheric CO2 concentrations and unravel the timing of the response of the ocean and the terrestrial carbon cycle during the 2015–2016 El Niño. RATIONALEDuring strong El Niño events, there is an overall increase in global atmospheric CO2 concentrations. This increase is predominantly due to the response of the terrestrial carbon cycle to El Niño–induced changes in weather patterns. But along with the terrestrial component, the tropical Pacific Ocean also plays an important role. Typically, the tropical Pacific Ocean is a source of CO2 to the atmosphere due to equatorial upwelling that brings CO2-rich water from the interior ocean to the surface. During El Niño, this equatorial upwelling is suppressed in the eastern and the central Pacific Ocean, reducing the supply of CO2 to the surface. If CO2 fluxes were to remain constant elsewhere, this reduction in ocean-to-atmosphere CO2 fluxes should contribute to a slowdown in the growth of atmospheric CO2. This hypothesis cannot be verified, however, without large-scale CO2 observations over the tropical Pacific Ocean. RESULTSOCO-2 observations confirm that the tropical Pacific Ocean played an early and important role in the response of atmospheric CO2 concentrations to the 2015–2016 El Niño. By analyzing trends in the time series of atmospheric CO2, we see clear evidence of an initial decrease in atmospheric CO2 concentrations over the tropical Pacific Ocean, specifically during the early stages of the El Niño event (March through July 2015). Atmospheric CO2 concentration anomalies suggest a flux reduction of 26 to 54% that is validated by the NOAA Tropical Atmosphere Ocean (TAO) mooring CO2 data. Both the OCO-2 and TAO data further show that the reduction in ocean-to-atmosphere fluxes is spatially variable and has strong gradients across the tropical Pacific Ocean.During the later stages of the El Niño (August 2015 and later), the OCO-2 observations register a rise in atmospheric CO2 concentrations. We attribute this increase to the response from the terrestrial component of the carbon cycle—a combination of reduction in biospheric uptake of CO2 over pan-tropical regions and an enhancement in biomass burning emissions over Southeast Asia and Indonesia. The net impact of the 2015–2016 El Niño event on the global carbon cycle is an increase in atmospheric CO2 concentrations, which would likely be larger if it were not for the reduction in outgassing from the ocean. CONCLUSIONThe strong El Niño event of 2015–2016 provided us with an opportunity to study how the global carbon cycle responds to a change in the physical climate system. Space-based observations of atmospheric CO2, such as from OCO-2, allow us to observe and monitor the temporal sequence of El Niño–induced changes in CO2 concentrations. Disentangling the timing of the ocean and terrestrial responses is the first step toward interpreting their relative contribution to the global atmospheric CO2 growth rate, and thereby understanding the sensitivity of the carbon cycle to climate forcing on interannual to decadal time scales. <img class="fragment-image" src="https://d2ufo47lrtsv5s.cloudfront.net/content/sci/358/6360/eaam5776/F1.medium.gif"/> Download high-res image Open in new tab Download Powerpoint NASA’s carbon sleuth tracks the influence of El Niño on atmospheric CO2.The tropical Pacific Ocean, the center of action during an El Niño event, is shown in cross section. Warm ocean surface temperatures are shown in red, cooler waters in blue. The Niño 3.4 region, which scientists use to study the El Niño, is denoted by yellow dashed lines. As a result of OCO-2’s global coverage and 16-day repeat cycle, it flies over the entire region every few days, keeping tabs on the changes in atmospheric CO2 concentration. Spaceborne observations of carbon dioxide (CO2) from the Orbiting Carbon Observatory-2 are used to characterize the response of tropical atmospheric CO2 concentrations to the strong El Niño event of 2015–2016. Although correlations between the growth rate of atmospheric CO2 concentrations and the El Niño–Southern Oscillation are well known, the magnitude of the correlation and the timing of the responses of oceanic and terrestrial carbon cycle remain poorly constrained in space and time. We used space-based CO2 observations to confirm that the tropical Pacific Ocean does play an early and important role in modulating the changes in atmospheric CO2 concentrations during El Niño events—a phenomenon inferred but not previously observed because of insufficient high-density, broad-scale CO2 observations over the tropics.
Deeter, M. N., D. P. Edwards, G. L. Francis, J. C. Gille, S. Martinez-Alonso, H. M. Worden, and C. Sweeney (2017), A Climate-scale Satellite Record for Carbon Monoxide: The MOPITT Version 7 Product, Atmos. Meas. Tech. Discuss., 2017, 1–34, doi:10.5194/amt-2017-71.
The MOPITT (“Measurements of Pollution in the Troposphere”) satellite instrument has been making observations of atmospheric carbon monoxide since 2000. Recent enhancements to the MOPITT retrieval algorithm have resulted in the release of the Version 7 (V7) product. Improvements include (1) representation of growing atmospheric concentrations of N2O, (2) use of meteorological fields from the MERRA-2 reanalysis for the entire MOPITT mission (instead of MERRA), (3) use of the MODIS Collection 6 cloud mask product (instead of Collection 5), (4) a new strategy for radiance bias correction, and (5) an improved method for calibrating MOPITT’s NIR radiances. Statistical comparisons of V7 validation results with corresponding V6 results are presented, using aircraft in-situ measurements as the reference. Clear improvements are demonstrated for V7 products with respect to overall retrieval biases, bias variability, and bias drift uncertainty.
Dekker, I. N., S. Houweling, I. Aben, T. Röckmann, M. Krol, S. Martínez-Alonso, M. N. Deeter, and H. M. Worden (2017), Quantification of CO emissions from the city of madrid using MOPITT satellite retrievals and WRF simulations, Atmospheric Chemistry and Physics, 17(23), 14675–14694, doi:10.5194/acp-17-14675-2017.
<p>The growth of mega-cities leads to air quality problems directly affecting the citizens. Satellite measurements are becoming of higher quality and quantity, which leads to more accurate satellite retrievals of enhanced air pollutant concentrations over large cities. In this paper, we compare and discuss both an existing and a new method for estimating urban-scale trends in CO emissions using multiyear retrievals from the MOPITT satellite instrument. The first method is mainly based on satellite data, and has the advantage of fewer assumptions, but also comes with uncertainties and limitations as shown in this paper. To improve the reliability of urban-To-regional scale emission trend estimation, we simulate MOPITT retrievals using the Weather Research and Forecast model with chemistry core (WRFChem). The difference between model and retrieval is used to optimize CO emissions in WRF-Chem, focusing on the city of Madrid, Spain. This method has the advantage over the existing method in that it allows both a trend analysis of CO concentrations and a quantification of CO emissions. Our analysis confirms that MOPITT is capable of detecting CO enhancements over Madrid, although significant differences remain between the yearly averaged model output and satellite measurements (R2 D0.75) over the city. After optimization, we find Madrid CO emissions to be lower by 48% for 2002 and by 17% for 2006 compared with the EdgarV4.2 emission inventory. The MOPITT-derived emission adjustments lead to better agreement with the European emission inventory TNO-MAC-III for both years. This suggests that the downward trend in CO emissions over Madrid is overestimated in EdgarV4.2 and more realistically represented in TNO-MACC-III. However, our satellite and model based emission estimates have large uncertainties, around 20% for 2002 and 50% for 2006.</p>
Eldering, A., P. O. Wennberg, D. Crisp, D. S. Schimel, M. R. Gunson, A. Chatterjee, J. Liu, F. M. Schwandner, Y. Sun, C. W. O’Dell, C. Frankenberg, T. Taylor, B. Fisher, G. B. Osterman, D. Wunch, J. Hakkarainen, J. Tamminen, and B. Weir (2017), The Orbiting Carbon Observatory-2 early science investigations of regional carbon dioxide fluxes, Science, 358(6360), eaam5745, doi:10.1126/science.aam5745.
Structured Abstract INTRODUCTIONEarth’s carbon cycle involves large fluxes of carbon dioxide (CO2) between the atmosphere, land biosphere, and oceans. Over the past several decades, net loss of CO2 from the atmosphere to the land and oceans has varied considerably from year to year, equaling 20 to 80% of CO2 emissions from fossil fuel combustion and land use change. On average, the uptake is about 50%. The imbalance between CO2 emissions and removal is seen in increasing atmospheric CO2 concentrations. In recent years, an increase of 2 to 3 parts per million (ppm) per year in the atmospheric mole fraction, which is currently about 400 ppm, has been observed.Almost a quarter of the CO2 emitted by human activities is being absorbed by the ocean, and another quarter is absorbed by processes on land. The identity and location of the terrestrial sinks are poorly understood. This absorption has been attributed by some to tropical or Eurasian temperate forests, whereas others argue that these regions may be net sources of CO2. The efficiency of these land sinks appears to vary dramatically from year to year. Because the identity, location, and processes controlling these natural sinks are not well constrained, substantial additional uncertainty is added to projections of future CO2 levels. RATIONALEThe NASA satellite, the Orbiting Carbon Observatory-2 (OCO-2), which was launched on 2 July 2014, is designed to collect global measurements with sufficient precision, coverage, and resolution to aid in resolving sources and sinks of CO2 on regional scales. Since 6 September 2014, the OCO-2 mission has been producing about 2 million estimates of the column-averaged CO2 dry-air mole fraction (<img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-1.gif"/>) each month after quality screening, with spatial resolution of <3 km2 per sounding. Solar-induced chlorophyll fluorescence (SIF), a small amount of light emitted during photosynthesis, is detected in remote sensing measurements of radiance within solar Fraunhofer lines and is another data product from OCO-2. RESULTSThe measurements from OCO-2 provide a global view of the seasonal cycles and spatial patterns of atmospheric CO2, with the anticipated year-over-year growth rate. The buildup of CO2 in the Northern Hemisphere during winter and its rapid decrease in concentration as spring arrives (and the SIF increases) is seen in unprecedented detail. The enhanced CO2 in urban areas relative to nearby background areas is observed with a single overpass of OCO-2. Increases in CO2 due to the biomass burning in Africa are also clearly observed. The dense, global, <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-2.gif"/> and SIF data sets from OCO-2 are combined with other remote sensing data sets and used to disentangle the processes driving the carbon cycle on regional scales during the recent 2015–2016 El Niño event. This analysis shows more carbon release in 2015 relative to 2011 over Africa, South America, and Southeast Asia. Now, the fundamental driver for the change in carbon release can be assessed continent by continent, rather than treating the tropics as a single, integrated region. Small changes in <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-3.gif"/> were also observed early in the El Niño over the equatorial eastern Pacific, due to less upwelling of cold, carbon-rich water than is typical. CONCLUSIONNASA’s OCO-2 mission is collecting a dense, global set of high-spectral resolution measurements that are used to estimate <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-4.gif"/> and SIF. The OCO-2 mission data set can now be used to assess regional-scale sources and sinks of CO2 around the globe. The papers in this collection present early scientific findings from this new data set. <img class="fragment-image" src="https://d2ufo47lrtsv5s.cloudfront.net/content/sci/358/6360/eaam5745/F1.medium.gif"/> Download high-res image Open in new tab Download Powerpoint El Niño impact on carbon flux in 2015 relative to 2011, detected from Greenhouse Gases Observing Satellite (GOSAT) and OCO-2 data.OCO-2 uses reflected sunlight to derive <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/F1/embed/mml-math-5.gif"/> and SIF. This shows OCO-2 <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/F1/embed/mml-math-6.gif"/> data over North America from 12 August 2015 to 26 August 2015. NASA’s Orbiting Carbon Observatory-2 (OCO-2) mission was motivated by the need to diagnose how the increasing concentration of atmospheric carbon dioxide (CO2) is altering the productivity of the biosphere and the uptake of CO2 by the oceans. Launched on 2 July 2014, OCO-2 provides retrievals of the column-averaged CO2 dry-air mole fraction (<img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-7.gif"/>) as well as the fluorescence from chlorophyll in terrestrial plants. The seasonal pattern of uptake by the terrestrial biosphere is recorded in fluorescence and the drawdown of <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-8.gif"/> during summer. Launched just before one of the most intense El Niños of the past century, OCO-2 measurements of <img class="highwire-embed" alt="Embedded Image" src="https://d2ufo47lrtsv5s.cloudfront.net/sites/default/files/highwire/sci/358/6360/eaam5745/embed/mml-math-9.gif"/> and fluorescence record the impact of the large change in ocean temperature and rainfall on uptake and release of CO2 by the oceans and biosphere.
Gaubert, B., H. M. Worden, A. F. J. Arellano, L. K. Emmons, S. Tilmes, J. Barre, S. M. Alonso, F. Vitt, J. L. Anderson, F. Alkemade, S. Houweling, and D. P. Edwards (2017), Chemical Feedback From Decreasing Carbon Monoxide Emissions, Geophys. Res. Lett., 44(19), 9985–9995, doi:10.1002/2017GL074987.
Understanding changes in the burden and growth rate of atmospheric methane (CH4) has been the focus of several recent studies but still lacks scientific consensus. Here we investigate the role of decreasing anthropogenic carbon monoxide (CO) emissions since 2002 on hydroxyl radical (OH) sinks and tropospheric CH4 loss. We quantify this impact by contrasting two model simulations for 2002-2013: (1) a Measurement of the Pollution in the Troposphere (MOPITT) CO reanalysis and (2) a Control-Run without CO assimilation. These simulations are performed with the Community Atmosphere Model with Chemistry of the Community Earth System Model fully coupled chemistry climate model with prescribed CH4 surface concentrations. The assimilation of MOPITT observations constrains the global CO burden, which significantly decreased over this period by similar to 20%. We find that this decrease results to (a) increase in CO chemical production, (b) higher CH4 oxidation by OH, and (c) similar to 8% shorter CH4 lifetime. We elucidate this coupling by a surrogate mechanism for CO-OH-CH4 that is quantified from the full chemistry simulations.
Jiang, Z., J. R. Worden, H. Worden, M. Deeter, D. B. A. Jones, A. F. Arellano, and D. K. Henze (2017), A 15-year record of CO emissions constrained by MOPITT CO observations, Atmos. Chem. Phys., 17(7), 4565–4583, doi:10.5194/acp-17-4565-2017.
Long-term measurements from satellites and surface stations have demonstrated a decreasing trend of tropospheric carbon monoxide (CO) in the Northern Hemisphere over the past decade. Likely explanations for this decrease include changes in anthropogenic, fires, and/or biogenic emissions or changes in the primary chemical sink hydroxyl radical (OH). Using remotely sensed CO measurements from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument, in situ methyl chloroform (MCF) measurements from the World Data Centre for Greenhouse Gases (WDCGG) and the adjoint of the GEOS-Chem model, we estimate the change in global CO emissions from 2001 to 2015. We show that the loss rate of MCF varied by 0.2 % in the past 15 years, indicating that changes in global OH distributions do not explain the recent decrease in CO. Our two-step inversion approach for estimating CO emissions is intended to mitigate the effect of bias errors in the MOPITT data as well as model errors in transport and chemistry, which are the primary factors contributing to the uncertainties when quantifying CO emissions using these remotely sensed data. Our results confirm that the decreasing trend of tropospheric CO in the Northern Hemisphere is due to decreasing CO emissions from anthropogenic and biomass burning sources. In particular, we find decreasing CO emissions from the United States and China in the past 15 years, and unchanged anthropogenic CO emissions from Europe since 2008. We find decreasing trends of biomass burning CO emissions from boreal North America, boreal Asia and South America, but little change over Africa. In contrast to prior results, we find that a positive trend in CO emissions is likely for India and southeast Asia.
Khan, A., J. E. Szulejko, M.-S. Bae, Z. H. Shon, J.-R. Sohn, J. W. Seo, E.-C. Jeon, and K.-H. Kim (2017a), Long-term trend analysis of CO in the Yongsan district of Seoul, Korea, between the years 1987 and 2013, Atmospheric Pollution Research, doi:10.1016/j.apr.2017.03.006. [online] Available from: http://www.sciencedirect.com/science/article/pii/S1309104217300995 .
In this study, the long-term trend in atmospheric carbon monoxide (CO) concentration was analyzed using the CO levels measured (intermittently) at an air quality monitoring (AQM) station in Seoul, Korea, between the years 1987 and 2013. Temporal trends in CO were analyzed on an annual and seasonal basis in reference to other important air pollutants such as methane (CH4), particulate matter (PM10), sulfur dioxide (SO2), nitrogen monoxide (NO), nitrogen dioxide (NO2), mercury (Hg), and ozone (O3). The annual mean of CO for the entire period was 0.93 ± 0.22 ppm. CO levels were reduced by 83% from 3.25 ± 0.78 ppm (1987) to 0.51 ± 0.31 ppm (2013). Its relative reduction was compared over three periods chosen arbitrarily as period 1 (fast reduction, 1987–1988), period 2 (intermediate reduction, 1999–2000), and period 3 (slow reduction, 2004–2013). The concentrations of CO were strongly correlated with others (e.g., SO2, NO, NO2, O3, and Hg), suggesting the effects of similar source processes (e.g., fuel combustion). The reduction in its level was marginally consistent with the decreasing trend in the total CO column concentration in Seoul by the Measurements of Pollution in the Troposphere (MOPITT) satellite between 2000 and 2013, indicating decreasing anthropogenic CO emissions (despite increasing anthropogenic CO2 emissions). The rapid relative reduction of CO in period 1 and the subsequent slower but moderate reduction thereafter appear to reflect the effects of both enforcement of administrative regulations and advances in emissions control technologies.
Khan, A., J. E. Szulejko, M.-S. Bae, Z. H. Shon, J.-R. Sohn, J. W. Seo, E.-C. Jeon, and K.-H. Kim (2017b), Long-term trend analysis of CO in the Yongsan district of Seoul, Korea, between the years 1987 and 2013, Atmospheric Pollution Research, 8(5), 988–996, doi:10.1016/j.apr.2017.03.006.
In this study, the long-term trend in atmospheric carbon monoxide (CO) concentration was analyzed using the CO levels measured (intermittently) at an air quality monitoring (AQM) station in Seoul, Korea, between the years 1987 and 2013. Temporal trends in CO were analyzed on an annual and seasonal basis in reference to other important air pollutants such as methane (CH4), particulate matter (PM10), sulfur dioxide (SO2), nitrogen monoxide (NO), nitrogen dioxide (NO2), mercury (Hg), and ozone (O3). The annual mean of CO for the entire period was 0.93 ± 0.22 ppm. CO levels were reduced by 83% from 3.25 ± 0.78 ppm (1987) to 0.51 ± 0.31 ppm (2013). Its relative reduction was compared over three periods chosen arbitrarily as period 1 (fast reduction, 1987–1988), period 2 (intermediate reduction, 1999–2000), and period 3 (slow reduction, 2004–2013). The concentrations of CO were strongly correlated with others (e.g., SO2, NO, NO2, O3, and Hg), suggesting the effects of similar source processes (e.g., fuel combustion). The reduction in its level was marginally consistent with the decreasing trend in the total CO column concentration in Seoul by the Measurements of Pollution in the Troposphere (MOPITT) satellite between 2000 and 2013, indicating decreasing anthropogenic CO emissions (despite increasing anthropogenic CO2 emissions). The rapid relative reduction of CO in period 1 and the subsequent slower but moderate reduction thereafter appear to reflect the effects of both enforcement of administrative regulations and advances in emissions control technologies.
Kulawik, S. S., C. O’Dell, V. H. Payne, L. Kuai, H. M. Worden, S. C. Biraud, C. Sweeney, B. Stephens, L. T. Iraci, E. L. Yates, and T. Tanaka (2017), Lower-tropospheric CO2 from near-infrared ACOS-GOSAT observations, Atmos. Chem. Phys., 17(8), 5407–5438, doi:10.5194/acp-17-5407-2017.
We present two new products from near-infrared Greenhouse Gases Observing Satellite (GOSAT) observations: lowermost tropospheric (LMT, from 0 to 2.5 km) and upper tropospheric-stratospheric (U, above 2.5 km) carbon dioxide partial column mixing ratios. We compare these new products to aircraft profiles and remote surface flask measurements and find that the seasonal and year-to-year variations in the new partial column mixing ratios significantly improve upon the Atmospheric CO2 Observations from Space (ACOS) and GOSAT (ACOS-GOSAT) initial guess and/or a priori, with distinct patterns in the LMT and U seasonal cycles that match validation data. For land monthly averages, we find errors of 1.9, 0.7, and 0.8 ppm for retrieved GOSAT LMT, U, and X CO2; for ocean monthly averages, we find errors of 0.7, 0.5, and 0.5 ppm for retrieved GOSAT LMT, U, and X CO2. In the southern hemispheric biomass burning season, the new partial columns show similar patterns to MODIS fire maps and MOPITT multispectral CO for both vertical levels, despite a flat ACOS-GOSAT prior, and a CO-CO2 emission factor comparable to published values. The difference of LMT and U, useful for evaluation of model transport error, has also been validated with a monthly average error of 0.8 (1.4) ppm for ocean (land). LMT is more locally influenced than U, meaning that local fluxes can now be better separated from CO2 transported from far away.
Liu, J., K. W. Bowman, D. S. Schimel, N. C. Parazoo, Z. Jiang, M. Lee, A. A. Bloom, D. Wunch, C. Frankenberg, Y. Sun, C. W. O’Dell, K. R. Gurney, D. Menemenlis, M. Gierach, D. Crisp, and A. Eldering (2017), Contrasting carbon cycle responses of the tropical continents to the 2015–2016 El Niño, Science, 358(6360), eaam5690, doi:10.1126/science.aam5690.
Structured Abstract INTRODUCTIONThe influence of El Niño on climate is accompanied by large changes to the carbon cycle, and El Niño–induced variability in the carbon cycle has been attributed mainly to the tropical continents. However, owing to a dearth of observations in the tropics, tropical carbon fluxes are poorly quantified, and considerable debate exists over the dominant mechanisms (e.g., plant growth, respiration, fire) and regions (e.g., humid versus semiarid tropics) on the net carbon balance. RATIONALEThe launch of the Orbiting Carbon Observatory-2 (OCO-2) shortly before the 2015–2016 El Niño, the second strongest since the 1950s, has provided an opportunity to understand how tropical land carbon fluxes respond to the warm and dry climate characteristics of El Niño conditions. The El Niño events may also provide a natural experiment to study the response of tropical land carbon fluxes to future climate changes, because anomalously warm and dry tropical environments typical of El Niño are expected to be more frequent under most emission scenarios. RESULTSThe tropical regions of three continents (South America, Asia, and Africa) had heterogeneous responses to the 2015–2016 El Niño, in terms of both climate drivers and the carbon cycle. The annual mean precipitation over tropical South America and tropical Asia was lower by 3.0σ and 2.8σ, respectively, in 2015 relative to the 2011 La Niña year. Tropical Africa, on the other hand, had near equal precipitation and the same number of dry months between 2015 and 2011; however, surface temperatures were higher by 1.6σ, dominated by the positive anomaly over its eastern and southern regions. In response to the warmer and drier climate anomaly in 2015, the pantropical biosphere released 2.5 ± 0.34 gigatons more carbon into the atmosphere than in 2011, which accounts for 83.3% of the global total 3.0–gigatons of carbon (gigatons C) net biosphere flux differences and 92.6% of the atmospheric CO2 growth-rate differences between 2015 and 2011. It indicates that the tropical land biosphere flux anomaly was the driver of the highest atmospheric CO2 growth rate in 2015. The three tropical continents had an approximately even contribution to the pantropical net carbon flux anomaly in 2015, but had diverse dominant processes: gross primary production (GPP) reduced carbon uptake (0.9 ± 0.96 gigatons C) in tropical South America, fire increased carbon release (0.4 ± 0.08 gigatons C) in tropical Asia, and respiration increased carbon release (0.6 ± 1.01 gigatons C) in Africa. We found that most of the excess carbon release in 2015 was associated with either extremely low precipitation or high temperatures, or both. CONCLUSIONOur results indicate that the global El Niño effect is a superposition of regionally specific effects. The heterogeneous climate forcing and carbon response over the three tropical continents to the 2015–2016 El Niño challenges previous studies that suggested that a single dominant process determines carbon cycle interannual variability, which could also be due to previous disturbance and soil and vegetation structure. The similarity between the 2015 tropical climate anomaly and the projected climate changes imply that the role of the tropical land as a buffer for fossil fuel emissions may be reduced in the future. The heterogeneous response may reflect differences in temperature and rainfall anomalies, but intrinsic differences in vegetation species, soils, and prior disturbance may contribute as well. A synergistic use of multiple satellite observations and a long time series of spatially resolved fluxes derived from sustained satellite observations will enable tests of these hypotheses, allow for a more process-based understanding, and, ultimately, aid improved carbon-climate model projections. <img class="fragment-image" src="https://d2ufo47lrtsv5s.cloudfront.net/content/sci/358/6360/eaam5690/F1.medium.gif"/> Download high-res image Open in new tab Download Powerpoint Diverse climate driver anomalies and carbon cycle responses to the 2015–2016 El Niño over the three tropical continents.Schematic of climate anomaly patterns over the three tropical continents and the anomalies of the net carbon flux and its dominant constituent flux (i.e., GPP, respiration, and fire) relative to the 2011 La Niña during the 2015–2016 El Niño. GtC, gigatons C. The 2015–2016 El Niño led to historically high temperatures and low precipitation over the tropics, while the growth rate of atmospheric carbon dioxide (CO2) was the largest on record. Here we quantify the response of tropical net biosphere exchange, gross primary production, biomass burning, and respiration to these climate anomalies by assimilating column CO2, solar-induced chlorophyll fluorescence, and carbon monoxide observations from multiple satellites. Relative to the 2011 La Niña, the pantropical biosphere released 2.5 ± 0.34 gigatons more carbon into the atmosphere in 2015, consisting of approximately even contributions from three tropical continents but dominated by diverse carbon exchange processes. The heterogeneity of the carbon-exchange processes indicated here challenges previous studies that suggested that a single dominant process determines carbon cycle interannual variability.
Miyazaki, K., and K. Bowman (2017), Evaluation of ACCMIP ozone simulations and ozonesonde sampling biases using a satellite-based multi-constituent chemical reanalysis, Atmos. Chem. Phys., 17(13), 8285–8312, doi:10.5194/acp-17-8285-2017.
The Atmospheric Chemistry Climate Model Intercomparison Project (ACCMIP) ensemble ozone simulations for the present day from the 2000 decade simulation results are evaluated by a state-of-the-art multi-constituent atmospheric chemical reanalysis that ingests multiple satellite data including the Tropospheric Emission Spectrometer (TES), the Microwave Limb Sounder (MLS), the Ozone Monitoring Instrument (OMI), and the Measurement of Pollution in the Troposphere (MOPITT) for 2005–2009. Validation of the chemical reanalysis against global ozonesondes shows good agreement throughout the free troposphere and lower stratosphere for both seasonal and year-to-year variations, with an annual mean bias of less than 0.9 ppb in the middle and upper troposphere at the tropics and mid-latitudes. The reanalysis provides comprehensive spatiotemporal evaluation of chemistry-model performance that compliments direct ozonesonde comparisons, which are shown to suffer from significant sampling bias. The reanalysis reveals that the ACCMIP ensemble mean overestimates ozone in the northern extratropics by 6–11 ppb while underestimating by up to 18 ppb in the southern tropics over the Atlantic in the lower troposphere. Most models underestimate the spatial variability of the annual mean lower tropospheric concentrations in the extratropics of both hemispheres by up to 70 %. The ensemble mean also overestimates the seasonal amplitude by 25–70 % in the northern extratropics and overestimates the inter-hemispheric gradient by about 30 % in the lower and middle troposphere. A part of the discrepancies can be attributed to the 5-year reanalysis data for the decadal model simulations. However, these differences are less evident with the current sonde network. To estimate ozonesonde sampling biases, we computed model bias separately for global coverage and the ozonesonde network. The ozonesonde sampling bias in the evaluated model bias for the seasonal mean concentration relative to global coverage is 40–50 % over the western Pacific and east Indian Ocean and reaches 110 % over the equatorial Americas and up to 80 % for the global tropics. In contrast, the ozonesonde sampling bias is typically smaller than 30 % for the Arctic regions in the lower and middle troposphere. These systematic biases have implications for ozone radiative forcing and the response of chemistry to climate that can be further quantified as the satellite observational record extends to multiple decades.
Mok, J., S. S. Park, H. Lim, J. Kim, D. Edwards, J. Lee, J. Yoon, Y. G. Lee, and J.-H. Koo (2017a), Correlation analysis between regional carbon monoxide and black carbon from satellite measurements, Atmospheric Research, doi:10.1016/j.atmosres.2017.04.004. [online] Available from: http://www.sciencedirect.com/science/article/pii/S0169809516306445 .
In this study, we present and compare regional correlations between CO total column density (TCDCO) from the data set of Measurement of Pollution in the Troposphere (MOPITT), and high-absorbing BC dominant aerosol optical depth (AODBC) from the retrieval algorithm using Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI) (MODIS-OMI algorithm, MOA). TCDCO shows positive relationship to both fine-mode AOD (AODFM) and AODBC in general, but TCDCO better correlates with AODBC than AODFM. This enhanced correlation between TCDCO and AODBC appears more clearly during spring and summer. Correlation between TCDCO and AODBC is exceptionally poor in Northern Africa where the BC-dominated aerosols are frequently mixed with mineral dust particles from the Sahara. Another issue is also found in Southern Africa; the correlation between AODBC and TCDCO in this region is not much higher than that between the AODFM and TCDCO in spite of large occurrence of biomass burning and wildfire. This can be explained by the cloud perturbation near the source regions and dispersion effect due to the typical wind pattern. Correlations between AODBC and TCDCO increase further when fire detected areas are only considered, but does not change much over the urban area. This difference clarifies the large contribution of burning events to the positive relationship between BC and CO. All findings in this study demonstrate a possible use of satellite CO product in evaluating the BC-dominated aerosol product from satellite remote sensing over the globe.
Mok, J., S. S. Park, H. Lim, J. Kim, D. P. Edwards, J. Lee, J. Yoon, Y. G. Lee, and J.-H. Koo (2017b), Correlation analysis between regional carbon monoxide and black carbon from satellite measurements, Atmos. Res., 196, 29–39, doi:10.1016/j.atmosres.2017.04.004.
In this study, we present and compare regional correlations between CO total column density (TCDco) from the data set of Measurement of Pollution in the Troposphere (MOPITT), and high-absorbing BC dominant aerosol optical depth (AOD(Bc)) from the retrieval algorithm using Moderate Resolution Imaging Spectroradiometer (MODIS) and Ozone Monitoring Instrument (OMI) (MODIS-OMI algorithm, MOA). TCDco shows positive relationship to both fine -mode AOD (AOD(Fm)) and AODBc in general, but TCDco better correlates with AODBc than AODFm. This enhanced correlation between TCDco and AODBc appears more clearly during spring and summer. Correlation between TCDco and AODBc is exceptionally poor in Northern Africa where the BC dominated aerosols are frequently mixed with mineral dust particles from the Sahara. Another issue is also found in Southern Africa; the correlation between AODBc and TCDco in this region is not much higher than that between the AODFm and TCDco in spite of large occurrence of biomass burning and wildfire. This can be explained by the cloud perturbation near the source regions and dispersion effect due to the typical wind pattern. Correlations between AODBc and TCDco increase further when fire detected areas are only considered, but does not change much over the urban area. This difference clarifies the large contribution of burning events to the positive relationship between BC and CO. All findings in this study demonstrate a possible use of satellite CO product in evaluating the BC-dominated aerosol product from satellite remote sensing over the globe.
Pandey, A. K., A. K. Mishra, R. Kumar, S. Berwal, R. Devadas, A. Huete, and K. Kumar (2017), CO variability and its association with household cooking fuels consumption over the Indo-Gangetic Plains, Environmental Pollution, 222, 83–93, doi:10.1016/j.envpol.2016.12.080.
This study examines the spatio-temporal trends obtained from decade long (Jan 2003–Dec 2014) satellite observational data of Atmospheric Infrared Sounder (AIRS) and Measurements of Pollution in the Troposphere (MOPITT) on carbon monoxide (CO) concentration over the Indo-Gangetic Plains (IGP) region. The time sequence plots of columnar CO levels over the western, central and eastern IGP regions reveal marked seasonal behaviour, with lowest CO levels occurring during the monsoon months and the highest CO levels occurring during the pre-monsoon period. A negative correlation between CO levels and rainfall is observed. CO vertical profiles show relatively high values in the upper troposphere at ∼200 hPa level during the monsoon months, thus suggesting the role of convective transport and advection in addition to washout behind the decreased CO levels during this period. MOPITT and AIRS observations show a decreasing trend of 9.6 × 1015 and 1.5 × 1016 molecules cm−2 yr−1, respectively, in columnar CO levels over the IGP region. The results show the existence of a spatial gradient in CO from the eastern (higher levels) to western IGP region (lower levels). Data from the Census of India on the number of households using various cooking fuels in the IGP region shows the prevalence of biomass-fuel (i.e. firewood, crop residue, cowdung etc.) use over the eastern and central IGP regions and that of liquefied petroleum gas over the western IGP region. CO emission estimates from cooking activity over the three IGP regions are found to be in the order east &gt; central &gt; west, which support the existence of the spatial gradient in CO from eastern to the western IGP region. Our results support the intervention of present Indian government on limiting the use of biomass-fuels in domestic cooking to achieve the benefits in terms of the better air quality, household health and regional/global climate change mitigation.
Sitnov, S. A., I. I. Mokhov, and A. V. Dzhola (2017), Total content of carbon monoxide in the atmosphere over Russian regions according to satellite data, Izvestiya, Atmospheric and Oceanic Physics, 1(53), 32–48, doi:10.1134/S0001433817010121.
Carbon monoxide (CO) total columns over European Russia (ER) and western Siberia (WS) have been analyzed using MOPITT (V5, TIR/NIR, L3) IR-radiometer data obtained in 2000–2014. High CO contents are revealed over large urban and industrial agglomerations and over regions of oil-and-gas production. A stable local CO maximum is observed over the Moscow agglomeration. Statistical characteristics of CO total columns observed in the atmosphere over ER and WS in 2000–2014 are presented. An analysis of long-term changes in CO content reveals nonlinear changes in the CO total column over northern Eurasia in 2000–2014. Results of a comparative analysis of annual variations in atmospheric CO contents over ER and WS are given. Based on Fourier analysis, empirical models of annual variations in total CO contents over ER and WS are proposed. Relations between regional CO contents and fire characteristics and between spatial CO distributions and features of large-scale atmospheric dynamics under conditions of weather and climate anomalies in the summers of 2010 in ER and 2012 in WS are analyzed. Data on total CO contents measured with a MOPITT satellite radiometer and a ground-based spectrometer operating at the Zvenigorod Scientific Station of the Obukhov Institute of Atmospheric Physics are compared.
SUN YuTao, GUO ZhengFu, CHENG ZhiHui, ZHANG MaoLiang, and ZHANG LiHong (2017), Gaseous anomalies related to the activities of Changbai Volcano in 2002 ~ 2005 : Evidence from multi-sensor hyperspatial satellite archived data, Acta Petrologica Sinica, 33(1). [online] Available from: http://d.wanfangdata.com.cn/periodical/ysxb98201701018.
长白山火山区是我国具有潜在喷发危险的活火山,在2002~2005年火山活动性增强出现了岩浆房扰动.利用卫星遥感技术具有观测范围大、观测时间长且连续的优势.因此,本文利用对流层污染探测仪(MOPITT)和大气红外探测仪(AIRS)高光谱遥感数据提取了2002~2005年长白山天池火山区CO总量、O3总量、水汽总量和地表温度异常信息,讨论了高光谱遥感气体地球化学异常信息与火山活动性之间的关系,并对2002~2005年长白山天池火山区火山活动性进行了研究.结果表明,高光谱遥感数据观测到的气体地球化学(CO、O3、水汽)异常与地震、形变监测结果以及地面流体(CO2、He、H2)观测结果相一致,表明MOPITT和AIRS高光谱遥感卫星观测到的气体异常变化较好地反映了2002~ 2005年大规模的深部岩浆局部扰动.在2002~2005年火山活动期间,CO总量、O3总量、水汽总量和地表温度均出现了显著异常且异常出现时段相应准偏差显著增大,反映了气体选出量在时间上具有不均一性,可能与火山、地震活动过程中地应力的作用和变化有关.从气体异常持续的时间以及地面观测结果综合分析,2002~2005年岩浆房扰动并没有产生长时间的地幔物质流的上升和迁移.在火山活动性增强的时间段内,地表温度出现异常低值,这可能与太平洋板块俯冲过程中引起的断裂拉张增强有关.此外,火山活动过程中选出的气体进入大气圈产生大气化学反应也会导致高光谱遥感所观测到的气体地球化学异常.研究结果为2002~2005年长白山火山活动性的研究提供了来自高光谱遥感数据的气体地球化学新证据,也对高光谱分辨率遥感数据在火山活动规律的研究以及火山监测中的应用具有一定意义.
Tratt, D. M., S. J. Young, J. A. Hackwell, D. J. Rudy, D. W. Warren, A. G. Vore, and P. D. Johnson (2017), MAHI: An Airborne Mid-Infrared Imaging Spectrometer for Industrial Emissions Monitoring, IEEE Transactions on Geoscience and Remote Sensing, 55(8), 4558–4566, doi:10.1109/TGRS.2017.2693979.
An airborne hyperspectral imager operating in the midwave-infrared spectral range is described. The Mid-infrared Airborne Hyperspectral Imager (MAHI) features 3.3-nm spectral sampling over its 3.3-5.4 μm wavelength range. MAHI operates in a roll-stabilized pushbroom configuration with 480 crosstrack pixels, each with an instantaneous field-of-view (IFOV) of 0.94 mrad, to provide for a total FOV of 25.8°. The sensor spectroradiometric performance is illustrated by case studies featuring the detection, identification, and quantification of a number of fugitive gaseous emissions from industrial sources.
Verma, N., A. Satsangi, A. Lakhani, K. M. Kumari, and S. Lal (2017), Diurnal, Seasonal, and Vertical Variability in Carbon Monoxide Levels at a Semi-Urban Site in India, Clean Soil Air Water, n/a-n/a, doi:10.1002/clen.201600432.
In the present study, near-surface carbon monoxide (CO) measurements were carried out at a semi-urban site in Agra, India (27°10′N, 78°05′E), during March 2015 to February 2016. The study includes the diurnal, seasonal, and vertical variation of CO and the effect of meteorological parameters on its levels. The diurnal variation of CO was characterized by high levels during morning (9–10 am) and evening (10–11 pm) hours and low levels during the afternoon (3–5 pm). The morning and evening peak levels may be due to high emissions from traffic and low planetary boundary layer (PBL) height which prevents dispersion of pollutants. The low levels during afternoon hours may be due to increasing PBL height and loss through photochemical reactions. CO showed a distinct seasonal variation with highest levels in winter (770 ± 466 ppb) and lowest in monsoon (153 ± 122 ppb). The high levels in the winter season may be attributed to increased emissions from coal and wood burning used for heating in combination with stagnant weather conditions. The study also included latest retrievals of CO using Measurements of Pollution in the Troposphere (MOPITT) to define the vertical and seasonal variation of CO. The pattern of seasonal variation observed by ground level measurements was consistent with MOPITT surface CO levels.
Worden, J. R., A. A. Bloom, S. Pandey, Z. Jiang, H. M. Worden, T. W. Walker, S. Houweling, and T. Rockmann (2017), Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget, Nat. Commun., 8, 2227, doi:10.1038/s41467-017-02246-0.
Several viable but conflicting explanations have been proposed to explain the recent similar to 8 p.p.b. per year increase in atmospheric methane after 2006, equivalent to net emissions increase of similar to 25 Tg CH4 per year. A concurrent increase in atmospheric ethane implicates a fossil source; a concurrent decrease in the heavy isotope content of methane points toward a biogenic source, while other studies propose a decrease in the chemical sink (OH). Here we show that biomass burning emissions of methane decreased by 3.7 (+/- 1.4) Tg CH4 per year from the 2001-2007 to the 2008-2014 time periods using satellite measurements of CO and CH4, nearly twice the decrease expected from prior estimates. After updating both the total and isotopic budgets for atmospheric methane with these revised biomass burning emissions (and assuming no change to the chemical sink), we find that fossil fuels contribute between 12-19 Tg CH4 per year to the recent atmospheric methane increase, thus reconciling the isotopic-and ethane-based results.
Yarragunta, Y., S. Srivastava, and D. Mitra (2017), Validation of lower tropospheric carbon monoxide inferred from MOZART model simulation over India, Atmospheric Research, 184, 35–47, doi:10.1016/j.atmosres.2016.09.010.
In the present study, MOZART-4 (Model for Ozone and Related chemical Tracers-Version-4) simulation has been made from 2003 to 2007 and compared with satellite and in-situ observations with a specific focus on Indian subcontinent to illustrate the capabilities of MOZART-4 model. The model simulated CO have been compared with latest version (version-6) of MOPITT (Measurement Of Pollution In The Troposphere) carbon monoxide (CO) retrievals at 900, 800 and 700 hPa. Model reproduces major features present in satellite observations. However model significantly overestimates CO over the entire Indian region at 900 hPa and moderately overestimates at 800 hPa and 700 hPa. The frequency distribution of all simulated data points with respect to MOZART error shows maximum in the error range of 10–20% at all pressure levels. Over total Indian landmass, the percentage of gridded CO data that are being overestimated in the range of 0–30% at 900 hPa, 800 hPa and 700 hPa are 58%, 62% and 66% respectively. The study reflects very good correlation between two datasets over Central India (CI) and Southern India (SI). The coefficient of determination (r2) is found to be 0.68–0.78 and 0.70–0.78 over the CI and SI respectively. The weak correlation is evident over Northern India (NI) with r2 values of 0.1–0.3. Over Eastern India (EI), Good correlation at 800 hPa (r2 = 0.72) and 700 hPa (r2 = 0.66) whereas moderately weak correlation at 900 hPa (r2 = 0.48) has been observed. In contrast, Over Western India (WI), strong correlation is evident at 900 hPa (r2 = 0.64) and moderately weak association is found to be present at 800 hPa and 700 hPa. Model fairly reproduces seasonal cycle of CO in the lower troposphere over most of the Indian regions. However, during June to December, model shows overestimation over NI. The magnitude of overestimation is increasing linearly from 900 hPa to 700 hPa level. During April–June months, model results are coinciding with observed CO concentrations over SI region at 900 hPa. Model simulation has been compared with surface in-situ observations over ten Indian locations. Model performance is found to be moderate to good over various observational locations. However, over highly polluted megacities, model underestimates observed CO concentration by up to 3500 ppbv. A case study over the forest fire prone area reveals the clear increase of modeled and retrieved CO in February–March and a decrease in May which is coinciding with biomass burning emissions and fire counts. Model performance is found to be relatively poor over this region with r2 of 0.29 and slope of 0.56.
Zhang, X., D. B. A. Jones, M. Keller, Z. Jiang, A. E. Bourassa, D. A. Degenstein, C. Clerbaux, and P.-F. Coheur (2017), Global CO emission estimates inferred from assimilation of MOPITT and IASI CO data, together with observations of O3, NO2, HNO3, and HCHO. [online] Available from: https://hal-insu.archives-ouvertes.fr/insu-01675772 .
Atmospheric carbon monoxide (CO) emissions estimated from inverse modeling analyses exhibit large uncertainties, due, in part, to discrepancies in the tropospheric chemistry in atmospheric models. We attempt to reduce the uncertainties in CO emission estimates by constraining the modeled abundance of ozone (O3), nitrogen dioxide (NO2), nitric acid (HNO3), and formaldehyde (HCHO), which are constituents that play a key role in tropospheric chemistry. Using the GEOS-Chem four-dimensional variational (4D-Var) data assimilation system, we estimate CO emissions by assimilating observations of CO from the Measurement of Pollution In the Troposphere (MOPITT) and the Infrared Atmospheric Sounding Interferometer (IASI), together with observations of O3 from the Optical Spectrograph and InfraRed Imager System (OSIRIS) and IASI, NO2 and HCHO from the Ozone Monitoring Instrument (OMI), and HNO3 from the Microwave Limb Sounder (MLS). Our experiments evaluate the inferred CO emission estimates from major anthropogenic, biomass burning and biogenic sources. Moreover, we also infer surface emissions of nitrogen oxides (NOx = NO + NO2) and isoprene. Our results reveal that this multiple species chemical data assimilation produces a chemical consistent state that effectively adjusts the CO-O3-OH coupling in the model. The O3-induced changes in OH are particularly large in the tropics. Overall, our analysis results in a better constrained tropospheric chemical state.
Zhou, Y., H. Mao, K. Demerjian, C. Hogrefe, and J. Liu (2017), Regional and hemispheric influences on temporal variability in baseline carbon monoxide and ozone over the Northeast US, Atmospheric Environment, 164, 309–324, doi:10.1016/j.atmosenv.2017.06.017.
Interannual variability in baseline carbon monoxide (CO) and ozone (O3), defined as mixing ratios under minimal influence of recent and local emissions, was studied for seven rural sites in the Northeast US over 2001–2010. Annual baseline CO exhibited statistically significant decreasing trends (−4.3 to −2.3 ppbv yr−1), while baseline O3 did not display trends at any site. In examining the data by season, wintertime and springtime baseline CO at the two highest sites (1.5 km and 2 km asl) did not experience significant trends. Decadal increasing trends (∼2.55 ppbv yr−1) were found in springtime and wintertime baseline O3 in southern New Hampshire, which was associated with anthropogenic NOx emission reductions from the urban corridor. Biomass burning emissions impacted summertime baseline CO with ∼38% variability from wildfire emissions in Russia and ∼22% from Canada at five sites and impacted baseline O3 at the two high elevation sites only with ∼27% variability from wildfires in both Russia and Canada. The Arctic Oscillation was negatively correlated with summertime baseline O3, while the North Atlantic Oscillation was positively correlated with springtime baseline O3. This study suggested that anthropogenic and biomass burning emissions, and meteorological conditions were important factors working together to determine baseline O3 and CO in the Northeast U.S. during the 2000s.
Ситнов, С. А., И. И. Мохов, and А. В. Джола (2017), Общее содержание оксида углерода в атмосфере над российскими регионами по спутниковым данным, Известия Российской Академии Наук. Физика Атмосферы И Океана, 53(1), 38–55.
Carbon monoxide (CO) total columns over European Russia (ER) and western Siberia (WS) have been analyzed using MOPITT (V5, TIR/NIR, L3) IR-radiometer data obtained in 2000–2014. High CO contents are revealed over large urban and industrial agglomerations and over regions of oil-and-gas production. A stable local CO maximum is observed over the Moscow agglomeration. Statistical characteristics of CO total columns observed in the atmosphere over ER and WS in 2000–2014 are presented. An analysis of long-term changes in CO content reveals nonlinear changes in the CO total column over northern Eurasia in 2000–2014. Results of a comparative analysis of annual variations in atmospheric CO contents over ER and WS are given. Based on Fourier analysis, empirical models of annual variations in total CO contents over ER and WS are proposed. Relations between regional CO contents and fire characteristics and between spatial CO distributions and features of large-scale atmospheric dynamics under conditions of weather and climate anomalies in the summers of 2010 in ER and 2012 in WS are analyzed. Data on total CO contents measured with a MOPITT satellite radiometer and a ground-based spectrometer operating at the Zvenigorod Scientific Station of the Obukhov Institute of Atmospheric Physics are compared. Keywords: Carbon monoxide, MOPITT, annual cycle, trend, wildfires, comparison between satellite and ground-based data

2016

Azmi, U., and M. Marzuki (2016), Distribusi Vertikal Karbon Monoksida di Sumatera Berdasarkan Pengamatan Measurement of Pollution in the Troposphere (MOPITT) Selama Kebakaran Hutan Tahun 2015, Jurnal Fisika Unand, 5(3), 252–260.
Distribusi vertikal karbon monoksida (CO) di Sumatera selama kebakaran hutan tahun 2015 telah diteliti menggunakan data satelit MOPITT (Measurements of Pollution in the Troposphere). Pengaruh proses konveksi terhadap pergerakan CO ke lapisan atmosfer diamati dengan data OLR (Outgoing Longwave Radiation) dan pergerakan udara dari data NCEP/NCAR (National Centers for Environmental Prediction/National Center for Atmospheric Research). Hasil penelitian memperlihatkan bahwa kebakaran hutan tahun 2015 telah meningkatkan konsentrasi CO di Indonesia. Namun, jumlah gas CO yang terekam oleh MOPITT tidak terlalu tinggi (~40-120 ppbv). Hal ini disebabkan oleh tingginya konsentrasi uap air di ekuator sehingga konsentrasi CO rendah dan waktu tinggal CO di atmosfer juga berkurang. Selain di permukaan, peningkatan konsentrasi CO juga teramati pada lapisan atmosfer yang lebih tinggi. Namun, hubungan antara pergerakan CO ke lapisan atmosfer atas dengan aktivitas konveksi sulit untuk diamati dengan data satelit MOPITT. Perulangan waktu pengamatan MOPITT untuk titik pengamatan yang sama cukup lama yaitu 4 hari menjadi salah satu kendala. Walaupun demikian, dari tiga studi kasus yang diteliti, teramati pengaruh konveksi terhadap pergerakan CO ke atas pada dua kasus yaitu tanggal 11 dan 15 Oktober 2015. Pada 11 Oktober, jumlah CO bertambah dari 60 ppbv menuju 80-100 ppbv dan pada tanggal 15 Oktober, juga mengalami peningkatan dari 60 ppbv menjadi 80-90 ppbv pada 100 hPa.Kata kunci:CO, MOPITT, konveksi, Sumatera, kebakaran hutan 2015
Borsdorff, T., P. Tol, J. E. Williams, J. de Laat, J. aan de Brugh, P. Nedelec, I. Aben, and J. Landgraf (2016), Carbon monoxide total columns from SCIAMACHY 2.3 mu m atmospheric reflectance measurements: towards a full-mission data product (2003-2012), Atmos. Meas. Tech., 9(1), 227–248, doi:10.5194/amt-9-227-2016.
We present a full-mission data product of carbon monoxide ( CO) vertical column densities using the 2310-2338 nm SCIAMACHY reflectance measurements over clear-sky land scenes for the period January 2003-April 2012. The retrieval employs the SICOR algorithm, which will be used for operational data processing of the Sentinel-5 Precursor mission. The retrieval approach infers simultaneously carbon monoxide, methane and water vapour column densities together with a Lambertian surface albedo from individual SCIAMACHY measurements employing a non-scattering radiative transfer model. To account for the radiometric instrument degradation including the formation of an ice-layer on the 2.3 mu m detector array, we consider clear-sky measurements over the Sahara as a natural calibration target. For these specific measurements, we spectrally calibrate the SCIAMACHY measurements and determine a spectral radiometric offset and the width of the instrument spectral response function as a function of time for the entire operational phase of the mission. We show that the smoothing error of individual clear-sky CO retrievals is less than +/- 1 ppb and thus this error contribution does not need to be accounted for in the validation considering the much higher retrieval noise. The CO data product is validated against measurements of ground-based Fourier transform infrared spectrometers at 27 stations of the NDACC-IRWG and TCCON network and MOZAIC/IAGOS aircraft measurements at 26 airports worldwide. Overall, we find a good agreement with TCCON measurements with a mean bias N (b) over bar = -1.2 ppb and a station-to-station bias with (sigma) over bar = 7.2 ppb. The negative sign of the bias means a low bias of SCIAMACHY CO with respect to TCCON. For the NDACC-IRWG network, we obtain a larger mean station bias of N (b) over bar = -92 ppb with (sigma) over bar = 8.1 ppb and for the MOZAIC/IAGOS measurements we find (b) over bar = -6.4 ppb with (sigma) over bar = 5.6 ppb. The SCIAMACHY data set is subject to a small but significant bias trend of 1.47 +/- 0.25 ppbyr(-1). After trend correction, the bias with respect to MOZAIC/IAGOS observation is 2.5 ppb, with respect to TCCON measurements it is -4.6 ppb and with respect to NDACC-IRWG measurements -8.4 ppb. Hence, a discrepancy of 3.8 ppb remains between the global biases with NDACC-IRWG and TCCON, which is confirmed by directly comparing NDACC-IRWG and TCCON measurements. Generally, the scatter of the individual SCIAMACHY CO retrievals is high and dominated by large measurement noise. Hence, for practical usage of the data set, averaging of individual retrievals is required. As an example, we show that monthly mean SCIAMACHY CO retrievals, averaged separately over Northern and Southern Africa, reflect the spatial and temporal variability of biomass burning events in agreement with the global chemical transport model TM5.
Cai, C., X. Zhang, K. Wang, Y. Zhang, L. Wang, Q. Zhang, F. Duan, K. He, and S.-C. Yu (2016), Incorporation of new particle formation and early growth treatments into WRF/Chem: Model improvement, evaluation, and impacts of anthropogenic aerosols over East Asia, Atmospheric Environment, 124, Part B, 262–284, doi:10.1016/j.atmosenv.2015.05.046.
New particle formation (NPF) provides an important source of aerosol particles and cloud condensation nuclei, which may result in enhanced cloud droplet number concentration (CDNC) and cloud shortwave albedo. In this work, several nucleation parameterizations and one particle early growth parameterization are implemented into the online-coupled Weather Research and Forecasting model coupled with chemistry (WRF/Chem) to improve the model’s capability in simulating NPF and early growth of ultrafine particles over East Asia. The default 8-bin over the size range of 39 nm–10 μm used in the Model for Simulating Aerosol Interactions and Chemistry aerosol module is expanded to the 12-bin over 1 nm–10 μm to explicitly track the formation and evolution of new particles. Although model biases remain in simulating H2SO4, condensation sink, growth rate, and formation rate, the evaluation of July 2008 simulation identifies a combination of three nucleation parameterizations (i.e., COMB) that can best represent the atmospheric nucleation processes in terms of both surface nucleation events and the resulting vertical distribution of ultrafine particle concentrations. COMB consists of a power law of Wang et al. (2011) based on activation theory for urban areas in planetary boundary layer (PBL), a power law of Boy et al. (2008) based on activation theory for non-urban areas in PBL, and the ion-mediated nucleation parameterization of YU10 for above PBL. The application and evaluation of the improved model with 12-bin and the COMB nucleation parameterization in East Asia during January, April, July, and October in 2001 show that the model has an overall reasonably good skill in reproducing most observed meteorological variables and surface and column chemical concentrations. Relatively large biases in simulated precipitation and wind speeds are due to inaccurate surface roughness and limitations in model treatments of cloud formation and aerosol-cloud-precipitation interactions. Large biases in the simulated surface concentrations of PM10, NOx, CO, SO2, and VOCs at some sites are due in part to possible underestimations of emissions and in part to inaccurate meteorological predictions. The simulations of 2001 show that anthropogenic aerosols can increase aerosol optical depth by 64.0–228.3%, CDNC by 40.2–76.4%, and cloud optical thickness by 14.3–25.3%; they can reduce surface net shortwave radiation by up to 42.5–52.8 W m−2, 2-m temperature by up to 0.34–0.83 °C, and PBL height by up to 76.8–125.9 m. Such effects are more significant than those previously reported for the U.S. and Europe.
Deeter, M. N., S. Martínez-Alonso, L. V. Gatti, M. Gloor, J. B. Miller, L. G. Domingues, and C. S. C. Correia (2016), Validation and analysis of MOPITT CO observations of the Amazon Basin, Atmos. Meas. Tech., 9(8), 3999–4012, doi:10.5194/amt-9-3999-2016.
We analyze satellite retrievals of carbon monoxide from the MOPITT (Measurements of Pollution in the Troposphere) instrument over the Amazon Basin, focusing on the MOPITT Version 6 “multispectral” retrieval product (exploiting both thermal-infrared and near-infrared channels). Validation results based on in situ vertical profiles measured between 2010 and 2013 are presented for four sites in the Amazon Basin. Results indicate a significant negative bias in retrieved lower-tropospheric CO concentrations. The possible influence of smoke aerosol as a source of retrieval bias is investigated using collocated Aerosol Robotic Network (AERONET) aerosol optical depth (AOD) measurements at two sites but does not appear to be significant. Finally, we exploit the MOPITT record to analyze both the mean annual cycle and the interannual variability of CO over the Amazon Basin since 2002.
Field, R. D., G. R. van der Werf, T. Fanin, E. J. Fetzer, R. Fuller, H. Jethva, R. Levy, N. J. Livesey, M. Luo, O. Torres, and H. M. Worden (2016), Indonesian fire activity and smoke pollution in 2015 show persistent nonlinear sensitivity to El Nino-induced drought, Proc. Natl. Acad. Sci. U. S. A., 113(33), 9204–9209, doi:10.1073/pnas.1524888113.
The 2015 fire season and related smoke pollution in Indonesia was more severe than the major 2006 episode, making it the most severe season observed by the NASA Earth Observing System satellites that go back to the early 2000s, namely active fire detections from the Terra and Aqua Moderate Resolution Imaging Spectroradiometers (MODIS), MODIS aerosol optical depth, Terra Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO), Aqua Atmospheric Infrared Sounder (AIRS) CO, Aura Ozone Monitoring Instrument (OMI) aerosol index, and Aura Microwave Limb Sounder (MLS) CO. The MLS CO in the upper troposphere showed a plume of pollution stretching from East Africa to the western Pacific Ocean that persisted for 2 mo. Longer-term records of airport visibility in Sumatra and Kalimantan show that 2015 ranked after 1997 and alongside 1991 and 1994 as among the worst episodes on record. Analysis of yearly dry season rainfall from the Tropical Rainfall Measurement Mission (TRMM) and rain gauges shows that, due to the continued use of fire to clear and prepare land on degraded peat, the Indonesian fire environment continues to have nonlinear sensitivity to dry conditions during prolonged periods with less than 4 mm/d of precipitation, and this sensitivity appears to have increased over Kalimantan. Without significant reforms in land use and the adoption of early warning triggers tied to precipitation forecasts, these intense fire episodes will reoccur during future droughts, usually associated with El Nino events.
Fu, D., K. W. Bowman, H. M. Worden, V. Natraj, J. R. Worden, S. Yu, P. Veefkind, I. Aben, J. Landgraf, L. Strow, and Y. Han (2016), High-resolution tropospheric carbon monoxide profiles retrieved from CrIS and TROPOMI, Atmos. Meas. Tech., 9(6), 2567–2579, doi:10.5194/amt-9-2567-2016.
The Measurements of Pollution in the Troposphere (MOPITT) instrument is the only satellite-borne sensor in operation that uses both thermal (TIR) and near-infrared (NIR) channels to estimate CO profiles. With more than 15 years (2000 to present) of validated multispectral observations, MOPITT provides the unique capability to separate CO in the lowermost troposphere (LMT, surface to 3 km (similar to 700 hPa)) from the free-tropospheric abundance. To extend this record, a new, hyper-spectral approach is presented here that will provide CO data products exceeding the capabilities of MOPITT by combining the short-wavelength infrared (SWIR, equivalent to the MOPITT NIR) channels from the TROPOspheric Monitoring Instrument (TROPOMI) to be launched aboard the European Sentinel 5 Precursor (S5p) satellite in 2016 and the TIR channels from the Cross-track Infrared Sounder (CrIS) aboard the Suomi National Polar-orbiting Partnership (Suomi NPP) satellite. We apply the MUlti-SpEctra, MUlti-SpEcies, Multi-SEnsors (MUSES) retrieval algorithm to quantify the potential of this joint CO product. CO profiles are retrieved from a single-footprint, full-spectral-resolution CrIS transect over Africa on 27-28 August 2013 coincident with significant biomass burning. Comparisons of collocated CrIS and MOPITT CO observations for the LMT show a mean difference of 2.8 +/- 24.9 ppb, which is well within the estimated measurement uncertainty of both sensors. The estimated degrees of freedom (DOF) for CO signals from synergistic CrIS-TROPOMI retrievals are approximately 0.9 in the LMT and 1.3 above the LMT, which indicates that the LMT CO can be distinguished from the free troposphere, similar to MOPITT multispectral observations (0.8 in the LMT, and 1.1 above the LMT). In addition to increased sensitivity, the combined retrievals reduce measurement uncertainty, with similar to 15% error reduction in the LMT. With a daily global coverage and a combined spatial footprint of 14 km, the joint CrIS-TROPOMI measurements have the potential to extend and improve upon the MOPITT multispectral CO data records for the coming decade.
Gaubert, B., A. F. Arellano, J. Barré, H. M. Worden, L. K. Emmons, S. Tilmes, R. R. Buchholz, F. Vitt, K. Raeder, N. Collins, J. L. Anderson, C. Wiedinmyer, S. Martinez Alonso, D. P. Edwards, M. O. Andreae, J. W. Hannigan, C. Petri, K. Strong, and N. Jones (2016), Toward a chemical reanalysis in a coupled chemistry-climate model: An evaluation of MOPITT CO assimilation and its impact on tropospheric composition, J. Geophys. Res. Atmos., 121(12), 2016JD024863, doi:10.1002/2016JD024863.
We examine in detail a 1 year global reanalysis of carbon monoxide (CO) that is based on joint assimilation of conventional meteorological observations and Measurement of Pollution in The Troposphere (MOPITT) multispectral CO retrievals in the Community Earth System Model (CESM). Our focus is to assess the impact to the chemical system when CO distribution is constrained in a coupled full chemistry-climate model like CESM. To do this, we first evaluate the joint reanalysis (MOPITT Reanalysis) against four sets of independent observations and compare its performance against a reanalysis with no MOPITT assimilation (Control Run). We then investigate the CO burden and chemical response with the aid of tagged sectoral CO tracers. We estimate the total tropospheric CO burden in 2002 (from ensemble mean and spread) to be 371 ± 12% Tg for MOPITT Reanalysis and 291 ± 9% Tg for Control Run. Our multispecies analysis of this difference suggests that (a) direct emissions of CO and hydrocarbons are too low in the inventory used in this study and (b) chemical oxidation, transport, and deposition processes are not accurately and consistently represented in the model. Increases in CO led to net reduction of OH and subsequent longer lifetime of CH4 (Control Run: 8.7 years versus MOPITT Reanalysis: 9.3 years). Yet at the same time, this increase led to 5–10% enhancement of Northern Hemisphere O3 and overall photochemical activity via HOx recycling. Such nonlinear effects further complicate the attribution to uncertainties in direct emissions alone. This has implications to chemistry-climate modeling and inversion studies of longer-lived species.
Glotfelty, T., Y. Zhang, P. Karamchandani, and D. G. Streets (2016), Changes in future air quality, deposition, and aerosol-cloud interactions under future climate and emission scenarios, Atmospheric Environment, 139, 176–191, doi:10.1016/j.atmosenv.2016.05.008.
The prospect of global climate change will have wide scale impacts, such as ecological stress and human health hazards. One aspect of concern is future changes in air quality that will result from changes in both meteorological forcing and air pollutant emissions. In this study, the GU-WRF/Chem model is employed to simulate the impact of changing climate and emissions following the IPCC AR4 SRES A1B scenario. An average of 4 future years (2020, 2030, 2040, and 2050) is compared against an average of 2 current years (2001 and 2010). Under this scenario, by the Mid-21st century global air quality is projected to degrade with a global average increase of 2.5 ppb in the maximum 8-hr O3 level and of 0.3 μg m−3 in 24-hr average PM2.5. However, PM2.5 changes are more regional due to regional variations in primary aerosol emissions and emissions of gaseous precursor for secondary PM2.5. Increasing NOx emissions in this scenario combines with a wetter climate elevating levels of OH, HO2, H2O2, and the nitrate radical and increasing the atmosphere’s near surface oxidation state. This differs from findings under the RCP scenarios that experience declines in OH from reduced NOx emissions, stratospheric recovery of O3, and increases in CH4 and VOCs. Increasing NOx and O3 levels enhances the nitrogen and O3 deposition, indicating potentially enhanced crop damage and ecosystem stress under this scenario. The enhanced global aerosol level results in enhancements in aerosol optical depth, cloud droplet number concentration, and cloud optical thickness. This leads to dimming at the Earth’s surface with a global average reduction in shortwave radiation of 1.2 W m−2. This enhanced dimming leads to a more moderate warming trend and different trends in radiation than those found in NCAR’s CCSM simulation, which does not include the advanced chemistry and aerosol treatment of GU-WRF/Chem and cannot simulate the impacts of changing climate and emissions with the same level of detailed treatments. This study indicates that effective climate mitigation and emission control strategies are needed to prevent future health impact and ecosystem stress. Further, studies that are used to develop these strategies should use fully coupled models with sophisticated chemical and aerosol-interaction treatments that can provide a more realistic representation of the atmosphere.
Hoshyaripour, G., G. Brasseur, M. F. Andrade, M. Gavidia-Calderón, I. Bouarar, and R. Y. Ynoue (2016), Prediction of ground-level ozone concentration in São Paulo, Brazil: Deterministic versus statistic models, Atmospheric Environment, 145, 365–375, doi:10.1016/j.atmosenv.2016.09.061.
Two state-of-the-art models (deterministic: Weather Research and Forecast model with Chemistry (WRF-Chem) and statistic: Artificial Neural Networks: (ANN)) are implemented to predict the ground-level ozone concentration in São Paulo (SP), Brazil. Two domains are set up for WRF-Chem simulations: a coarse domain (with 50 km horizontal resolution) including whole South America (D1) and a nested domain (with horizontal resolution of 10 km) including South Eastern Brazil (D2). To evaluate the spatial distribution of the chemical species, model results are compared to the Measurements of Pollution in The Troposphere (MOPITT) data, showing that the model satisfactorily predicts the CO concentrations in both D1 and D2. The model also reproduces the measurements made at three air quality monitoring stations in SP with the correlation coefficients of 0.74, 0.70, and 0.77 for O3 and 0.51, 0.48, and 0.57 for NOx. The input selection for ANN model is carried out using Forward Selection (FS) method. FS-ANN is then trained and validated using the data from two air quality monitoring stations, showing correlation coefficients of 0.84 and 0.75 for daily mean and 0.64 and 0.67 for daily peak ozone during the test stage. Then, both WRF-Chem and FS-ANN are deployed to forecast the daily mean and peak concentrations of ozone in two stations during 5–20 August 2012. Results show that WRF-Chem preforms better in predicting mean and peak ozone concentrations as well as in conducting mechanistic and sensitivity analysis. FS-ANN is only advantageous in predicting mean daily ozone concentrations considering its significantly lower computational costs and ease of development and implementation, compared to that of WRF-Chem.
Huijnen, V., M. J. Wooster, J. W. Kaiser, D. L. A. Gaveau, J. Flemming, M. Parrington, A. Inness, D. Murdiyarso, B. Main, and M. van Weele (2016), Fire carbon emissions over maritime southeast Asia in 2015 largest since 1997, Scientific Reports, 6, srep26886, doi:10.1038/srep26886.
In September and October 2015 widespread forest and peatland fires burned over large parts of maritime southeast Asia, most notably Indonesia, releasing large amounts of terrestrially-stored carbon into the atmosphere, primarily in the form of CO2, CO and CH4. With a mean emission rate of 11.3 Tg CO2 per day during Sept-Oct 2015, emissions from these fires exceeded the fossil fuel CO2 release rate of the European Union (EU28) (8.9 Tg CO2 per day). Although seasonal fires are a frequent occurrence in the human modified landscapes found in Indonesia, the extent of the 2015 fires was greatly inflated by an extended drought period associated with a strong El Niño. We estimate carbon emissions from the 2015 fires to be the largest seen in maritime southeast Asia since those associated with the record breaking El Niño of 1997. Compared to that event, a much better constrained regional total carbon emission estimate can be made for the 2015 fires through the use of present-day satellite observations of the fire’s radiative power output and atmospheric CO concentrations, processed using the modelling and assimilation framework of the Copernicus Atmosphere Monitoring Service (CAMS) and combined with unique in situ smoke measurements made on Kalimantan.
Koo, J.-H., J. Kim, J. Kim, H. Lee, Y. M. Noh, and Y. G. Lee (2016), Springtime trans-Pacific transport of Asian pollutants characterized by the Western Pacific (WP) pattern, Atmos. Environ., 147, 166–177, doi:10.1016/j.atmosenv.2016.10.007.
Springtime trans-Pacific transport of Asian air pollutants has been investigated in many ways to figure out its mechanism. Based on the Western Pacific (WP) pattern, one of climate variabilities in the Northern Hemisphere known to be associated with the pattern of atmospheric circulation over the North Pacific Ocean, in this study, we characterize the pattern of springtime trans-Pacific transport using long-term satellite measurements and reanalysis datasets. A positive WP pattern is characterized by intensification of the dipole structure between the northern Aleutian Low and the southern Pacific High over the North Pacific. The TOMS/OMI Aerosol Index (Al) and MOPITT CO show the enhancement of Asian pollutant transport across the Pacific during periods of positive WP pattern, particularly between 40 and 50 degrees N. This enhancement is confirmed by high correlations of WP index with AI and CO between 40 and 50 degrees N. To evaluate the influence of the WP pattern, we examine several cases of trans-Pacific transport reported in previous research. Interestingly, most trans-Pacific transport cases are associated with the positive WP pattern. During the period of negative WP pattern, reinforced cyclonic wave breaking is consistently found over the western North Pacific, which obstructs zonal advection across the North Pacific. However, some cases show the trans-Pacific transport of CO in the period of negative WP pattern, implying that the WP pattern is more influential on the transport of particles mostly emitted near similar to 40 degrees N. This study reveals that the WP pattern can be utilized to diagnose the strength of air pollutant transport from East Asia to North America. (C) 2016 Elsevier Ltd. All rights reserved.
Liu, X.-Y., Y. Zhang, Q. Zhang, and K.-B. He (2016), Application of online-coupled WRF/Chem-MADRID in East Asia: Model evaluation and climatic effects of anthropogenic aerosols, Atmospheric Environment, 124, Part B, 321–336, doi:10.1016/j.atmosenv.2015.03.052.
The online-coupled Weather Research and Forecasting model with Chemistry with the Model of Aerosol Dynamics, Reaction, Ionization, and Dissolution (referred to as WRF/Chem-MADRID) is applied to simulate meteorological fields, air quality, and the direct and indirect effects of anthropogenic aerosols over East Asia in four months (January, April, July, and October) in 2008. Model evaluation against available surface and satellite measurements shows that despite some model biases, WRF/Chem-MADRID is able to reproduce reasonably well the spatial and seasonal variations of most meteorological fields and chemical concentrations. Large model biases for chemical concentrations are attributed to uncertainties in emissions and their spatial and vertical allocations, simulated meteorological fields, imperfectness of model representations of aerosol formation processes, uncertainties in the observations based on air pollution index, and the use of a coarse grid resolution. The results show that anthropogenic aerosols can reduce net shortwave flux at the surface by up to 40.5–57.2 W m−2, Temperature at 2-m by up to 0.5–0.8 °C, NO2 photolytic rates by up to 0.06–0.1 min−1 and the planetary boundary layer height by up to 83.6–130.4 m. Anthropogenic aerosols contribute to the number concentrations of aerosols by up to 6.2–8.6 × 104 cm−3 and the surface cloud concentration nuclei at a supersaturation of 0.5% by up to 1.0–1.6 × 104 cm−3. They increase the column cloud droplet number concentrations by up to 3.6–11.7 × 108 cm−2 and cloud optical thickness by up to 19.8–33.2. However, anthropogenic aerosols decrease daily precipitation in most areas by up to 3.9–18.6 mm during the 4 months. These results indicate the importance of anthropogenic aerosols in modulating regional climate changes in East Asia through aerosol direct and indirect effects, as well as the need to further improve the performance of online-coupled models.
Lowry, D., M. E. Lanoiselle, R. E. Fisher, M. Martin, C. M. R. Fowler, J. L. France, I. Y. Hernandez-Paniagua, P. C. Novelli, S. Sriskantharajah, P. O’Brien, N. D. Rata, C. W. Holmes, Z. L. Fleming, K. C. Clemitshaw, G. Zazzeri, M. Pommier, C. A. McLinden, and E. G. Nisbet (2016), Marked long-term decline in ambient CO mixing ratio in SE England, 1997-2014: evidence of policy success in improving air quality, Sci Rep, 6, 25661, doi:10.1038/srep25661.
Atmospheric CO at Egham in SE England has shown a marked and progressive decline since 1997, following adoption of strict controls on emissions. The Egham site is uniquely positioned to allow both assessment and comparison of “clean Atlantic background” air and CO-enriched air downwind from the London conurbation. The decline is strongest (approximately 50 ppb per year) in the 1997-2003 period but continues post 2003. A “local CO increment” can be identified as the residual after subtraction of contemporary background Atlantic CO mixing ratios from measured values at Egham. This increment, which is primarily from regional sources (during anticyclonic or northerly winds) or from the European continent (with easterly air mass origins), has significant seasonality, but overall has declined steadily since 1997. On many days of the year CO measured at Egham is now not far above Atlantic background levels measured at Mace Head (Ireland). The results are consistent with MOPITT satellite observations and “bottom-up” inventory results. Comparison with urban and regional background CO mixing ratios in Hong Kong demonstrates the importance of regional, as opposed to local reduction of CO emission. The Egham record implies that controls on emissions subsequent to legislation have been extremely successful in the UK.
Ojha, N., A. Pozzer, A. Rauthe-Schoech, A. K. Baker, J. Yoon, C. A. M. Brenninkmeijer, and J. Lelieveld (2016), Ozone and carbon monoxide over India during the summer monsoon: regional emissions and transport, Atmos. Chem. Phys., 16(5), 3013–3032, doi:10.5194/acp-16-3013-2016.
We compare in situ measurements of ozone (O-3) and carbon monoxide (CO) profiles from the CARIBIC program with the results from the regional chemistry transport model (WRF-Chem) to investigate the role of local and regional emissions and long-range transport over southern India during the summer monsoon of 2008. WRF-Chem successfully reproduces the general features of O-3 and CO distributions over the South Asian region. However, absolute CO concentrations in the lower troposphere are typically underestimated. Here we investigate the influence of local relative to remote emissions through sensitivity simulations. The influence of 50aEuro-% increased CO emissions over South Asia leads to a significant enhancement (upto 20aEuro-% in July) in upper tropospheric CO in the northern and central Indian regions. Over Chennai in southern India, this causes a 33aEuro-% increase in surface CO during June. However, the influence of enhanced local and regional emissions is found to be smaller (5aEuro-%) in the free troposphere over Chennai, except during September. Local to regional emissions are therefore suggested to play a minor role in the underestimation of CO by WRF-Chem during June-August. In the lower troposphere, a high pollution (O-3: 146.4 +/- 12.8, CO: 136.4 +/- 12.2aEuro-nmol mol(-1)) event (15 July 2008), not reproduced by the model, is shown to be due to transport of photochemically processed air masses from the boundary layer in southern India. A sensitivity simulation combined with backward trajectories indicates that long-range transport of CO to southern India is significantly underestimated, particularly in air masses from the west, i.e., from Central Africa. This study highlights the need for more aircraft-based measurements over India and adjacent regions and the improvement of global emission inventories.
Osman, M. K., D. W. Tarasick, J. Liu, O. Moeini, V. Thouret, V. E. Fioletov, M. Parrington, and P. Nedelec (2016), Carbon monoxide climatology derived from the trajectory mapping of global MOZAIC-IAGOS data, Atmos. Chem. Phys., 16(15), 10263–10282, doi:10.5194/acp-16-10263-2016.
A three-dimensional gridded climatology of carbon monoxide (CO) has been developed by trajectory mapping of global MOZAIC-IAGOS in situ measurements from commercial aircraft data. CO measurements made during aircraft ascent and descent, comprising nearly 41 200 profiles at 148 airports worldwide from December 2001 to December 2012, are used. Forward and backward trajectories are calculated from meteorological reanalysis data in order to map the CO measurements to other locations and so to fill in the spatial domain. This domain-filling technique employs 15 800 000 calculated trajectories to map otherwise sparse MOZAIC-IAGOS data into a quasi-global field. The resulting trajectory-mapped CO data set is archived monthly from 2001 to 2012 on a grid of 5 degrees longitude x 5 degrees latitude x 1 km altitude, from the surface to 14 km altitude. The mapping product has been carefully evaluated, firstly by comparing maps constructed using only forward trajectories and using only backward trajectories. The two methods show similar global CO distribution patterns. The magnitude of their differences is most commonly 10% or less and found to be less than 30% for almost all cases. Secondly, the method has been validated by comparing profiles for individual airports with those produced by the mapping method when data from that site are excluded. While there are larger differences below 2 km, the two methods agree very well between 2 and 10 km with the magnitude of biases within 20 %. Finally, the mapping product is compared with global MOZAIC-IAGOS cruise-level data, which were not included in the trajectory-mapped data set, and with independent data from the NOAA aircraft flask sampling program. The trajectory-mapped MOZAIC-IAGOS CO values show generally good agreement with both independent data sets. Maps are also compared with version 6 data from the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument. Both data sets clearly show major regional CO sources such as biomass burning in Central and southern Africa and anthropogenic emissions in eastern China. While the maps show similar features and patterns, and relative biases are small in the lowermost troposphere, we find differences of similar to 20% in CO volume mixing ratios between 500 and 300 hPa. These upper-tropospheric biases are not related to the mapping procedure, as almost identical differences are found with the original in situ MOZAIC-IAGOS data. The total CO trajectory-mapped MOZAIC-IAGOS column is also higher than the MOPITT CO total column by 12-16 %. The data set shows the seasonal CO cycle over different latitude bands and altitude ranges as well as long-term trends over different latitude bands. We observe a decline in CO over the northern hemispheric extratropics and the tropics consistent with that reported by previous studies using other data sources. We anticipate use of the trajectory-mapped MOZAIC-IAGOS CO data set as an a priori climatology for satellite retrieval and for air quality model validation and initialization.
Rakitin, V., N. Elansky, Y. Shtabkin, A. Skorokhod, E. Grechko, N. Pankratova, and A. Safronov (2016), Comparison results of MOPITT, AIRS and IASI data with ground-based spectroscopic measurements of CO and CH4 total contents, vol. 18, p. 1799. [online] Available from: http://adsabs.harvard.edu/abs/2016EGUGA..18.1799R .
A comparative analysis of satellite and ground-based spectroscopic  measurements of CO and CH4 total content (CO TC) in the atmosphere in the background and polluted conditions (stations of OIAP RAS and NDACC) for the 2010-2015 time-period. The significant correlation between satellite and ground-based CO TC data for all satellite sensors in background conditions was obtained. Also the empirical private transient relationships between satellite CO MOPITT v6 Joint, AIRS v6, IASI MeTop-A products and the data of solar-tracking ground-based spectrometers are analyzed. Significant correlation between satellite and ground-based data of CO TC was obtained for all satellite sensors if measurements were carried out over unpolluted areas (2010-2014). It was shown that for polluted areas IASI MetOp-A and AIRSv6 data underestimate the actual value of CO TC by the factor of 1.5÷ 2.8. The average correlation between satellite and ground-based data increased significantly for the case if the measurement days, when the height of the planetary boundary layer (PBL) was less than 400-500 meters, were excluded from the comparison. This result was obtained for all of the selected sensors and observational sites. To improve the representativeness of the satellite CO TC data for polluted areas it could be recommended to exclude the days with low height of the PBL from the analysis of spatio-temporal variations and subsequent data assimilation (as example for the CO emissions estimating from powerful surface sources). Best correlation (R2≥0.5) in diurnal CH4 TC with ground-based data was found for AIRS v6. This work has supported by the Russian Scientific Foundation under grant №14-47-00049 and partially by the Russian Foundation for Basic Research (grant № 13-05-41395).
Saito, M., H.-S. Kim, A. Ito, T. Yokota, and S. Maksyutov (2016), Enhanced Methane Emissions during Amazonian Drought by Biomass Burning, PLoS One, 11(11), e0166039, doi:10.1371/journal.pone.0166039.
The Amazon is a significant source of atmospheric methane, but little is known about the source response to increasing drought severity and frequency. We investigated satellite observations of atmospheric column-averaged methane for the 2010 drought and subsequent 2011 wet year in the Amazon using an atmospheric inversion scheme. Our analysis indicates an increase in atmospheric methane over the southern Amazon region during the drought, representing an increase in annual emissions relative to the wet year. We attribute the increase to emissions from biomass burning driven by intense drought, combined with carbon monoxide showing seasonal variations corresponding to methane variations. We show that there is probably a strong correspondence between drought and methane emissions in the Amazon.
Sarkar, M., C. Venkataraman, S. Guttikunda, and P. Sadavarte (2016), Indian emissions of technology-linked NMVOCs with chemical speciation: An evaluation of the SAPRC99 mechanism with WRF-CAMx simulations, Atmospheric Environment, 134, 70–83, doi:10.1016/j.atmosenv.2016.03.037.
Non-methane volatile organic compounds (NMVOCs) are important precursors to reactions producing tropospheric ozone and secondary organic aerosols. The present work uses a detailed technology-linked NMVOC emission database for India, along with a standard mapping method to measured NMVOC profiles, to develop speciated NMVOC emissions, which are aggregated into multiple chemical mechanisms used in chemical transport models. The fully speciated NMVOC emissions inventory with 423 constituent species, was regrouped into model-ready reactivity classes of the RADM2, SAPRC99 and CB-IV chemical mechanisms, and spatially distributed at 25 × 25 km2 resolution, using source-specific spatial proxies. Emissions were considered from four major sectors, i.e. industry, transport, agriculture and residential and from non-combustion activities (use of solvents and paints). It was found that residential cooking with biomass fuels, followed by agricultural residue burning in fields and on-road transport, were largest contributors to the highest reactivity group of NMVOC emissions from India. The emissions were evaluated using WRF-CAMx simulations, using the SAPRC99 photochemical mechanism, over India for contrasting months of April, July and October 2010. Modelled columnar abundance of NO2, CO and O3 agreed well with satellite observations both in magnitude and spatial distribution, in the three contrasting months. Evaluation of monthly and spatial differences between model predictions and observations indicates the need for further refinement of the spatial distribution of NOX emissions, spatio-temporal distribution of agricultural residue burning emissions.
Strode, S. A., H. M. Worden, M. Damon, A. R. Douglass, B. N. Duncan, L. K. Emmons, J.-F. Lamarque, M. Manyin, L. D. Oman, J. M. Rodriguez, S. E. Strahan, and S. Tilmes (2016), Interpreting space-based trends in carbon monoxide with multiple models, Atmos. Chem. Phys., 16(11), 7285–7294, doi:10.5194/acp-16-7285-2016.
We use a series of chemical transport model and chemistry climate model simulations to investigate the observed negative trends in MOPITT CO over several regions of the world, and to examine the consistency of time-dependent emission inventories with observations. We find that simulations driven by the MACCity inventory, used for the Chemistry Climate Modeling Initiative (CCMI), reproduce the negative trends in the CO column observed by MOPITT for 2000-2010 over the eastern United States and Europe. However, the simulations have positive trends over eastern China, in contrast to the negative trends observed by MOPITT. The model bias in CO, after applying MOPITT averaging kernels, contributes to the model-observation discrepancy in the trend over eastern China. This demonstrates that biases in a model’s average concentrations can influence the interpretation of the temporal trend compared to satellite observations. The total ozone column plays a role in determining the simulated tropospheric CO trends. A large positive anomaly in the simulated total ozone column in 2010 leads to a negative anomaly in OH and hence a positive anomaly in CO, contributing to the positive trend in simulated CO. These results demonstrate that accurately simulating variability in the ozone column is important for simulating and interpreting trends in CO.
Te, Y., P. Jeseck, B. Franco, E. Mahieu, N. Jones, C. Paton-Walsh, D. T. Griffith, R. R. Buchholz, J. Hadji-Lazaro, D. Hurtmans, and C. Janssen (2016), Seasonal variability of surface and column carbon monoxide over the megacity Paris, high-altitude Jungfraujoch and Southern Hemispheric Wollongong stations, Atmos. Chem. Phys., 16(17), 10911–10925, doi:10.5194/acp-16-10911-2016.
This paper studies the seasonal variation of surface and column CO at three different sites (Paris, Jungfraujoch and Wollongong), with an emphasis on establishing a link between the CO vertical distribution and the nature of CO emission sources. We find the first evidence of a time lag between surface and free tropospheric CO seasonal variations in the Northern Hemisphere. The CO seasonal variability obtained from the total columns and free tropospheric partial columns shows a maximum around March-April and a minimum around September-October in the Northern Hemisphere (Paris and Jungfraujoch). In the Southern Hemisphere (Wollongong) this seasonal variability is shifted by about 6 months. Satellite observations by the IASI-MetOp (Infrared Atmospheric Sounding Interferometer) and MOPITT (Measurements Of Pollution In The Troposphere) instruments confirm this seasonality. Ground-based FTIR (Fourier transform infrared) measurements provide useful complementary information due to good sensitivity in the boundary layer. In situ surface measurements of CO volume mixing ratios at the Paris and Jungfraujoch sites reveal a time lag of the near-surface seasonal variability of about 2 months with respect to the total column variability at the same sites. The chemical transport model GEOS-Chem (Goddard Earth Observing System chemical transport model) is employed to interpret our observations. GEOS-Chem sensitivity runs identify the emission sources influencing the seasonal variation of CO. At both Paris and Jungfraujoch, the surface seasonality is mainly driven by anthropogenic emissions, while the total column seasonality is also controlled by air masses transported from distant sources. At Wollongong, where the CO seasonality is mainly affected by biomass burning, no time shift is observed between surface measurements and total column data.
Xia, Y., Y. Zhao, and C. P. Nielsen (2016), Benefits of China’s efforts in gaseous pollutant control indicated by the bottom-up emissions and satellite observations 2000–2014, Atmospheric Environment, 136, 43–53, doi:10.1016/j.atmosenv.2016.04.013.
To evaluate the effectiveness of national air pollution control policies, the emissions of SO2, NOX, CO and CO2 in China are estimated using bottom-up methods for the most recent 15-year period (2000–2014). Vertical column densities (VCDs) from satellite observations are used to test the temporal and spatial patterns of emissions and to explore the ambient levels of gaseous pollutants across the country. The inter-annual trends in emissions and VCDs match well except for SO2. Such comparison is improved with an optimistic assumption in emission estimation that the emission standards for given industrial sources issued after 2010 have been fully enforced. Underestimation of emission abatement and enhanced atmospheric oxidization likely contribute to the discrepancy between SO2 emissions and VCDs. As suggested by VCDs and emissions estimated under the assumption of full implementation of emission standards, the control of SO2 in the 12th Five-Year Plan period (12th FYP, 2011–2015) is estimated to be more effective than that in the 11th FYP period (2006–2010), attributed to improved use of flue gas desulfurization in the power sector and implementation of new emission standards in key industrial sources. The opposite was true for CO, as energy efficiency improved more significantly from 2005 to 2010 due to closures of small industrial plants. Iron &amp; steel production is estimated to have had particularly strong influence on temporal and spatial patterns of CO. In contrast to fast growth before 2011 driven by increased coal consumption and limited controls, NOX emissions decreased from 2011 to 2014 due to the penetration of selective catalytic/non-catalytic reduction systems in the power sector. This led to reduced NO2 VCDs, particularly in relatively highly polluted areas such as the eastern China and Pearl River Delta regions. In developed areas, transportation is playing an increasingly important role in air pollution, as suggested by the increased ratio of NO2 to SO2 VCDs. For air quality in mega cities, the inter-annual trends in emissions and VCDs indicate that surrounding areas are more influential in NO2 level for Beijing than those for Shanghai.
Yin, Y., P. Ciais, F. Chevallier, G. R. van der Werf, T. Fanin, G. Broquet, H. Boesch, A. Cozic, D. Hauglustaine, S. Szopa, and Y. Wang (2016), Variability of fire carbon emissions in equatorial Asia and its nonlinear sensitivity to El Nino, Geophys. Res. Lett., 43(19), 10472–10479, doi:10.1002/2016GL070971.
The large peatland carbon stocks in the land use change-affected areas of equatorial Asia are vulnerable to fire. Combining satellite observations of active fire, burned area, and atmospheric concentrations of combustion tracers with a Bayesian inversion, we estimated the amount and variability of fire carbon emissions in equatorial Asia over the period 1997-2015. Emissions in 2015 were of 0.510.17Pg carbonless than half of the emissions from the previous 1997 extreme El Nino, explained by a less acute water deficit. Fire severity could be empirically hindcasted from the cumulative water deficit with a lead time of 1 to 2months. Based on CMIP5 climate projections and an exponential empirical relationship found between fire carbon emissions and water deficit, we infer a total fire carbon loss ranging from 12 to 25Pg by 2100 which is a significant positive feedback to climate warming.
Zeb, N., M. Fahim Khokhar, R. Murtaza, A. Noreen, and T. Khalid (2016), Long-Term Changes of Tropospheric Trace Gases over Pakistan Derived From Multiple Satellite Instruments, vol. 41. [online] Available from: http://adsabs.harvard.edu/abs/2016cosp...41E2149Z .
Air pollution is the expected key environmental issue of Pakistan in  coming years due to its ongoing rapid economic growth and this trend suggests only worst air quality over time. In 2014, World bank reported the Pakistan’s urban air quality among the most severe in the world and intimated the government to make improvement in air quality as a priority policy agenda. In addition it is recommended to strengthen the institutional and technical capacity of organizations responsible for air quality management. Therefore, the study is designed to put efforts in highlighting air quality issues. The study will provide first database for tropospheric trace gases over Pakistan. The study aims to analyse tropospheric concentrations of CO, TOC, NO2 and HCHO over Pakistan using multisensory data from January 2005 to January 2014. Spatio-temporal and seasonal variability of tropospheric trace gases is observed over the decade to explore long term trend. Hotspots are identified to see variation of species with latitude and to highlight possible sources of trace gases over the Pakistan. High concentrations of trace gases are mainly observed over the Punjab region, which may be attributed to its metropolitan importance. It is the major agricultural, industrialized and urbanized (nearly 60% of the Pakistan’s population) sector of the country. Overall significant decreasing trend of CO is identified by MOPITT with relative change of 12.4%. Tropospheric ozone column (TOC) showed insignificant increasing trend with temporal increase of 10.4% whereas NO2 exhibited a significant temporal increase of about 28%. For formaldehyde (HCHO), an increase of about 3.8% is calculated for SCIAMACHY data. Well defined seasonal cycles for these trace gases are observed over the whole study period. CO concentrations showed peak in winter months (November/December/January/February) and dip in the months of Summer/Monsoon (June/July/August). In spite of CO, TCO increases gradually in March and peaks in June (Summer/Monsoon). For NO2, the highest concentrations are observed during Winter and the lowest concentrations are found in Summer/Monsoon. Like TOC, the HCHO showed seasonal maxima during summer and minima during winter. The expected sources are the crop residue burning, biomass/fossil fuel burning for heating purposes, urbanization, industrialization and meterological variations. Further focus is made on exploring the association of trace gases in atmosphere and their source identification.
Zhang, L., H. Jiang, X. Lu, and J. Jin (2016a), Comparison analysis of global carbon monoxide concentration derived from SCIAMACHY, AIRS, and MOPITT, Int. J. Remote Sens., 37(21), 5155–5175, doi:10.1080/01431161.2016.1230282.
Observations of carbon monoxide (CO) retrieved from Scanning Imaging Absorption SpectroMeter for Atmospheric Chartography (SCIAMACHY), Measurement of Pollution in the Troposphere (MOPITT), and Atmospheric Infrared Sounder (AIRS) are compared in this article. To better validate the retrieved data from SCIAMCHY, AIRS, and MOPITT, six surface stations at different locations and with various elevations were chosen. The results show these three instruments can all reflect CO spatial distribution well and show same temporal variations of CO concentration as well as six surface station measurements. MOPITT and AIRS have similar retrieval results with correlation coefficients being mostly over 0.70, except for a sixth field station on Crozet Island. The three satellites all have the ability to monitor CO concentration change on land, but SCIAMCHY results show a relatively larger bias than MOPITT and AIRS in low CO concentration areas because of systematic error.
Zhang, Y., X. Zhang, L. Wang, Q. Zhang, F. Duan, and K. He (2016b), Application of WRF/Chem over East Asia: Part I. Model evaluation and intercomparison with MM5/CMAQ, Atmospheric Environment, 124, Part B, 285–300, doi:10.1016/j.atmosenv.2015.07.022.
In this work, the application of the online-coupled Weather Research and Forecasting model with chemistry (WRF/Chem) version 3.3.1 is evaluated over East Asia for January, April, July, and October 2005 and compared with results from a previous application of an offline model system, i.e., the Mesoscale Model and Community Multiple Air Quality modeling system (MM5/CMAQ). The evaluation of WRF/Chem is performed using multiple observational datasets from satellites and surface networks in mainland China, Hong Kong, Taiwan, and Japan. WRF/Chem simulates well specific humidity (Q2) and downward longwave and shortwave radiation (GLW and GSW) with normalized mean biases (NMBs) within 24%, but shows moderate to large biases for temperature at 2-m (T2) (NMBs of −9.8% to 75.6%) and precipitation (NMBs of 11.4–92.7%) for some months, and wind speed at 10-m (WS10) (NMBs of 66.5–101%), for all months, indicating some limitations in the YSU planetary boundary layer scheme, the Purdue Lin cloud microphysics, and the Grell–Devenyi ensemble scheme. WRF/Chem can simulate the column abundances of gases reasonably well with NMBs within 30% for most months but moderately to significantly underpredicts the surface concentrations of major species at all sites in nearly all months with NMBs of −72% to −53.8% for CO, −99.4% to −61.7% for NOx, −84.2% to −44.5% for SO2, −63.9% to −25.2% for PM2.5, and −68.9% to 33.3% for PM10, and aerosol optical depth in all months except for October with NMBs of −38.7% to −16.2%. The model significantly overpredicts surface concentrations of O3 at most sites in nearly all months with NMBs of up to 160.3% and NO 3 - at the Tsinghua site in all months. Possible reasons for large underpredictions include underestimations in the anthropogenic emissions of CO, SO2, and primary aerosol, inappropriate vertical distributions of emissions of SO2 and NO2, uncertainties in upper boundary conditions (e.g., for O3 and CO), missing or inaccurate model representations (e.g., secondary organic aerosol formation, gas/particle partitioning, dust emissions, dry and wet deposition), and inaccurate meteorological fields (e.g., overpredictions in WS10 and precipitation, but underpredictions in T2), as well as the large uncertainties in satellite retrievals (e.g., for column SO2). Comparing to MM5, WRF generally gives worse performance in meteorological predictions, in particular, T2, WS10, GSW, GLW, and cloud fraction in all months, as well as Q2 and precipitation in January and October, due to limitations in the above physics schemes or parameterizations. Comparing to CMAQ, WRF/Chem performs better for surface CO, O3, and PM10 concentrations at most sites in most months, column CO and SO2 abundances, and AOD. It, however, gives poorer performance for surface NOx concentrations at most sites in most months, surface SO2 concentrations at all sites in all months, and column NO2 abundances in January and April. WRF/Chem also gives lower concentrations of most secondary PM and black carbon. Those differences in results are attributed to differences in simulated meteorology, gas-phase chemistry, aerosol thermodynamic and dynamic treatments, dust and sea salt emissions, and wet and dry deposition treatments in both models.
Zhang, Y., C. Hong, K. Yahya, Q. Li, Q. Zhang, and K. He (2016c), Comprehensive evaluation of multi-year real-time air quality forecasting using an online-coupled meteorology-chemistry model over southeastern United States, Atmospheric Environment, 138, 162–182, doi:10.1016/j.atmosenv.2016.05.006.
An online-coupled meteorology-chemistry model, WRF/Chem-MADRID, has been deployed for real time air quality forecast (RT-AQF) in southeastern U.S. since 2009. A comprehensive evaluation of multi-year RT-AQF shows overall good performance for temperature and relative humidity at 2-m (T2, RH2), downward surface shortwave radiation (SWDOWN) and longwave radiation (LWDOWN), and cloud fraction (CF), ozone (O3) and fine particles (PM2.5) at surface, tropospheric ozone residuals (TOR) in O3 seasons (May-September), and column NO2 in winters (December-February). Moderate-to-large biases exist in wind speed at 10-m (WS10), precipitation (Precip), cloud optical depth (COT), ammonium (NH4+), sulfate (SO42−), and nitrate (NO3−) from the IMPROVE and SEARCH networks, organic carbon (OC) at IMPROVE, and elemental carbon (EC) and OC at SEARCH, aerosol optical depth (AOD) and column carbon monoxide (CO), sulfur dioxide (SO2), and formaldehyde (HCHO) in both O3 and winter seasons, column nitrogen dioxide (NO2) in O3 seasons, and TOR in winters. These biases indicate uncertainties in the boundary layer and cloud process treatments (e.g., surface roughness, microphysics cumulus parameterization), emissions (e.g., O3 and PM precursors, biogenic, mobile, and wildfire emissions), upper boundary conditions for all major gases and PM2.5 species, and chemistry and aerosol treatments (e.g., winter photochemistry, aerosol thermodynamics). The model shows overall good skills in reproducing the observed multi-year trends and inter-seasonal variability in meteorological and radiative variables such as T2, WS10, Precip, SWDOWN, and LWDOWN, and relatively well in reproducing the observed trends in surface O3 and PM2.5, but relatively poor in reproducing the observed column abundances of CO, NO2, SO2, HCHO, TOR, and AOD. The sensitivity simulations using satellite-constrained boundary conditions for O3 and CO show substantial improvement for both spatial distribution and domain-mean performance statistics. The model’s forecasting skills for air quality can be further enhanced through improving model inputs (e.g., anthropogenic emissions for urban areas and upper boundary conditions of chemical species), meteorological forecasts (e.g., WS10, Precip) and meteorologically-dependent emissions (e.g., biogenic and wildfire emissions), and model physics and chemical treatments (e.g., gas-phase chemistry in winter conditions, cloud processes and their interactions with radiation and aerosol).
Zhang, Y., J. He, S. Zhu, and B. Gantt (2016d), Sensitivity of simulated chemical concentrations and aerosol-meteorology interactions to aerosol treatments and biogenic organic emissions in WRF/Chem, J. Geophys. Res. Atmos., 2016JD024882, doi:10.1002/2016JD024882.
Coupled air quality and climate models can predict aerosol concentrations and properties, as well as aerosol direct and indirect effects that depend on aerosol chemistry and microphysics treatments. In this study, Weather Research and Forecasting with Chemistry (WRF/Chem) simulations are conducted over continental U.S. (CONUS) for January and July 2001 with the same gas-phase mechanism (CB05) but three aerosol modules (Modal Aerosol Dynamics Model for Europe/Secondary Organic Aerosol Model (MADE/SORGAM), Model for Simulating Aerosol Interactions and Chemistry (MOSAIC), and Model of Aerosol Dynamics, Reaction, Ionization and Dissolution (MADRID)) to examine the impacts of aerosol treatments on predictions of aerosols and their effects on cloud properties and radiation. The simulations with the three aerosol modules give similar domain mean predictions of surface PM2.5 concentrations but exhibit a strong spatial variation in magnitudes with large differences in eastern U.S. Large discrepancies are found in the predicted concentrations of sulfate and organic matter due to different treatments in secondary inorganic and secondary organic aerosol (SOA) formation. In particular, the nucleation calculation in MADE/SORGAM causes mass buildup of sulfate which results in much higher sulfate concentrations that those predicted by WRF/Chem with the other two aerosol modules. Different PM mass concentrations and size representations lead to differences in the predicted aerosol number concentrations. The above differences in PM concentrations lead to large differences in simulated condensation nuclei (CCN) and cloud properties in both months. The simulated ranges of domain mean are (1.9–14.3) × 109 m−3 and (1.4–5.4) × 109 m−3 for PM2.5 number concentration, (1.6–3.9) × 108 cm−2 and (1.9–3.9) × 108 cm−2 for CCN, 102.9–208.2 cm−3 and 143.7–202.2 cm−3 for column cloud droplet number concentration (CDNC), and 4.5–6.4 and 3.6–6.7 for cloud optical depths (COT) in January and July, respectively. The sensitivity simulation for July 2001 using online biogenic emissions increases isoprene concentrations but decreases terpene concentrations, leading to a domain mean increase in O3 (1.5 ppb) and a decrease in biogenic SOA (−0.07 µg m−3) and PM2.5 (−0.2 µg m−3). Anthropogenic emissions contribute to O3, biogenic SOA (BSOA), and PM2.5 concentrations by 38.0%, 44.2%, and 53.6% domain mean and by up to 78.5%, 89.7%, and 96.3%, respectively, indicating that a large fraction of BSOA is controllable through controlling atmospheric oxidant levels in CONUS. Anthropogenic emissions also contribute to a decrease in downward shortwave flux at ground surface (−5.8 W m−2), temperature at 2 m (−0.05°C), wind speed at 10 m (−0.02 m s−1), planetary boundary layer height (−6.6 m), and precipitation (−0.08 mm), as well as an increase in CCN (+5.7 × 10−7 cm−2), in-cloud CDNC (+40.4 cm−3), and COT (+0.6). This work indicates the need for an accurate representation of several aerosol processes such as SOA formation and aerosol-cloud interactions in simulating aerosol direct and indirect effects in the online-coupled models.

2015

Andersson, E., M. Kahnert, and A. Devasthale (2015), Methodology for evaluating lateral boundary conditions in the regional chemical transport model MATCH (v5.5.0) using combined satellite and ground-based observations, Geosci. Model Dev., 8(11), 3747–3763, doi:10.5194/gmd-8-3747-2015.
Hemispheric transport of air pollutants can have a significant impact on regional air quality, as well as on the effect of air pollutants on regional climate. An accurate representation of hemispheric transport in regional chemical transport models (CTMs) depends on the specification of the lateral boundary conditions (LBCs). This study focuses on the methodology for evaluating LBCs of two moderately long-lived trace gases, carbon monoxide (CO) and ozone (O-3), for the European model domain and over a 7-year period, 2006-2012. The method is based on combining the use of satellite observations at the lateral boundary with the use of both satellite and in situ ground observations within the model domain. The LBCs are generated by the global European Monitoring and Evaluation Programme Meteorological Synthesizing Centre - West (EMEP MSC-W) model; they are evaluated at the lateral boundaries by comparison with satellite observations of the Terra-MOPITT (Measurements Of Pollution In The Troposphere) sensor (CO) and the Aura-OMI (Ozone Monitoring Instrument) sensor (O-3). The LBCs from the global model lie well within the satellite uncertainties for both CO and O-3. The biases increase below 700 hPa for both species. However, the satellite retrievals below this height are strongly influenced by the a priori data; hence, they are less reliable than at, e.g. 500 hPa. CO is, on average, underestimated by the global model, while O-3 tends to be overestimated during winter, and underestimated during summer. A regional CTM is run with (a) the validated monthly climatological LBCs from the global model; (b) dynamical LBCs from the global model; and (c) constant LBCs based on in situ ground observations near the domain boundary. The results are validated against independent satellite retrievals from the Aqua-AIRS (Atmospheric InfraRed Sounder) sensor at 500 hPa, and against in situ ground observations from the Global Atmospheric Watch (GAW) network. It is found that (i) the use of LBCs from the global model gives reliable in-domain results for O-3 and CO at 500 hPa. Taking AIRS retrievals as a reference, the use of these LBCs substantially improves spatial pattern correlations in the free troposphere as compared to results obtained with fixed LBCs based on ground observations. Also, the magnitude of the bias is reduced by the new LBCs for both trace gases. This demonstrates that the validation methodology based on using satellite observations at the domain boundary is sufficiently robust in the free troposphere. (ii) The impact of the LBCs on ground concentrations is significant only at locations in close proximity to the domain boundary. As the satellite data near the ground mainly reflect the a priori estimate used in the retrieval procedure, they are of little use for evaluating the effect of LBCs on ground concentrations. Rather, the evaluation of ground-level concentrations needs to rely on in situ ground observations. (iii) The improvements of dynamic over climatological LBCs become most apparent when using accumulated ozone over threshold 40 ppb (AOT40) as a metric. Also, when focusing on ground observations taken near the inflow boundary of the model domain, one finds that the use of dynamical LBCs yields a more accurate representation of the seasonal variation, as well as of the variability of the trace gas concentrations on shorter timescales.
Badia, A., and O. Jorba (2015), Gas-phase evaluation of the online NMMB/BSC-CTM model over Europe for 2010 in the framework of the AQMEII-Phase2 project, Atmospheric Environment, doi:10.1016/j.atmosenv.2014.05.055. [online] Available from: http://www.sciencedirect.com/science/article/pii/S1352231014004026 .
The Air Quality Model Evaluation International Initiative Phase2 aims to intercompare online coupled regional-scale models over North America and Europe. The NMMB/BSC Chemical Transport Model (NMMB/BSC-CTM) is a fully online integrated system for meso- to global-scale applications under development at the Barcelona Supercomputing Center. The NMMB/BSC-CTM is applied to Europe for the year 2010 in the framework of the AQMEII-Phase2 intercomparison exercise. This paper presents a spatial, temporal and vertical evaluation of the gas-phase model results. This is the first time that the model has been evaluated on a regional scale over a whole annual cycle. The model is compared with available ground-based monitoring stations for relevant reactive gases, ozonesondes, and OMI and MOPITT satellite retrievals of NO2 and CO. A comparative analysis of the present results and several European model evaluations is also presented here.  The seasonal cycle for O3, NO2, SO2 and CO is successfully reproduced by the model. The O3 daily mean and daily maximum correlations for the analysed period are r = 0.68 and r = 0.75, respectively. The OMI tropospheric NO2 column retrievals are well reproduced, capturing the most polluted areas over Europe throughout the whole year. Modelled SO2 and CO surface concentrations are generally underestimated, especially during the winter months. Two different vertical configurations of the model (24 and 48 vertical layers) are also analysed. Although model results are very similar, the simulation configured with 48 vertical layers provides better results regarding surface O3 concentrations during summer. Compared to previous model evaluations, the NMMB/BSC-CTM’s performance corresponds to state-of-the-art regional air quality models.
Barre, J., B. Gaubert, A. F. J. Arellano, H. M. Worden, D. P. Edwards, M. N. Deeter, J. L. Anderson, K. Raeder, N. Collins, S. Tilmes, G. Francois, C. Clerbaux, L. K. Emmons, G. G. Pfister, P.-F. Coheur, and D. Hurtmans (2015), Assessing the impacts of assimilating IASI and MOPITT CO retrievals using CESM-CAM-chem and DART, J. Geophys. Res.-Atmos., 120(19), doi:10.1002/2015JD023467.
We show the results and evaluation with independent measurements from assimilating both MOPITT (Measurements Of Pollution In The Troposphere) and IASI (Infrared Atmospheric Sounding Interferometer) retrieved profiles into the Community Earth System Model (CESM). We used the Data Assimilation Research Testbed ensemble Kalman filter technique, with the full atmospheric chemistry CESM component Community Atmospheric Model with Chemistry. We first discuss the methodology and evaluation of the current data assimilation system with coupled meteorology and chemistry data assimilation. The different capabilities of MOPITT and IASI retrievals are highlighted, with particular attention to instrument vertical sensitivity and coverage and how these impact the analyses. MOPITT and IASI CO retrievals mostly constrain the CO fields close to the main anthropogenic, biogenic, and biomass burning CO sources. In the case of IASI CO assimilation, we also observe constraints on CO far from the sources. During the simulation time period (June and July 2008), CO assimilation of both instruments strongly improves the atmospheric CO state as compared to independent observations, with the higher spatial coverage of IASI providing better results on the global scale. However, the enhanced sensitivity of multispectral MOPITT observations to near surface CO over the main source regions provides synergistic effects at regional scales.
Barré, J., D. Edwards, H. Worden, A. Da Silva, and W. Lahoz (2015), On the feasibility of monitoring carbon monoxide in the lower troposphere from a constellation of Northern Hemisphere geostationary satellites. (Part 1), Atmospheric Environment, 113, 63–77, doi:10.1016/j.atmosenv.2015.04.069.
By the end of the current decade, there are plans to deploy several geostationary Earth orbit (GEO) satellite missions for atmospheric composition over North America, East Asia and Europe with additional missions proposed. Together, these present the possibility of a constellation of geostationary platforms to achieve continuous time-resolved high-density observations over continental domains for mapping pollutant sources and variability at diurnal and local scales. In this paper, we use a novel approach to sample a very high global resolution model (GEOS-5 at 7 km horizontal resolution) to produce a dataset of synthetic carbon monoxide pollution observations representative of those potentially obtainable from a GEO satellite constellation with predicted measurement sensitivities based on current remote sensing capabilities. Part 1 of this study focuses on the production of simulated synthetic measurements for air quality OSSEs (Observing System Simulation Experiments). We simulate carbon monoxide nadir retrievals using a technique that provides realistic measurements with very low computational cost. We discuss the sampling methodology: the projection of footprints and areas of regard for geostationary geometries over each of the North America, East Asia and Europe regions; the regression method to simulate measurement sensitivity; and the measurement error simulation. A detailed analysis of the simulated observation sensitivity is performed, and limitations of the method are discussed. We also describe impacts from clouds, showing that the efficiency of an instrument making atmospheric composition measurements on a geostationary platform is dependent on the dominant weather regime over a given region and the pixel size resolution. These results demonstrate the viability of the “instrument simulator” step for an OSSE to assess the performance of a constellation of geostationary satellites for air quality measurements. We describe the OSSE results in a follow up paper (Part 2 of this study).
Bhattacharjee, P. S., R. P. Singh, and P. Nedelec (2015), Vertical profiles of carbon monoxide and ozone from MOZAIC aircraft over Delhi, India during 2003-2005, Meteorol. Atmos. Phys., 127(2), 229–240, doi:10.1007/s00703-014-0349-x.
The Indo-Gangetic Plains is one of the most densely populated regions in the world and associated with large anthropogenic pollutants. Aircraft measurements of two such pollutants, ozone (O-3) and carbon monoxide (CO) over Delhi, an urban location are analyzed to study monthly and seasonal variations. Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) vertical profile data during 2003-2005 are used in the present study. O-3 over Delhi exhibits a lower tropospheric (surface to 850 mb) high value during post-monsoon (October and November) and winter (December-February) seasons, upper tropospheric (above 400 mb) enhancement during pre-monsoon and a zone of high values in the mid-troposphere (700-400 mb) during monsoon. The anthropogenic emissions show high CO concentrations below 800 mb during winter and pre-monsoon seasons in addition to transported CO in the upper atmosphere during pre-monsoon. During winter season, convective activities are suppressed as a result O-3 and CO concentrations are higher near surface, while during summer season, surface air masses enhance levels of H2O, CO and other trace gases are lifted and subsequently mixed into the large scale circulation that enhance mixing ratios of many trace gases in the upper level anticyclones. MOZAIC observed vertical O-3 profiles are compared with three chemistry-climate coupled models from the Coupled Model Inter-comparison Project Phase5 (CMIP5) with interactive O-3 chemistry. All the models show good agreement with MOZAIC during pre-monsoon, with large biases during winter and monsoon seasons. Finally, monthly variations of MOZAIC observed CO show a good comparison with AIRS and MOPITT satellite data.
Bloom, A. A., J. Worden, Z. Jiang, H. Worden, T. Kurosu, C. Frankenberg, and D. Schimel (2015), Remote-sensing constraints on South America fire traits by Bayesian fusion of atmospheric and surface data, Geophys. Res. Lett., 42(4), 2014GL062584, doi:10.1002/2014GL062584.
Satellite observations reveal substantial burning during the 2007 and 2010 tropical South America fire season, with both years exhibiting similar total burned area. However, 2010 CO fire emissions, based on satellite CO concentration measurements, were substantially lower (−28%), despite the once-in-a-century drought in 2010. We use Bayesian inference with satellite measurements of CH4 and CO concentrations and burned area to quantify shifts in combustion characteristics in 2010 relative to 2007. We find an 88% probability in reduced combusted biomass density associated with the 2010 fires and an 82% probability of lower fire carbon losses in 2010 relative to 2007. Higher combustion efficiency was a smaller contributing factor to the reduced 2010 CO emissions. The reduction in combusted biomass density is consistent with a reduction (4–6%) in Global Ozone Monitoring Experiment 2 solar-induced fluorescence (a proxy for gross primary production) during the preceding months and a potential reduction in biomass (≤8.3%) due to repeat fires.
Choi, Y., and A. H. Souri (2015), Seasonal behavior and long-term trends of tropospheric ozone, its precursors and chemical conditions over Iran: A view from space, Atmospheric Environment, 106, 232–240, doi:10.1016/j.atmosenv.2015.02.012.
To identify spatial and temporal variations over the Iranian region, this study analyzed tropospheric formaldehyde (HCHO) and nitrogen dioxide (NO2) columns from Ozone Monitoring Instrument (OMI), carbon monoxide (CO) columns from the Measurement of Pollution in the Troposphere (MOPITT), and tropospheric column O3 (TCO) from OMI/MLS (Microwave Limb Sounder) satellites from 2005 to 2012. The study discovered high levels of HCHO (∼12 × 1015 molec./cm2) from plant isoprene emissions in the air above parts of the northern forest of Iran during the summer and from the oxidation of HCHO precursors emitted from petrochemical industrial facilities and biomass burning in South West Iran. This study showed that maximum NO2 levels (∼18 × 1015 molec./cm2) were concentrated in urban cities, indicating the predominance of anthropogenic sources. The results indicate that maximum concentrations were found in the winter, mainly because of weaker local winds and higher heating fuel consumption, in addition to lower hydroxyl radicals (OH). The high CO concentrations (∼2 × 1018 molec./cm2) in the early spring were inferred to mainly originate from a strong continental air mass from anthropogenic CO “hotspots” including regions around Caspian Sea, Europe, and North America, although the external sources of CO were partly suppressed by the Arabian anticyclone and topographic barriers. Variations in the TCO were seen to peak during the summer (∼40 DU), due to intensive solar radiation and stratospheric sources. This study also examined long-term trends in TCO and its precursors over a period of eight years in five urban cities in Iran. To perform the analysis, we estimated seasonal changes and inter-seasonal variations using least-squares harmonic estimation (LS-HE), which reduced uncertainty in the trend by 5–15%. The results showed significant increases in the levels of HCHO (∼0.08 ± 0.06 × 1015 molec./cm2 yr−1), NO2 (∼0.08 ± 0.02 × 1015 molec./cm2 yr−1), and peak annual TCO (∼0.59 ± 0.56 DU yr−1) but decreases in minimum annual TCO (∼−0.42 ± 0.60 DU yr−1) caused by an increase in NO2 species and annual CO (∼−0.95 ± 0.41 × 1016 molec./cm2 yr−1) partly resulting from the transport of reduced CO. The time series of the HCHO/NO2 column ratio (a proxy for the chemical conditions) indicated that during the last decade, the cities of Tehran, Ahvaz, and Isfahan exhibited steady chemical conditions while Tabriz and Mashhad exhibited a change from NOx-saturated/mixed to more NOx-sensitive chemical conditions.
Deeter, M. N., D. P. Edwards, J. C. Gille, and H. M. Worden (2015), Information content of MOPITT CO profile retrievals: Temporal and geographical variability, J. Geophys. Res.-Atmos., 120(24), 12723–12738, doi:10.1002/2015JD024024.
Satellite measurements of tropospheric carbon monoxide (CO) enable a wide array of applications including studies of air quality and pollution transport. The MOPITT (Measurements of Pollution in the Troposphere) instrument on the Earth Observing System Terra platform has been measuring CO concentrations globally since March 2000. As indicated by the Degrees of Freedom for Signal (DFS), the standard metric for trace-gas retrieval information content, MOPITT retrieval performance varies over a wide range. We show that both instrumental and geophysical effects yield significant geographical and temporal variability in MOPITT DFS values. Instrumental radiance uncertainties, which describe random errors (or “noise”) in the calibrated radiances, vary over long time scales (e.g., months to years) and vary between the four detector elements of MOPITT’s linear detector array. MOPITT retrieval performance depends on several factors including thermal contrast, fine-scale variability of surface properties, and CO loading. The relative importance of these various effects is highly variable, as demonstrated by analyses of monthly mean DFS values for the United States and the Amazon Basin. An understanding of the geographical and temporal variability of MOPITT retrieval performance is potentially valuable to data users seeking to limit the influence of the a priori through data filtering. To illustrate, it is demonstrated that calculated regional-average CO mixing ratios may be improved by excluding observations from a subset of pixels in MOPITT’s linear detector array.
Field, R. D., M. Luo, D. Kim, A. D. Del Genio, A. Voulgarakis, and J. Worden (2015), Sensitivity of simulated tropospheric CO to subgrid physics parameterization: A case study of Indonesian biomass burning emissions in 2006, J. Geophys. Res. Atmos., 120(22), 2015JD023402, doi:10.1002/2015JD023402.
Recent cumulus and turbulence parameterization changes to the NASA GISS ModelE2 have improved representation of the Madden-Julian Oscillation and low cloud distribution, but their effect on composition-related quantities is not known. In this study, we simulate the vertical transport of carbon monoxide (CO) from uncontrolled biomass burning in Indonesia in late 2006, during which uniquely high CO was detected in the upper troposphere. Two configurations of ModelE2, one without the changes (AR5) and one with the changes (AR5′), are used for an ensemble simulation of the transport of CO from the biomass burning. The simulation results are evaluated against new CO profiles retrieved jointly from the Aura Tropospheric Emission Spectrometer and the Microwave Limb Sounder. Modeled upper tropospheric CO using the AR5 physics was unrealistically high. The AR5′ physics suppress deep convection that reaches near the tropopause, reducing vertical transport of CO to the upper troposphere and bringing the model into better agreement with satellite CO. In this regard, the most important changes were related to the strength of entrainment of environmental air into the convective column, the strength of re-evaporation above cloud base, and a negative plume buoyancy threshold based on density temperature. This study illustrates how individual, noncomposition model changes can lead to significantly different modeled composition, which in this case improved agreement with satellite retrievals. This study also illuminates the potential usefulness of CO satellite observations in constraining unobservable processes in general circulation models.
George, M., C. Clerbaux, I. Bouarar, P.-F. Coheur, M. N. Deeter, D. P. Edwards, G. Francis, J. C. Gille, J. Hadji-Lazaro, D. Hurtmans, A. Inness, D. Mao, and H. M. Worden (2015), An examination of the long-term CO records from MOPITT and IASI: comparison of retrieval methodology, Atmos. Meas. Tech., 8(10), 4313–4328, doi:10.5194/amt-8-4313-2015.
Carbon monoxide (CO) is a key atmospheric compound that can be remotely sensed by satellite on the global scale. Fifteen years of continuous observations are now available from the MOPITT/Terra mission (2000 to present). Another 15 and more years of observations will be provided by the IASI/MetOp instrument series (2007-2023 >). In order to study long-term variability and trends, a homogeneous record is required, which is not straightforward as the retrieved quantities are instrument and processing dependent. The present study aims at evaluating the consistency between the CO products derived from the MOPITT and IASI missions, both for total columns and vertical profiles, during a 6-year overlap period (2008-2013). The analysis is performed by first comparing the available 2013 versions of the retrieval algorithms (v5T for MOPITT and v20100815 for IASI), and second using a dedicated reprocessing of MOPITT CO profiles and columns using the same a priori information as the IASI product. MOPITT total columns are generally slightly higher over land (bias ranging from 0 to 13 %) than IASI data. When IASI and MOPITT data are retrieved with the same a priori constraints, correlation coefficients are slightly improved. Large discrepancies (total column bias over 15 %) observed in the Northern Hemisphere during the winter months are reduced by a factor of 2 to 2.5. The detailed analysis of retrieved vertical profiles compared with collocated aircraft data from the MOZAIC-IAGOS network, illustrates the advantages and disadvantages of a constant vs. a variable a priori. On one hand, MOPITT agrees better with the aircraft profiles for observations with persisting high levels of CO throughout the year due to pollution or seasonal fire activity (because the climatology-based a priori is supposed to be closer to the real atmospheric state). On the other hand, IASI performs better when unexpected events leading to high levels of CO occur, due to a larger variability associated with the a priori.
Gonzi, S., P. I. Palmer, R. Paugam, M. Wooster, and M. N. Deeter (2015), Quantifying pyroconvective injection heights using observations of fire energy: sensitivity of spaceborne observations of carbon monoxide, Atmos. Chem. Phys., 15(8), 4339–4355, doi:10.5194/acp-15-4339-2015.
We use observations of active fire area and fire radiative power (FRP) from the NASA Moderate Resolution Imaging Spectroradiometers (MODIS), together with a parameterized plume rise model, to estimate biomass burning injection heights during 2006. We use these injection heights in the GEOS-Chem (Goddard Earth Observing System Chemistry) atmospheric chemistry transport model to vertically distribute biomass burning emissions of carbon monoxide (CO) and to study the resulting atmospheric distribution. For 2006, we use over half a million FRP and fire area observations as input to the plume rise model. We find that convective heat fluxes and active fire area typically lie in the range of 1-100 k W m(-2) and 0.001-100 ha, respectively, although in rare circumstances the convective heat flux can exceed 500 k W m(-2). The resulting injection heights have a skewed probability distribution with approximately 80% of the injections remaining within the local boundary layer (BL), with occasional injection height exceeding 8 km. We do not find a strong correlation between the FRP-inferred surface convective heat flux and the resulting injection height, with environmental conditions often acting as a barrier to rapid vertical mixing even where the convective heat flux and active fire area are large. We also do not find a robust relationship between the underlying burnt vegetation type and the injection height. We find that CO columns calculated using the MODIS-inferred injection height (MODISINJ) are typically -9 to +6% different to the control calculation in which emissions are emitted into the BL, with differences typically largest over the point of emission. After applying MOPITT (Measurement of Pollution in the Tropo-sphere) v5 scene-dependent averaging kernels we find that we are much less sensitive to our choice of injection height profile. The differences between the MOPITT and the model CO columns (max bias approximate to 50 %), due largely to uncertainties in emission inventories, are much larger than those introduced by the injection heights. We show that including a realistic diurnal variation in FRP (peaking in the afternoon) or accounting for subgrid-scale emission errors does not alter our main conclusions. Finally, we use a Bayesian maximum a posteriori approach constrained by MOPITT CO profiles to estimate the CO emissions but because of the inherent bias between model and MOPITT we find little impact on the resulting emission estimates. Studying the role of pyroconvection in the distribution of gases and particles in the atmosphere using global MOPITT CO observations (or any current spaceborne measurement of the atmosphere) is still associated with large errors, with the exception of a small subset of large fires and favourable environmental conditions, which will consequently lead to a bias in any analysis on a global scale.
ul-Haq, Z., A. D. Rana, M. Ali, K. Mahmood, S. Tariq, and Z. Qayyum (2015), Carbon monoxide (CO) emissions and its tropospheric variability over Pakistan using satellite-sensed data, Adv. Space Res., 56(4), 583–595, doi:10.1016/j.asr.2015.04.026.
This study presents major anthropogenic sources of carbon monoxide (CO) in Pakistan and discusses the spatio-temporal variability of tropospheric CO over Pakistan and neighboring regions of Afghanistan, India and Iran for a period from 2003 to 2012 using satellite-sensed (AIRS/AMSU) data. The results show a large spatio-temporal variability of CO over the study region mostly associated with anthropogenic activities such as crop residue burning, vehicular transport, and electricity and energy generation, and local meteorology. The annual mean value of tropospheric CO is observed to be 115 +/- 2 ppbv that remains almost steady during the study period with decadal increase of only 2%. Due to more anthropogenic emissions of CO and its transport, the eastern zone shows a higher average value of 122 +/- 2 ppbv with 2.7% decadal increase than the western zone (111 +/- 3 ppbv with 1.4% decadal increase). Elevated concentrations of CO have been observed over the Indo-Gangetic Basin, Lahore, Karachi, and Delhi. During the study period large fluctuations in CO mean monthly values are found ranging from 99 ppbv to 131 ppbv. The fact that, in spite of a large increase in the CO emissions from 2003 to 2012, its average concentration remains almost stable indicates that a large scale regional transport contributes substantially to the tropospheric CO. Carbon monoxide concentrations exhibit a strong seasonal pattern with maximum amplitude in spring and minimum in autumn. July is found to have the highest decadal increasing trend of 13% followed by August at 8%, whereas May has the highest decreasing trend of -8% followed by November at -4.4%. (C) 2015 COSPAR. Published by Elsevier Ltd. All rights reserved.
He, J., Y. Zhang, T. Glotfelty, R. He, R. Bennartz, J. Rausch, and K. Sartelet (2015), Decadal simulation and comprehensive evaluation of CESM/CAM5.1 with advanced chemistry, aerosol microphysics, and aerosol-cloud interactions, J. Adv. Model. Earth Syst., n/a-n/a, doi:10.1002/2014MS000360.
Earth system models have been used for climate predictions in recent years due to their capabilities to include biogeochemical cycles, human impacts, as well as coupled and interactive representations of Earth system components (e.g., atmosphere, ocean, land, and sea ice). In this work, the Community Earth System Model (CESM) with advanced chemistry and aerosol treatments, referred to as CESM-NCSU, is applied for decadal (2001-2010) global climate predictions. A comprehensive evaluation is performed focusing on the atmospheric component- the Community Atmosphere Model version 5.1 (CAM5.1) by comparing simulation results with observations/reanalysis data and CESM ensemble simulations from the Coupled Model Intercomparison Project phase 5 (CMIP5). The improved model can predict most meteorological and radiative variables relatively well with normalized mean biases (NMBs) of -14.1% to -9.7% and 0.7% to 10.8%, respectively, although temperature at 2-m (T2) is slightly underpredicted. Cloud variables such as cloud fraction (CF) and precipitating water vapor (PWV) are well predicted, with NMBs of -10.5% to 0.4%, whereas cloud condensation nuclei (CCN), cloud liquid water path (LWP), and cloud optical thickness (COT) are moderately-to-largely underpredicted, with NMBs of -82.2% to -31.2%, and cloud droplet number concentration (CDNC) is overpredictd by 26.7%. These biases indicate the limitations and uncertainties associated with cloud microphysics (e.g., resolved clouds and subgrid-scale cumulus clouds). Chemical concentrations over the continental U.S. (CONUS) (e.g., SO42-, Cl-, OC, and PM2.5) are reasonably well predicted with NMBs of -12.8% to -1.18%. Concentrations of SO2, SO42-, and PM10 are also reasonably well predicted over Europe with NMBs of -20.8% to -5.2%, so are predictions of SO2 concentrations over the East Asia with an NMB of -18.2%, and the tropospheric ozone residual (TOR) over the globe with an NMB of -3.5%. Most meteorological and radiative variables predicted by CESM-NCSU agree well overall with those predicted by CESM-CMIP5. The performance of LWP and AOD predicted by CESM-NCSU is better than that of CESM-CMIP5 in terms of model bias and correlation coefficients. Large biases for some chemical predictions can be attributed to uncertainties in the emissions of precursor gases (e.g., SO2, NH3, and NOx) and primary aerosols (black carbon and primary organic matter) as well as uncertainties in formulations of some model components (e.g., online dust and sea-salt emissions, secondary organic aerosol formation, and cloud microphysics). Comparisons of CESM simulation with baseline emissions and 20% of anthropogenic emissions from the baseline emissions indicate that anthropogenic gas and aerosol species can decrease downwelling shortwave radiation (FSDS) by 4.7 W m−2 (or by 2.9%) and increase SWCF by 3.2 W m−2 (or by 3.1%) in the global mean. This article is protected by copyright. All rights reserved.
Inness, A., A.-M. Blechschmidt, I. Bouarar, S. Chabrillat, M. Crepulja, R. J. Engelen, H. Eskes, J. Flemming, A. Gaudel, F. Hendrick, V. Huijnen, L. Jones, J. Kapsomenakis, E. Katragkou, A. Keppens, B. Langerock, M. de Maziere, D. Melas, M. Parrington, V. H. Peuch, M. Razinger, A. Richter, M. G. Schultz, M. Suttie, V. Thouret, M. Vrekoussis, A. Wagner, and C. Zerefos (2015), Data assimilation of satellite-retrieved ozone, carbon monoxide and nitrogen dioxide with ECMWF’s Composition-IFS, Atmos. Chem. Phys., 15(9), 5275–5303, doi:10.5194/acp-15-5275-2015.
Daily global analyses and 5-day forecasts are generated in the context of the European Monitoring Atmospheric Composition and Climate (MACC) project using an extended version of the Integrated Forecasting System (IFS) of the European Centre for Medium-Range Weather Forecasts (ECMWF). The IFS now includes modules for chemistry, deposition and emission of reactive gases, aerosols, and greenhouse gases, and the 4-dimensional variational data assimilation scheme makes use of multiple satellite observations of atmospheric composition in addition to meteorological observations. This paper describes the data assimilation setup of the new Composition-IFS (C-IFS) with respect to reactive gases and validates analysis fields of ozone (O-3), carbon monoxide (CO), and nitrogen dioxide (NO2) for the year 2008 against independent observations and a control run without data assimilation. The largest improvement in CO by assimilation of Measurements of Pollution in the Troposphere (MOPITT) CO columns is seen in the lower troposphere of the Northern Hemisphere (NH) extratropics during winter, and during the South African biomass-burning season. The assimilation of several O-3 total column and stratospheric profile retrievals greatly improves the total column, stratospheric and upper tropospheric O-3 analysis fields relative to the control run. The impact on lower tropospheric ozone, which comes from the residual of the total column and stratospheric profile O-3 data, is smaller, but nevertheless there is some improvement particularly in the NH during winter and spring. The impact of the assimilation of tropospheric NO2 columns from the Ozone Monitoring Instrument (OMI) is small because of the short lifetime of NO2, suggesting that NO2 observations would be better used to adjust emissions instead of initial conditions. The results further indicate that the quality of the tropospheric analyses and of the stratospheric ozone analysis obtained with the C-IFS system has improved compared to the previous “coupled” model system of MACC.
Jena, C., S. D. Ghude, G. G. Pfister, D. M. Chate, R. Kumar, G. Beig, D. E. Surendran, S. Fadnavis, and D. M. Lal (2015), Influence of springtime biomass burning in South Asia on regional ozone (O3): A model based case study, Atmospheric Environment, 100, 37–47, doi:10.1016/j.atmosenv.2014.10.027.
In this study, for the first time, the influence of springtime (MAM) biomass burning in South Asia on regional ozone (O3) distribution has been evaluated using a regional chemical transport model (WRF-Chem) and the Fire Inventory from NCAR (FINNv1). Model results are compared with satellite retrievals of tropospheric column amounts of carbon monoxide (CO) from MOPITT and nitrogen dioxide (NO2) from OMI. With daily varying emissions, the model captures reasonably well the satellite-derived temporal variations in CO and NO2 (index of agreement (R) for CO is 0.83 and for NO2 is 0.76), indicating the effectiveness of the model in estimating the overall fire impact on a regional scale. Simulated tropospheric NO2 concentration shows better agreement with the magnitude of observed NO2 when FINNv1 NOx emissions are reduced by a factor of 2.2 over the model domain. A clear increase in CO and NO2 levels over Burma (35–60%), Central India (15–30%), the Indo-Gangetic (15–25%) region and the Bay of Bengal (15–40%) are simulated with fire emissions. The model results are also used to quantify the net O3 production from fires. Calculated O3 productions are up to 4 ppb h−1 over inland and up to 0.1 ppb h−1 over marine regions respectively. Our model-based analysis yields average enhancement ratios ΔO3/ΔCO of 0.12 ppbv/ppbv and a total O3 production of about 3.5 Tg from South Asia during the spring season. The findings demonstrate that the springtime fire emissions in South Asia have a noticeable impact on the O3 in this region.
Jiang, Z., J. R. Worden, D. B. A. Jones, J.-T. Lin, W. W. Verstraeten, and D. K. Henze (2015a), Constraints on Asian ozone using Aura TES, OMI and Terra MOPITT, Atmos. Chem. Phys., 15(1), 99–112, doi:10.5194/acp-15-99-2015.
Rapid industrialization in Asia in the last two decades has resulted in a significant increase in Asian ozone (O-3/precursor emissions with likely a corresponding increase in the export of O-3 and its precursors. However, the relationship between this increasing O-3, the chemical environment, O-3 production efficiency, and the partitioning between anthropogenic and natural precursors is unclear. In this work, we use satellite measurements of O-3, CO and NO2 from TES (Tropospheric Emission Spectrometer), MO-PITT (Measurement of Pollution In The Troposphere) and OMI (Ozone Monitoring Instrument) to quantify O-3 precursor emissions for 2006 and their impact on free tropospheric O-3 over northeastern Asia, where pollution is typically exported globally due to strong westerlies. Using the GEOS-Chem (Goddard Earth Observing System Chemistry) global chemical transport model, we test the modeled seasonal and interannual variation of O-3 based on prior and updated O-3 precursor emissions where the updated emissions of CO and NOx are based on satellite measurements of CO and NO2. We show that the observed TES O-3 variability and amount are consistent with the model for these updated emissions. However, there is little difference in the modeled ozone between the updated and prior emissions. For example, for the 2006 June time period, the prior and posterior NOx emissions were 14% different over China but the modeled ozone in the free troposphere was only 2.5% different. Using the ad-joint of GEOS-Chem we partition the relative contributions of natural and anthropogenic sources to free troposphere O-3 in this region. We find that the influence of lightning NOx in the summer is comparable to the contribution from surface emissions but smaller for other seasons. China is the primary contributor of anthropogenic CO, emissions and their export during the summer. While the posterior CO emissions improved the comparison between model and TES by 32%, on average, this change also had only a small effect on the free tropospheric ozone. Our results show that the influence of India and southeastern Asia emissions on O-3 pollution export to the northwestern Pacific is sizeable, comparable with Chinese emissions in winter, about 50% of Chinese emissions in spring and fall, and approximately 20% of the emissions in the summer.
Jiang, Z., D. B. A. Jones, J. Worden, H. M. Worden, D. K. Henze, and Y. X. Wang (2015b), Regional data assimilation of multi-spectral MOPITT observations of CO over North America, Atmos. Chem. Phys., 15(12), 6801–6814, doi:10.5194/acp-15-6801-2015.
Chemical transport models (CTMs) driven with high-resolution meteorological fields can better resolve small-scale processes, such as frontal lifting or deep convection, and thus improve the simulation and emission estimates of tropospheric trace gases. In this work, we explore the use of the GEOS-Chem four-dimensional variational (4D-Var) data assimilation system with the nested high-resolution version of the model (0.5A degrees x 0.67A degrees) to quantify North American CO emissions during the period of June 2004-May 2005. With optimized lateral boundary conditions, regional inversion analyses can reduce the sensitivity of the CO source estimates to errors in long-range transport and in the distributions of the hydroxyl radical (OH), the main sink for CO. To further limit the potential impact of discrepancies in chemical aging of air in the free troposphere, associated with errors in OH, we use surface-level multispectral MOPITT (Measurement of Pollution in The Troposphere) CO retrievals, which have greater sensitivity to CO near the surface and reduced sensitivity in the free troposphere, compared to previous versions of the retrievals. We estimate that the annual total anthropogenic CO emission from the contiguous US 48 states was 97 Tg CO, a 14 % increase from the 85 Tg CO in the a priori. This increase is mainly due to enhanced emissions around the Great Lakes region and along the west coast, relative to the a priori. Sensitivity analyses using different OH fields and lateral boundary conditions suggest a possible error, associated with local North American OH distribution, in these emission estimates of 20 % during summer 2004, when the CO lifetime is short. This 20 % OH-related error is 50 % smaller than the OH-related error previously estimated for North American CO emissions using a global inversion analysis. We believe that reducing this OH-related error further will require integrating additional observations to provide a strong constraint on the CO distribution across the domain. Despite these limitations, our results show the potential advantages of combining high-resolution regional inversion analyses with global analyses to better quantify regional CO source estimates.
Jiang, Z., D. B. A. Jones, H. M. Worden, and D. K. Henze (2015c), Sensitivity of top-down CO source estimates to the modeled vertical structure in atmospheric CO, Atmos. Chem. Phys., 15(3), 1521–1537, doi:10.5194/acp-15-1521-2015.
We assessed the sensitivity of regional CO source estimates to the modeled vertical CO distribution by assimilating multi-spectral MOPITT (Measurements of Pollution In The Troposphere) V5J CO retrievals with the GEOS-Chem model. We compared the source estimates obtained by assimilating the CO profiles and the surface layer retrievals from June 2004 to May 2005. Because the surface layer retrievals are less sensitive to CO in the free troposphere, it is expected that they should provide constraints in the CO source estimates that are less sensitive to the vertical structure of CO in the free troposphere. The inferred source estimates all suggest a reduction in CO emissions in the tropics and subtropics, and an increase in the extratropics over the a priori estimates. The tropical decreases were particularly pronounced for regions where the biogenic source of CO was dominant, suggesting an overestimate of the a priori isoprene source of CO in the model. We found that the differences between the regional source estimates inferred from the profile and surface layer retrievals for 2004–2005 were small, generally less than 10% for the main continental regions, except for estimates for southern Asia, North America, and Europe. Because of discrepancies in convective transport in the model, the CO source estimates for India and southeastern Asia inferred from the CO profiles were significantly higher than those estimated from the surface layer retrievals during June–August 2004. On the other hand, the profile inversion underestimated the CO emissions from North America and Europe compared to the assimilation of the surface layer retrievals. We showed that vertical transport of air from the North American and European boundary layers is slower than from other continental regions, and thus air in the free troposphere from North America and Europe in the model is more chemically aged, which could explain the discrepancy between the source estimates inferred from the profile and surface layer retrievals. We also examined the impact of the OH distribution on the source estimates and found that the discrepancies between the source estimates obtained with two OH fields were larger when using the profile data, which is consistent with greater sensitivity to the more chemically aged air in the free troposphere. Our findings indicate that regional CO source estimates are sensitive to the vertical CO structure. They suggest that diagnostics to assess the age of air from the continental source regions should help interpret the results from CO source inversions. Our results also suggest that assimilating a broader range of composition measurements to provide better constraint on tropospheric OH and the biogenic sources of CO is essential for reliable quantification of the regional CO budget.
Mandal, T. K., S. K. Peshin, C. Sharma, P. K. Gupta, R. Raj, and S. K. Sharma (2015), Study of surface ozone at Port Blair, India, a remote marine station in the Bay of Bengal, J. Atmos. Sol.-Terr. Phys., 129, 142–152, doi:10.1016/j.jastp.2015.04.010.
This paper presents seasonal variation of surface ozone monitored continuously at site of the meteorological observatory at Port Blair, a maritime site of the Bay of Bengal for the period of August, 2005-March, 2007. Present observation depicts the characteristics of surface ozone at the remote marine site and the long range transport of pollutants from three different sides i.e., Indian Subcontinent, South East Asia and Indian Ocean. Very high ozone mixing ratio (similar to 70-80 ppbv) is occasionally observed during March and November at this site. A campaign mode of observation of trace gases (surface ozone, CO, NOR, CO2), aerosol concentration and its size, UV radiation at Port Blair was made to understand the role of transport on pollutants during March 16-26, 2002. During this period of observation, a near zero surface ozone of different time scales (few hours) has been observed several times during the period of midnight to early morning. Simultaneously NOx (NO+NO2) (similar to 40 ppbv) and carbon monoxide was observed very high (300-600 ppbv) during this period. Source of this high pollutant are not expected at this remote marine sites although wind patterns, 7-days isentropic back Trajectory analysis and MATCH Model output suggest that polluted air mass has come from eastern side of Indian subcontinent. (C) 2015 Elsevier Ltd. All rights reserved.
Marey, H. S., Z. Hashisho, L. Fu, and J. Gille (2015), Spatial and temporal variation in CO over Alberta using measurements from satellites, aircraft, and ground stations, Atmos. Chem. Phys., 15(7), 3893–3908, doi:10.5194/acp-15-3893-2015.
Alberta is Canada’s largest oil producer, and its oil sands deposits comprise 30% of the world’s oil reserves. The process of bitumen extraction and upgrading releases trace gases and aerosols to the atmosphere. In this study we present satellite-based analysis to explore, for the first time, various contributing factors that affect tropospheric carbon monoxide (CO) levels over Alberta. The multispectral product that uses both near-infrared (NIR) and the thermal-infrared (TIR) radiances for CO retrieval from the Measurements of Pollution in the Troposphere (MOPITT) is examined for the 12-year period from 2002 to 2013. The Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomaly product from 2001 to 2013 is employed to investigate the seasonal and temporal variations in forest fires. Additionally, in situ CO measurements at industrial and urban sites are compared to satellite data. Furthermore, the available MOZAIC/IAGOS (Measurement of Ozone, Water Vapor, Carbon Monoxide, Nitrogen Oxide by Airbus In-Service Aircraft/In service Aircraft for Global Observing System) aircraft CO profiles (April 2009-December 2011) are used to validate MOPITT CO data. The climatological time curtain plot and spatial maps for CO over northern Alberta indicate the signatures of transported CO for two distinct biomass burning seasons: summer and spring. Distinct seasonal patterns of CO at the urban sites (Edmonton and Calgary) point to the strong influence of traffic. Meteorological parameters play an important role in the CO spatial distribution at various pressure levels. Northern Alberta shows a stronger upward lifting motion which leads to larger CO total column values, while the poor dispersion in central and southern Alberta exacerbates the surface CO pollution. Interannual variations in satellite data depict a slightly decreasing trend for both regions, while the decline trend is more evident from ground observations, especially at the urban sites. MOPITT CO vertical averages and MOZAIC/IAGOS aircraft profiles were in good agreement within the standard deviations at all pressure levels. There is consistency between the time evolution of high-CO episodes monitored by satellite and ground measurements and the fire frequency peak time, which implies that biomass burning has affected the tropospheric CO distribution in northern Alberta. These findings have further demonstrated the potential use of the MOPITT V5 multispectral (NIR + TIR) product for assessing a complicated surface process.
Miyazaki, K., H. J. Eskes, and K. Sudo (2015), A tropospheric chemistry reanalysis for the years 2005-2012 based on an assimilation of OMI, MLS, TES, and MOPITT satellite data, Atmos. Chem. Phys., 15(14), 8315–8348, doi:10.5194/acp-15-8315-2015.
We present the results from an 8-year tropospheric chemistry reanalysis for the period 2005-2012 obtained by assimilating multiple data sets from the OMI, MLS, TES, and MOPITT satellite instruments. The reanalysis calculation was conducted using a global chemical transport model and an ensemble Kalman filter technique that simultaneously optimises the chemical concentrations of various species and emissions of several precursors. The optimisation of both the concentration and the emission fields is an efficient method to correct the entire tropospheric profile and its year-to-year variations, and to adjust various tracers chemically linked to the species assimilated. Comparisons against independent aircraft, satellite, and ozonesonde observations demonstrate the quality of the analysed O-3, NO2, and CO concentrations on regional and global scales and for both seasonal and year-to-year variations from the lower troposphere to the lower stratosphere. The data assimilation statistics imply persistent reduction of model error and improved representation of emission variability, but they also show that discontinuities in the availability of the measurements lead to a degradation of the reanalysis. The decrease in the number of assimilated measurements increased the ozonesonde-minus-analysis difference after 2010 and caused spurious variations in the estimated emissions. The Northern/Southern Hemisphere OH ratio was modified considerably due to the multiple-species assimilation and became closer to an observational estimate, which played an important role in propagating observational information among various chemical fields and affected the emission estimates. The consistent concentration and emission products provide unique information on year-to-year variations in the atmospheric environment.
Rakitin, V. S. S. (2015), Results of comparison of satellite and ground-based spectroscopic CO, CH 4, and CO 2 columns measurements, Optika atmosfery i okeana, 28(9), 816–824, doi:10.15372/AOO20150907.
A significant amount of satellite and ground data of the CO, CO 2, CH 4 total content in the atmosphere in 2010-2013 was collected, organized and analyzed. Transition relations between satellite and ground-based data on the content of impurities investigated in different measuring points (stations NDACC/GAW, as well as the OIAP RAS stations) with different spatial and temporal resolutions has been obtained. High correlation of diurnal satellite CO contents, products of AIRS v6 ( R 2 = 0.48-0.96), IASI MetOp-A ( R 2 = 0.25-0.86) and MOPITT v6 Joint ( R 2 = 0.30-0.83), averaging 1° x 1°, with the ground data of solar spectrometers was established for background conditions. In the case of high pollution of the mixing layer, a significant underestimation of CO total content (from 1.7 to 4.7 times, depending on the sensor, and the spatial point of observation) was seen. Representative transition relations and correlation coefficients ( R 2 ≥ 0.5) between the average daily data on CH 4 and ground data diffraction spectrometers IAP RAS and Fourier spectrometers of GAW stations were obtained only for sensor AIRS. The best correlation with ground data on CO 2 ( R 2 = 0.25 for diurnal values, averaging 1° x 1°) was obtained for the sensor IASI. Diurnal CH 4 total contents of sensor IASI MetOp-A poorly correlated with ground-based data as well as AIRS data.
Surendran, D. E., S. D. Ghude, G. Beig, L. K. Emmons, C. Jena, R. Kumar, G. G. Pfister, and D. M. Chate (2015), Air quality simulation over South Asia using Hemispheric Transport of Air Pollution version-2 (HTAP-v2) emission inventory and Model for Ozone and Related chemical Tracers (MOZART-4), Atmos. Environ., 122, 357–372, doi:10.1016/j.atmosenv.2015.08.023.
This study presents the distribution of tropospheric ozone and related species for South Asia using the Model for Ozone and Related chemical Tracers (MOZART-4) and Hemispheric Transport of Air Pollution version-2 (HTAP-v2) emission inventory. The model present-day simulated ozone (O-3), carbon monoxide (CO) and nitrogen dioxide (NO2) are evaluated against surface-based, balloon-borne and satellite-based (MOPITT and OMI) observations. The model systematically overestimates surface O-3 mixing ratios (range of mean bias about: 1-30 ppbv) at different ground-based measurement sites in India. Comparison between simulated and observed vertical profiles of ozone shows a positive bias from the surface up to 600 hPa and a negative bias above 600 hPa. The simulated seasonal variation in surface CO mixing ratio is consistent with the surface observations, but has a negative bias of about 50-200 ppb which can be attributed to a large part to the coarse model resolution. In contrast to the surface evaluation, the model shows a positive bias of about 15-20 x 10(17) molecules/cm(2) over South Asia when compared to satellite derived CO columns from the MOPITT instrument. The model also overestimates OMI retrieved tropospheric column NO2 abundance by about 100-250 x 10(13) molecules/cm(2). A response to 20% reduction in all anthropogenic emissions over South Asia shows a decrease in the anuual mean O-3 mixing ratios by about 3-12 ppb, CO by about 10-80 ppb and NOx by about 3-6 ppb at the surface level. During summer monsoon, O-3 mixing ratios at 200 hPa show a decrease of about 6-12 ppb over South Asia and about 1-4 ppb over the remote northern hemispheric western Pacific region. (C) 2015 Elsevier Ltd. All rights reserved.
de Vries, M. J. M. P., S. Beirle, C. Hoermann, J. W. Kaiser, P. Stammes, L. G. Tilstra, O. N. E. Tuinder, and T. Wagner (2015), A global aerosol classification algorithm incorporating multiple satellite data sets of aerosol and trace gas abundances, Atmos. Chem. Phys., 15(18), 10597–10618, doi:10.5194/acp-15-10597-2015.
Detecting the optical properties of aerosols using passive satellite-borne measurements alone is a difficult task due to the broadband effect of aerosols on the measured spectra and the influences of surface and cloud reflection. We present another approach to determine aerosol type, namely by studying the relationship of aerosol optical depth (AOD) with trace gas abundance, aerosol absorption, and mean aerosol size. Our new Global Aerosol Classification Algorithm, GACA, examines relationships between aerosol properties (AOD and extinction ngstrom exponent from the Moderate Resolution Imaging Spectroradiometer (MODIS), UV Aerosol Index from the second Global Ozone Monitoring Experiment, GOME-2) and trace gas column densities (NO2, HCHO, SO2 from GOME-2, and CO from MOPITT, the Measurements of Pollution in the Troposphere instrument) on a monthly mean basis. First, aerosol types are separated based on size (ngstrom exponent) and absorption (UV Aerosol Index), then the dominating sources are identified based on mean trace gas columns and their correlation with AOD. In this way, global maps of dominant aerosol type and main source type are constructed for each season and compared with maps of aerosol composition from the global MACC (Monitoring Atmospheric Composition and Climate) model. Although GACA cannot correctly characterize transported or mixed aerosols, GACA and MACC show good agreement regarding the global seasonal cycle, particularly for urban/industrial aerosols. The seasonal cycles of both aerosol type and source are also studied in more detail for selected 5A degrees x 5A degrees regions. Again, good agreement between GACA and MACC is found for all regions, but some systematic differences become apparent: the variability of aerosol composition (yearly and/or seasonal) is often not well captured by MACC, the amount of mineral dust outside of the dust belt appears to be overestimated, and the abundance of secondary organic aerosols is underestimated in comparison with GACA. Whereas the presented study is of exploratory nature, we show that the developed algorithm is well suited to evaluate climate and atmospheric composition models by including aerosol type and source obtained from measurements into the comparison, instead of focusing on a single parameter, e.g., AOD. The approach could be adapted to constrain the mix of aerosol types during the process of a combined data assimilation of aerosol and trace gas observations.
Wang, K., K. Yahya, Y. Zhang, C. Hogrefe, G. Pouliot, C. Knote, A. Hodzic, R. San Jose, J. L. Perez, P. Jiménez-Guerrero, R. Baro, P. Makar, and R. Bennartz (2015a), A multi-model assessment for the 2006 and 2010 simulations under the Air Quality Model Evaluation International Initiative (AQMEII) Phase 2 over North America: Part II. Evaluation of column variable predictions using satellite data, Atmospheric Environment, doi:10.1016/j.atmosenv.2014.07.044. [online] Available from: http://www.sciencedirect.com/science/article/pii/S1352231014005743 .
Within the context of the Air Quality Model Evaluation International Initiative Phase 2 (AQMEII2) project, this part II paper performs a multi-model assessment of major column abundances of gases, radiation, aerosol, and cloud variables for 2006 and 2010 simulations with three online-coupled air quality models over the North America using available satellite data. It also provides the first comparative assessment of the capabilities of the current generation of online-coupled models in simulating column variables. Despite the use of different model configurations and meteorological initial and boundary conditions, most simulations show comparable model performance for many variables. The evaluation results show an excellent agreement between all simulations and satellite-derived radiation variables including downward surface solar radiation, longwave radiation, and top-of-atmospheric outgoing longwave radiation, as well as precipitable water vapor with domain-average normalized mean biases (NMBs) of typically less than 5% and correlation coefficient (R) typically more than 0.9. Most simulations perform well for column-integrated abundance of CO with domain-average NMBs of −9.4% to −2.2% in 2006 and −12.1% to 4.6% in 2010 and from reasonably well to fair for column NO2, HCHO, and SO2, with domain-average NMBs of −37.7% to 2.1%, −27.3% to 59.2%, and 16.1% to 114.2% in 2006, respectively, and, 12.9% to 102.1%, −25.0% to 87.6%, −65.2% to 7.4% in 2010, respectively. R values are high for CO and NO2 typically between 0.85 and 0.9 (i.e., R2 of 0.7–0.8). Tropospheric ozone residuals are overpredicted by all simulations due to overestimates of ozone profiles from boundary conditions. Model performance for cloud-related variables is mixed and generally worse compared to gases and radiation variables. Cloud fraction (CF) is well reproduced by most simulations. Other aerosol/cloud related variables such as aerosol optical depth (AOD), cloud optical thickness, cloud liquid water path, cloud condensation nuclei, and cloud droplet number concentration (CDNC) are moderately to largely underpredicted by most simulations, due to underpredictions of aerosol loadings and also indicating high uncertainties associated with the current model treatments of aerosol–cloud interactions and the need for further model development. Negative correlations are found for AOD for most simulations due to large negative biases over the western part of the domain. Inter-model discrepancies also exist for a few variables such as column abundances of HCHO and SO2 and CDNC due likely to different chemical mechanisms, biogenic emissions, and treatments of aerosol indirect effects. Most simulations can also capture the inter-annual trend observed by satellites between 2006 and 2010 for several variables such as column abundance of NO2, AOD, CF, and CDNC. Results shown in this work provide the important benchmark for future online-couple air quality model development.
Wang, K., K. Yahya, Y. Zhang, C. Hogrefe, G. Pouliot, C. Knote, A. Hodzic, R. San Jose, J. L. Perez, P. Jiménez-Guerrero, R. Baro, P. Makar, and R. Bennartz (2015b), A multi-model assessment for the 2006 and 2010 simulations under the Air Quality Model Evaluation International Initiative (AQMEII) Phase 2 over North America: Part II. Evaluation of column variable predictions using satellite data, Atmospheric Environment, 115, 587–603, doi:10.1016/j.atmosenv.2014.07.044.
Within the context of the Air Quality Model Evaluation International Initiative Phase 2 (AQMEII2) project, this part II paper performs a multi-model assessment of major column abundances of gases, radiation, aerosol, and cloud variables for 2006 and 2010 simulations with three online-coupled air quality models over the North America using available satellite data. It also provides the first comparative assessment of the capabilities of the current generation of online-coupled models in simulating column variables. Despite the use of different model configurations and meteorological initial and boundary conditions, most simulations show comparable model performance for many variables. The evaluation results show an excellent agreement between all simulations and satellite-derived radiation variables including downward surface solar radiation, longwave radiation, and top-of-atmospheric outgoing longwave radiation, as well as precipitable water vapor with domain-average normalized mean biases (NMBs) of typically less than 5% and correlation coefficient (R) typically more than 0.9. Most simulations perform well for column-integrated abundance of CO with domain-average NMBs of −9.4% to −2.2% in 2006 and −12.1% to 4.6% in 2010 and from reasonably well to fair for column NO2, HCHO, and SO2, with domain-average NMBs of −37.7% to 2.1%, −27.3% to 59.2%, and 16.1% to 114.2% in 2006, respectively, and, 12.9% to 102.1%, −25.0% to 87.6%, −65.2% to 7.4% in 2010, respectively. R values are high for CO and NO2 typically between 0.85 and 0.9 (i.e., R2 of 0.7–0.8). Tropospheric ozone residuals are overpredicted by all simulations due to overestimates of ozone profiles from boundary conditions. Model performance for cloud-related variables is mixed and generally worse compared to gases and radiation variables. Cloud fraction (CF) is well reproduced by most simulations. Other aerosol/cloud related variables such as aerosol optical depth (AOD), cloud optical thickness, cloud liquid water path, cloud condensation nuclei, and cloud droplet number concentration (CDNC) are moderately to largely underpredicted by most simulations, due to underpredictions of aerosol loadings and also indicating high uncertainties associated with the current model treatments of aerosol–cloud interactions and the need for further model development. Negative correlations are found for AOD for most simulations due to large negative biases over the western part of the domain. Inter-model discrepancies also exist for a few variables such as column abundances of HCHO and SO2 and CDNC due likely to different chemical mechanisms, biogenic emissions, and treatments of aerosol indirect effects. Most simulations can also capture the inter-annual trend observed by satellites between 2006 and 2010 for several variables such as column abundance of NO2, AOD, CF, and CDNC. Results shown in this work provide the important benchmark for future online-couple air quality model development.
Whaley, C. H., K. Strong, D. B. A. Jones, T. W. Walker, Z. Jiang, D. K. Henze, M. A. Cooke, C. A. McLinden, R. L. Mittermeier, M. Pommier, and P. F. Fogal (2015), Toronto area ozone: Long-term measurements and modeled sources of poor air quality events, J. Geophys. Res. Atmos., 120(21), 2014JD022984, doi:10.1002/2014JD022984.
The University of Toronto Atmospheric Observatory and Environment Canada’s Centre for Atmospheric Research Experiments each has over a decade of ground-based Fourier transform infrared (FTIR) spectroscopy measurements in southern Ontario. We present the Toronto area FTIR time series from 2002 to 2013 of two tropospheric trace gases—ozone and carbon monoxide—along with surface in situ measurements taken by government monitoring programs. We interpret their variability with the GEOS-Chem chemical transport model and determine the atmospheric conditions that cause pollution events in the time series. Our analysis includes a regionally tagged O3 model of the 2004–2007 time period, which quantifies the geographical contributions to Toronto area O3. The important emission types for 15 pollution events are then determined with a high-resolution adjoint model. Toronto O3, during pollution events, is most sensitive to southern Ontario and U.S. fossil fuel NOx emissions and natural isoprene emissions. The sources of Toronto pollution events are found to be highly variable, and this is demonstrated in four case studies representing local, short-, middle-, and long-range transport scenarios. This suggests that continental-scale emission reductions could improve air quality in the Toronto region. We also find that abnormally high temperatures and high-pressure systems are common to all pollution events studied, suggesting that climate change may impact Toronto O3. Finally, we quantitatively compare the sensitivity of the surface and column measurements to anthropogenic NOx emissions and show that they are remarkably similar. This work thus demonstrates the usefulness of FTIR measurements in an urban area to assess air quality.
Yahya, K., J. He, and Y. Zhang (2015), Multiyear applications of WRF/Chem over continental U.S.: Model evaluation, variation trend, and impacts of boundary conditions, J. Geophys. Res. Atmos., 120(24), 2015JD023819, doi:10.1002/2015JD023819.
Multiyear applications of an online-coupled meteorology-chemistry model allow an assessment of the variation trends in simulated meteorology, air quality, and their interactions to changes in emissions and meteorology, as well as the impacts of initial and boundary conditions (ICONs/BCONs) on simulated aerosol-cloud-radiation interactions over a period of time. In this work, the Weather Research and Forecasting model with Chemistry version 3.4.1 (WRF/Chem v. 3.4.1) with the 2005 Carbon Bond mechanism coupled with the Volatility Basis Set module for secondary organic aerosol formation (WRF/Chem-CB05-VBS) is applied for multiple years (2001, 2006, and 2010) over continental U.S. This work also examines the changes in simulated air quality and meteorology due to changes in emissions and meteorology and the model’s capability in reproducing the observed variation trends in species concentrations from 2001 to 2010. In addition, the impacts of the chemical ICONs/BCONs on model predictions are analyzed. ICONs/BCONs are downscaled from two global models, the modified Community Earth System Model/Community Atmosphere model version 5.1 (CESM/CAM v5.1) and the Monitoring Atmospheric Composition and Climate model (MACC). The evaluation of WRF/Chem-CB05-VBS simulations with the CESM ICONs/BCONs for 2001, 2006, and 2010 shows that temperature at 2 m (T2) is underpredicted for all three years likely due to inaccuracies in soil moisture and soil temperature, resulting in biases in surface relative humidity, wind speed, and precipitation. With the exception of cloud fraction, other aerosol-cloud variables including aerosol optical depth, cloud droplet number concentration, and cloud optical thickness are underpredicted for all three years, resulting in overpredictions of radiation variables. The model performs well for O3 and particulate matter with diameter less than or equal to 2.5 (PM2.5) for all three years comparable to other studies from literature. The model is able to reproduce observed annual average trends in O3 and PM2.5 concentrations from 2001 to 2006 and from 2006 to 2010 but is less skillful in simulating their observed seasonal trends. The 2006 and 2010 results using CESM and MACC ICONs/BCONs are compared to analyze the impact of ICONs/BCONs on model performance and their feedbacks to aerosol, clouds, and radiation. Comparing to the simulations with MACC ICONs/BCONs, the simulations with the CESM ICONs/BCONs improve the performance of O3 mixing ratios (e.g., the normalized mean bias for maximum 8 h O3 is reduced from −17% to −1% in 2010), PM2.5 in 2010, and sulfate in 2006 (despite a slightly larger normalized mean bias for PM2.5 in 2006). The impacts of different ICONs/BCONs on simulated aerosol-cloud-radiation variables are not negligible, with larger impacts in 2006 compared to 2010.
Yin, Y., F. Chevallier, P. Ciais, G. Broquet, A. Fortems-Cheiney, I. Pison, and M. Saunois (2015), Decadal trends in global CO emissions as seen by MOPITT, Atmos. Chem. Phys., 15(23), 13433–13451, doi:10.5194/acp-15-13433-2015.
Negative trends of carbon monoxide (CO) concentrations are observed in the recent decade by both surface measurements and satellite retrievals over many regions of the globe, but they are not well explained by current emission inventories. Here, we analyse the observed CO concentration decline with an atmospheric inversion that simultaneously optimizes the two main CO sources (surface emissions and atmospheric hydrocarbon oxidations) and the main CO sink (atmospheric hydroxyl radical OH oxidation). Satellite CO column retrievals from Measurements of Pollution in the Troposphere (MOPITT), version 6, and surface observations of methane and methyl chloroform mole fractions are assimilated jointly for the period covering 2002-2011. Compared to the model simulation prescribed with prior emission inventories, trends in the optimized CO concentrations show better agreement with that of independent surface in situ measurements. At the global scale, the atmospheric inversion primarily interprets the CO concentration decline as a decrease in the CO emissions (-2.3% yr(-1)), more than twice the negative trend estimated by the prior emission inventories (-1.0% yr(-1)). The spatial distribution of the inferred decrease in CO emissions indicates contributions from western Europe (-4.0% yr(-1)), the United States (-4.6% yr(-1)) and East Asia (-1.2% yr(-1)), where anthropogenic fuel combustion generally dominates the overall CO emissions, and also from Australia (-5.3% yr(-1)), the Indo-China Peninsula (-5.6% yr(-1)), Indonesia (-6.7% yr(-1)), and South America (-3% yr(-1)), where CO emissions are mostly due to biomass burning. In contradiction with the bottom-up inventories that report an increase of 2% yr(-1) over China during the study period, a significant emission decrease of 1.1% yr(-1) is inferred by the inversion. A large decrease in CO emission factors due to technology improvements would outweigh the increase in carbon fuel combustions and may explain this decrease. Independent satellite formaldehyde (CH2O) column retrievals confirm the absence of large-scale trends in the atmospheric source of CO. However, it should be noted that the CH2O retrievals are not assimilated and OH concentrations are optimized at a very large scale in this study.
Zeng, G., J. E. Williams, J. A. Fisher, L. K. Emmons, N. B. Jones, O. Morgenstern, J. Robinson, D. Smale, C. Paton-Walsh, and D. W. T. Griffith (2015), Multi-model simulation of CO and HCHO in the Southern Hemisphere: comparison with observations and impact of biogenic emissions, Atmospheric Chemistry and Physics, 15(13), 7217–7245, doi:http://dx.doi.org/10.5194/acp-15-7217-2015.
We investigate the impact of biogenic emissions on carbon monoxide (CO) and formaldehyde (HCHO) in the Southern Hemisphere (SH), with simulations using two different biogenic emission inventories for isoprene and monoterpenes. Results from four atmospheric chemistry models are compared to continuous long-term ground-based CO and HCHO column measurements at the SH Network for the Detection of Atmospheric Composition Change (NDACC) sites, the satellite measurement of tropospheric CO columns from the Measurement of Pollution in the Troposphere (MOPITT), and in situ surface CO measurements from across the SH, representing a subset of the National Oceanic and Atmospheric Administration’s Global Monitoring Division (NOAA GMD) network. Simulated mean model CO using the Model of Emissions of Gases and Aerosols from Nature (v2.1) computed in the frame work of the Land Community Model (CLM-MEGANv2.1) inventory is in better agreement with both column and surface observations than simulations adopting the emission inventory generated from the LPJ-GUESS dynamical vegetation model framework, which markedly underestimate measured column and surface CO at most sites. Differences in biogenic emissions cause large differences in CO in the source regions which propagate to the remote SH. Significant inter-model differences exist in modelled column and surface CO, and secondary production of CO dominates these inter-model differences, due mainly to differences in the models’ oxidation schemes for volatile organic compounds, predominantly isoprene oxidation. While biogenic emissions are a significant factor in modelling SH CO, inter-model differences pose an additional challenge to constrain these emissions. Corresponding comparisons of HCHO columns at two SH mid-latitude sites reveal that all models significantly underestimate the observed values by approximately a factor of 2. There is a much smaller impact on HCHO of the significantly different biogenic emissions in remote regions, compared to the source regions. Decreased biogenic emissions cause decreased CO export to remote regions, which leads to increased OH; this in turn results in increased HCHO production through methane oxidation. In agreement with earlier studies, we corroborate that significant HCHO sources are likely missing in the models in the remote SH.
Zhang, Y., X. Zhang, K. Wang, J. He, L. R. Leung, J. Fan, and A. Nenes (2015), Incorporating an advanced aerosol activation parameterization into WRF-CAM5: Model evaluation and parameterization intercomparison, J. Geophys. Res. Atmos., 120(14), 2014JD023051, doi:10.1002/2014JD023051.
Aerosol activation into cloud droplets is an important process that governs aerosol indirect effects. The advanced treatment of aerosol activation by Fountoukis and Nenes (2005) and its recent updates, collectively called the FN series, have been incorporated into a newly developed regional coupled climate-air quality model based on the Weather Research and Forecasting model with the physics package of the Community Atmosphere Model version 5 (WRF-CAM5) to simulate aerosol-cloud interactions in both resolved and convective clouds. The model is applied to East Asia for two full years of 2005 and 2010. A comprehensive model evaluation is performed for model predictions of meteorological, radiative, and cloud variables, chemical concentrations, and column mass abundances against satellite data and surface observations from air quality monitoring sites across East Asia. The model performs overall well for major meteorological variables including near-surface temperature, specific humidity, wind speed, precipitation, cloud fraction, precipitable water, downward shortwave and longwave radiation, and column mass abundances of CO, SO2, NO2, HCHO, and O3 in terms of both magnitudes and spatial distributions. Larger biases exist in the predictions of surface concentrations of CO and NOx at all sites and SO2, O3, PM2.5, and PM10 concentrations at some sites, aerosol optical depth, cloud condensation nuclei over ocean, cloud droplet number concentration (CDNC), cloud liquid and ice water path, and cloud optical thickness. Compared with the default Abdul-Razzack Ghan (2000) parameterization, simulations with the FN series produce ~107–113% higher CDNC, with half of the difference attributable to the higher aerosol activation fraction by the FN series and the remaining half due to feedbacks in subsequent cloud microphysical processes. With the higher CDNC, the FN series are more skillful in simulating cloud water path, cloud optical thickness, downward shortwave radiation, shortwave cloud forcing, and precipitation. The model evaluation identifies several areas of improvements including emissions and their vertical allocation as well as model formulations such as aerosol formation, cloud droplet nucleation, and ice nucleation.

2014

Amnuaylojaroen, T., M. C. Barth, L. K. Emmons, G. R. Carmichael, J. Kreasuwun, S. Prasitwattanaseree, and S. Chantara (2014), Effect of different emission inventories on modeled ozone and carbon monoxide in Southeast Asia, Atmospheric Chemistry and Physics, 14(23), 12983–13012, doi:10.5194/acp-14-12983-2014.
In order to improve our understanding of air quality in Southeast Asia, the anthropogenic emissions inventory must be well represented. In this work, we apply different anthropogenic emission inventories in the Weather Research and Forecasting Model with Chemistry (WRF-Chem) version 3.3 using Model for Ozone and Related Chemical Tracers (MOZART) gas-phase chemistry and Global Ozone Chemistry Aerosol Radiation and Transport (GOCART) aerosols to examine the differences in predicted carbon monoxide (CO) and ozone (O3) surface mixing ratios for Southeast Asia in March and December 2008. The anthropogenic emission inventories include the Reanalysis of the TROpospheric chemical composition (RETRO), the Intercontinental Chemical Transport Experiment-Phase B (INTEX-B), the MACCity emissions (adapted from the Monitoring Atmospheric Composition and Climate and megacity Zoom for the Environment projects), the Southeast Asia Composition, Cloud, Climate Coupling Regional Study (SEAC4RS) emissions, and a combination of MACCity and SEAC4RS emissions. Biomass-burning emissions are from the Fire Inventory from the National Center for Atmospheric Research (NCAR) (FINNv1) model. WRF-Chem reasonably predicts the 2 m temperature, 10 m wind, and precipitation. In general, surface CO is underpredicted by WRF-Chem while surface O3 is overpredicted. The NO2 tropospheric column predicted by WRF-Chem has the same magnitude as observations, but tends to underpredict the NO2 column over the equatorial ocean and near Indonesia. Simulations using different anthropogenic emissions produce only a slight variability of O3 and CO mixing ratios, while biomass-burning emissions add more variability. The different anthropogenic emissions differ by up to 30 % in CO emissions, but O3 and CO mixing ratios averaged over the land areas of the model domain differ by ∼ 4.5 % and ∼ 8 %, respectively, among the simulations. Biomass-burning emissions create a substantial increase for both O3 and CO by ∼ 29 % and ∼ 16 %, respectively, when comparing the March biomass-burning period to the December period with low biomass-burning emissions. The simulations show that none of the anthropogenic emission inventories are better than the others for predicting O3 surface mixing ratios. However, the simulations with different anthropogenic emission inventories do differ in their predictions of CO surface mixing ratios producing variations of ∼ 30 % for March and 10–20 % for December at Thai surface monitoring sites.
Anderson, D. C., C. P. Loughner, G. Diskin, A. Weinheimer, T. P. Canty, R. J. Salawitch, H. M. Worden, A. Fried, T. Mikoviny, A. Wisthaler, and R. R. Dickerson (2014), Measured and modeled CO and NOy in DISCOVER-AQ: An evaluation of emissions and chemistry over the eastern US, Atmospheric Environment, 96, 78–87, doi:10.1016/j.atmosenv.2014.07.004.
Data collected during the 2011 DISCOVER-AQ field campaign in the Baltimore Washington region were used to evaluate CO and NOx emissions in the National Emissions Inventory (NEI). The average emissions ratio for the region was seen to be 11.2 ± 1.2 mol CO/mol NOx, 21% higher than that predicted by the NEI. Comparisons between in situ and remote observations and CMAQ model output show agreement in CO emissions of 15 ± 11% while NOx emissions are overestimated by 51–70% in Maryland. Satellite observations of CO by MOPITT show agreement with the Community Multiscale Air Quality (CMAQ) model within 3% over most of the eastern United States. CMAQ NOy mixing ratios were a factor of two higher than observations and result from a combination of errors in emissions and PAN and alkyl nitrate chemistry, as shown by comparison of three CMAQ model runs. Point source NOx emissions are monitored and agree with modeled emissions within 1% on a monthly basis. Because of this accuracy and the NEI assertion that approximately 3/4 of emissions in the Baltimore Washington region are from mobile sources, the MOVES model’s treatment of emissions from aging vehicles should be investigated; the NEI overestimate of NOx emissions could indicate that engines produce less NOx and catalytic converters degrade more slowly than assumed by MOVES2010. The recently released 2011 NEI has an even lower CO/NOx emissions ratio than the projection used in this study; it overestimates NOx emissions by an even larger margin. The implications of these findings for US air quality policy are that NOx concentrations near areas of heavy traffic are overestimated and ozone production rates in these locations are slower than models indicate. Results also indicate that ambient ozone concentrations will respond more efficiently to NOx emissions controls but additional sources may need to be targeted for reductions.
Boynard, A., C. Clerbaux, L. Clarisse, S. Safieddine, M. Pommier, M. Van Damme, S. Bauduin, C. Oudot, J. Hadji-Lazaro, D. Hurtmans, and P.-F. Coheur (2014), First simultaneous space measurements of atmospheric pollutants in the boundary layer from IASI: A case study in the North China Plain, Geophys. Res. Lett., 41(2), 645–651, doi:10.1002/2013GL058333.
In this paper we investigate a severe pollution episode that occurred in Beijing, Tianjin, and the Hebei province in January 2013. The episode was caused by the combination of anthropogenic emissions and a high-pressure system that trapped pollutants in the boundary layer. Using IASI (Infrared Atmospheric Sounding Interferometer) satellite measurements, high concentrations of key trace gases such as carbon monoxide (CO), sulfur dioxide (SO2), and ammonia (NH3) along with ammonium sulfate aerosol ((NH4)2SO4) are found. We show that IASI is able to detect boundary layer pollution in case of large negative thermal contrast combined with high levels of pollution. Our findings demonstrate that anthropogenic key pollutants, such as CO and SO2, can be monitored by IASI in the North China Plain during wintertime in support of air quality evaluation and management.
Castellanos, P., K. F. Boersma, and G. R. van der Werf (2014), Satellite observations indicate substantial spatiotemporal variability in biomass burning NOx emission factors for South America, Atmos. Chem. Phys., 14(8), 3929–3943, doi:10.5194/acp-14-3929-2014.
Biomass burning is an important contributor to global total emissions of NOx (NO+NO2). Generally bottom-up fire emissions models calculate NOx emissions by multiplying fuel consumption estimates with static biome-specific emission factors, defined in units of grams of NO per kilogram of dry matter consumed. Emission factors are a significant source of uncertainty in bottom-up fire emissions modeling because relatively few observations are available to characterize the large spatial and temporal variability of burning conditions. In this paper we use NO2 tropospheric column observations from the Ozone Monitoring Instrument (OMI) from the year 2005 over South America to calculate monthly NOx emission factors for four fire types: deforestation, savanna/grassland, woodland, and agricultural waste burning. In general, the spatial patterns in NOx emission factors calculated in this work are consistent with emission factors derived from in situ measurements from the region but are more variable than published biome-specific global average emission factors widely used in bottom-up fire emissions inventories such as the Global Fire Emissions Database (GFED). Satellite-based NOx emission factors also indicate substantial temporal variability in burning conditions. Overall, we found that deforestation fires have the lowest NOx emission factors, on average 30% lower than the emission factors used in GFED v3. Agricultural fire NOx emission factors were the highest, on average a factor of 1.8 higher than GFED v3 values. For savanna, woodland, and deforestation fires, early dry season NOx emission factors were a factor of ~1.5–2 higher than late dry season emission factors. A minimum in the NOx emission factor seasonal cycle for deforestation fires occurred in August, the time period of severe drought in South America in 2005, supporting the hypothesis that prolonged dry spells may lead to an increase in the contribution of smoldering combustion from large-diameter fuels, offsetting the higher combustion efficiency of dryer fine fuels. We evaluated the OMI-derived NOx emission factors with SCIAMACHY NO2 tropospheric column observations and found improved model performance in regions dominated by fire emissions.
Deeter, M. N., S. Martínez-Alonso, D. P. Edwards, L. K. Emmons, J. C. Gille, H. M. Worden, C. Sweeney, J. V. Pittman, B. C. Daube, and S. C. Wofsy (2014), The MOPITT Version 6 product: algorithm enhancements and validation, Atmos. Meas. Tech., 7(11), 3623–3632, doi:10.5194/amt-7-3623-2014.
The Measurements of Pollution in the Troposphere (MOPITT) Version 6 (V6) product for carbon monoxide (CO) incorporates several enhancements which will benefit many users of MOPITT data. V6 algorithm improvements are described in detail, and V6 validation results are presented. First, a geolocation bias related to the orientation of the MOPITT instrument relative to the TERRA platform was characterized and eliminated. Second, the variable a priori for CO concentrations for V6 is based on simulations performed with the chemical transport model Community Atmosphere Model with Chemistry (CAM-chem) for the years 2000–2009 instead of the model-derived climatology for 1997–2004 used for V5. Third, meteorological fields required for V6 retrieval processing are extracted from the MERRA (Modern-Era Retrospective Analysis For Research And Applications) reanalysis. Finally, a significant latitude-dependent retrieval bias in the upper troposphere in Version 5 products has been substantially reduced.
Ding, K., J. Liu, A. Ding, Q. Liu, T. L. Zhao, J. Shi, Y. Han, H. Wang, and F. Jiang (2014), Uplifting of carbon monoxide from biomass burning and anthropogenic  sources to the free troposphere in East Asia, Atmos. Chem. Phys. Discuss., 14(20), 28019–28077, doi:10.5194/acpd-14-28019-2014.
East Asia has experienced rapid development with increasing CO emission in the past decades. Therefore, uplifting CO from the boundary layer to the free troposphere in East Asia can have great implications on regional air quality. It can also influence global climate due to the longer lifetime of CO at higher altitudes. In this study, three cases of high CO episodes in East Asia from 2003 to 2005 are examined with spaceborne Measurements Of Pollution In The Troposphere (MOPITT) data, in combination with aircraft measurements from the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) program. High CO abundances of 300–550 ppbv were observed in MOZAIC data in the free troposphere during these episodes.  These are among the highest CO abundances documented at these altitudes.  Correspondingly, elevated CO was shown in MOPITT daytime data in the middle to upper troposphere in the 2003 case, mostly in the lower to middle troposphere in the 2004 case, and in the upper troposphere in the 2005 case.  Through analyses of the simulations from a chemical transport model GEOS-Chem and a trajectory dispersion model FLEXPART, we found different CO signatures in the elevated CO and distinct transport pathways and mechanisms for these cases. In the 2003 case, CO from large forest fires near Lake Baikal dominated the elevated CO, which had been rapidly transported upward by a~frontal system from the fire plumes. In the 2004 case, anthropogenic CO from the North China Plain experienced frontal lifting and mostly reached ~ 700 hPa near the East China Sea, while CO from biomass burning from Indochina experienced orographic lifting, leeside-trough induced convection, and frontal lifting through two separate transport pathways, leading to two distinct CO enhancements around 700 hPa and 300 hPa. In the 2005 case, high CO of ~ 300 ppbv, observed in the MOZAIC data around 350 hPa, originated from the anthropogenic source over the vicinity of the Sichuan basin and biomass burning from Indochina, after convection and strong frontal lifting. These cases show that topography affects vertical transport of CO in East Asia via different ways, including orographic uplifting over the Hengduan Mountains, assisting frontal lifting in the North China Plain, and facilitating convection in the Sichuan basin. In particular, topography-induced leeside troughs over Indochina lead to strong convection that assisted CO uplifting to the upper troposphere. This study shows that the new daytime MOPITT near-infrared (NIR) and thermal-infrared (TIR) data (version 5 or above) have enhanced vertical sensitivity and may help qualitative diagnosis of vertical transport processes in East Asia.
Duncan, B. N., A. I. Prados, L. N. Lamsal, Y. Liu, D. G. Streets, P. Gupta, E. Hilsenrath, R. A. Kahn, J. E. Nielsen, A. J. Beyersdorf, S. P. Burton, A. M. Fiore, J. Fishman, D. K. Henze, C. A. Hostetler, N. A. Krotkov, P. Lee, M. Lin, S. Pawson, G. Pfister, K. E. Pickering, R. B. Pierce, Y. Yoshida, and L. D. Ziemba (2014), Satellite data of atmospheric pollution for U.S. air quality applications: Examples of applications, summary of data end-user resources, answers to FAQs, and common mistakes to avoid, Atmospheric Environment, 94, 647–662, doi:10.1016/j.atmosenv.2014.05.061.
Satellite data of atmospheric pollutants are becoming more widely used in the decision-making and environmental management activities of public, private sector and non-profit organizations. They are employed for estimating emissions, tracking pollutant plumes, supporting air quality forecasting activities, providing evidence for “exceptional event” declarations, monitoring regional long-term trends, and evaluating air quality model output. However, many air quality managers are not taking full advantage of the data for these applications nor has the full potential of satellite data for air quality applications been realized. A key barrier is the inherent difficulties associated with accessing, processing, and properly interpreting observational data. A degree of technical skill is required on the part of the data end-user, which is often problematic for air quality agencies with limited resources. Therefore, we 1) review the primary uses of satellite data for air quality applications, 2) provide some background information on satellite capabilities for measuring pollutants, 3) discuss the many resources available to the end-user for accessing, processing, and visualizing the data, and 4) provide answers to common questions in plain language.
El Amraoui, L., J.-L. Attie, P. Ricaud, W. A. Lahoz, A. Piacentini, V.-H. Peuch, J. X. Warner, R. Abida, J. Barre, and R. Zbinden (2014), Tropospheric CO vertical profiles deduced from total columns using data assimilation: methodology and validation, Atmos. Meas. Tech., 7(9), 3035–3057, doi:10.5194/amt-7-3035-2014.
This paper presents a validation of a method to derive the vertical profile of carbon monoxide (CO) from its total column using data assimilation. We choose version 3 of MOPITT CO total columns to validate the proposed method. MOPITT products have the advantage of providing both the vertical profiles and the total columns of CO. Furthermore, this version has been extensively validated by comparison with many independent data sets, and has been used in many scientific studies. The first step of the paper consists in the specification of the observation errors based on the chi-square (chi(2)) test. The observations have been binned according to three types: over land during daytime, over land during night-time, and over sea. Their respective errors using the chi(2) metric have been found to be 8, 11 and 7 %. In the second step, the CO total columns, with their specified errors, are used within the assimilation system to estimate the vertical profiles. These are compared to the retrieved profiles of MOPITT V3 at global and regional scales. Generally, the two data sets show similar patterns and good agreement at both scales. Nevertheless, total column analyses slightly overestimate CO concentrations compared to MOPITT observations. The mean bias between both data sets is +15 and +12% at 700 and 250 hPa, respectively. In the third step, the assimilation of total column has been compared to the assimilation of MOPITT vertical profiles. The differences between both analyses are very small. In terms longitude-latitude maps, the mean bias between the two data sets is +6 and +8% at the pressure levels 700 and 200 hPa, respectively. In terms of zonal means, the CO distribution is similar for both analyses, with a mean bias which does not exceed 12 %. Finally, the two analyses have been validated using independent observations from the aircraft-based MOZAIC program in terms of vertical profiles over eight airports. Over most airports, both analyses agree well with aircraft profiles. For more than 50% of recorded measurements, the difference between the analyses and MOZAIC does not exceed 5 ppbv (parts per billion by volume).
Girach, I. A., and P. R. Nair (2014a), Carbon monoxide over Indian region as observed by MOPITT, Atmospheric Environment, 99, 599–609, doi:10.1016/j.atmosenv.2014.10.019.
A comprehensive study has been carried out on tropospheric carbon monoxide (CO) over the Indian land mass and surrounding oceanic region using the CO retrievals from MOPITT (Measurements of Pollution in the Troposphere) for a period of ∼14 years (2000–2014). The lower-tropospheric CO maximises during winter and shows a broad minimum during summer-monsoon over most of the regions, but with regionally varying seasonal amplitudes. Tropospheric column CO also exhibits a seasonal pattern similar to lower-tropospheric CO. But the upper-tropospheric CO shows an opposite seasonal pattern which peaks during summer monsoon. Columnar CO showed strong positive correlation with fire counts over west, east and north-east India, indicating the dominant role of biomass burning in controlling the seasonal variation of CO. The lower-tropospheric and columnar CO showed decreasing trend of 2.0–3.4 ppb year−1 (1.1–2.0% year−1) and 6.0–13.6 × 1015 molecules cm−2 year−1 (0.3–0.6% year−1) respectively over most of the regions. However, over many land regions trend in columnar CO is not significant. Most strikingly, the upper tropospheric CO showed increasing trend of 1.4–2.4 ppb year−1 (1.8–3.2% year−1). The analysis of biases in the estimated trends due to temporal changes in the MOPITT averaging kernels shows that magnitude of the realistic trend may change depending upon the bias but the sign (positive or negative) of trend remains the same. The decreasing trend in lower tropospheric and columnar CO could be attributed partly to increase in lower tropospheric water vapour and/or tropospheric ozone. The strengthening of convective activity, uplifting the CO to higher altitudes, could be a reason for increasing trend in the upper-tropospheric CO.
Girach, I. A., and P. R. Nair (2014b), On the vertical distribution of carbon monoxide over Bay of Bengal during winter: Role of water vapour and vertical updrafts, Journal of Atmospheric and Solar-Terrestrial Physics, 117, 31–47, doi:10.1016/j.jastp.2014.05.003.
The differences in the spatial pattern of column carbon monoxide (CO) and in-situ measured near-surface CO over Bay of Bengal (BoB) during winter were examined in the light of vertical distribution of CO as retrieved from MOPITT (Measurements Of Pollution In The Troposphere) on board Terra spacecraft. The column CO showed relatively high values over southern-BoB whereas the near-surface CO showed low mixing ratio indicating the existence of significant amount of CO at higher altitudes. The vertical profiles of CO over the BoB region retrieved from MOPITT exhibit a high altitude peak around ~9 km altitude region. The role of water vapour and convective activity/vertical updrafts in establishing the observed vertical profile of CO was investigated. It is found that CO got uplifted to the higher altitude due to updrafts and water vapour caused depletion of CO at lower altitudes which appeared as an apparent high in CO mixing ratio at higher altitude relative to that over lower altitude. The role of water vapour in the destruction of CO was confirmed by box model simulations. Airmass back-trajectory analysis showed that the long range transport from lower troposphere/boundary layer was also partially responsible for higher mixing ratios at higher altitude. In addition, a comparison of in-situ measured near-surface CO and those retrieved from MOPITT using retrieval algorithm Versions 4 and 5 showed that the points of discrepancy have reduced in the Version 5. Biomass burning and anthropogenic activities taking place over the Myanmar landmass was found to be responsible for the hot spots of near-surface-CO over the northeast-BoB.
Gonzi, S., P. I. Palmer, R. Paugam, M. Wooster, and M. N. Deeter (2014), Quantifying pyroconvective injection heights using observations of fire  energy: sensitivity of space-borne observations of carbon monoxide, Atmos. Chem. Phys. Discuss., 14(16), 22547–22585, doi:10.5194/acpd-14-22547-2014.
We use observations of fire size and fire radiative power (FRP) from the NASA Moderate-Resolution Imaging Spectroradiometers (MODIS), together with a parameterized plume rise model, to estimate biomass burning injection heights during 2006.  We use these injection heights in the GEOS-Chem atmospheric chemistry transport  model to  vertically distribute biomass burning emissions of carbon monoxide (CO) and to study the resulting atmospheric distribution. For 2006, we use over half a million FRP and fire size observations as input to the plume rise model.  We find that convective heat fluxes and actual fire sizes typically lie in the range of 1–100 kW m−2 and 0.001–100 ha, respectively, although in rare circumstances the convective heat flux can exceed 500 kW m−2.  The resulting injection heights have a skewed probability distribution  with approximately 80% of injections remaining within the local boundary layer (BL), with occasional injection height exceeding 8 km. We do not find a strong correlation between the FRP-inferred surface convective heat flux and the  resulting injection height, with environmental conditions often acting as a barrier to rapid vertical mixing even where the convective heat flux and  actual fire size are large. We also do not find a robust relationship between the underlying burnt vegetation type and the injection height. We find that CO columns calculated using the MODIS-inferred injection height (MODIS-inj) are typically  −9–+6% different to the control calculation in which emissions are emitted into the BL, with differences typically largest over the point of emission. After applying MOPITT v5 scene-dependent averaging kernels we find that we are much less sensitive to our choice of injection height profile.  The differences between the MOPITT and the model CO columns (max bias ≈ 50%), due largely to uncertainties in emission inventories, are much larger than those introduced by the injection heights. We show that including a realistic diurnal variation in FRP (peaking in the afternoon) or accounting for subgrid-scale emission errors does not alter our main conclusions. Finally, we use a Bayesian maximum a posteriori approach constrained by MOPITT CO profiles to estimate the CO emissions but because of the inherent bias between model and MOPITT  we find little impact on the resulting emission estimates. Studying the role of pyroconvection in distributing gases and particles in the atmosphere using global MOPITT CO observations (or any current space-borne measurement of the atmosphere) is still associated with large errors,  with the exception of a small subset of large fires and favourable environmental conditions, which will consequently lead to a bias in any analysis on a global scale.
Henderson, B. H., F. Akhtar, H. O. T. Pye, S. L. Napelenok, and W. T. Hutzell (2014), A database and tool for boundary conditions for regional air quality modeling: description and evaluation, Geosci. Model Dev., 7(1), 339–360, doi:10.5194/gmd-7-339-2014.
Transported air pollutants receive increasing attention as regulations tighten and global concentrations increase. The need to represent international transport in regional air quality assessments requires improved representation of boundary concentrations. Currently available observations are too sparse vertically to provide boundary information, particularly for ozone precursors, but global simulations can be used to generate spatially and temporally varying lateral boundary conditions (LBC). This study presents a public database of global simulations designed and evaluated for use as LBC for air quality models (AQMs). The database covers the contiguous United States (CONUS) for the years 2001–2010 and contains hourly varying concentrations of ozone, aerosols, and their precursors. The database is complemented by a tool for configuring the global results as inputs to regional scale models (e.g., Community Multiscale Air Quality or Comprehensive Air quality Model with extensions). This study also presents an example application based on the CONUS domain, which is evaluated against satellite retrieved ozone and carbon monoxide vertical profiles. The results show performance is largely within uncertainty estimates for ozone from the Ozone Monitoring Instrument and carbon monoxide from the Measurements Of Pollution In The Troposphere (MOPITT), but there were some notable biases compared with Tropospheric Emission Spectrometer (TES) ozone. Compared with TES, our ozone predictions are high-biased in the upper troposphere, particularly in the south during January. This publication documents the global simulation database, the tool for conversion to LBC, and the evaluation of concentrations on the boundaries. This documentation is intended to support applications that require representation of long-range transport of air pollutants.
de Laat, A. T. J., I. Aben, M. Deeter, P. Nédélec, H. Eskes, J.-L. Attié, P. Ricaud, R. Abida, L. El Amraoui, and J. Landgraf (2014), Validation of nine years of MOPITT V5 NIR using MOZAIC/IAGOS measurements: biases and long-term stability, Atmos. Meas. Tech., 7(11), 3783–3799, doi:10.5194/amt-7-3783-2014.
Validation results from a comparison between Measurement Of Pollution In The Troposphere (MOPITT) V5 Near InfraRed (NIR) carbon monoxide (CO) total column measurements and Measurement of Ozone and Water Vapour on Airbus in-service Aircraft (MOZAIC)/In-Service Aircraft for a Global Observing System (IAGOS) aircraft measurements are presented. A good agreement is found between MOPITT and MOZAIC/IAGOS measurements, consistent with results from earlier studies using different validation data and despite large variability in MOPITT CO total columns along the spatial footprint of the MOZAIC/IAGOS measurements. Validation results improve when taking the large spatial footprint of the MOZAIC/IAGOS data into account. No statistically significant drift was detected in the validation results over the period 2002–2010 at global, continental and local (airport) scales. Furthermore, for those situations where MOZAIC/IAGOS measurements differed from the MOPITT a priori, the MOPITT measurements clearly outperformed the MOPITT a priori data, indicating that MOPITT NIR retrievals add value to the MOPITT a priori. Results from a high spatial resolution simulation of the chemistry-transport model MOCAGE (MOdèle de Chimie Atmosphérique à Grande Echelle) showed that the most likely explanation for the large MOPITT variability along the MOZAIC-IAGOS profile flight path is related to spatio-temporal CO variability, which should be kept in mind when using MOZAIC/IAGOS profile measurements for validating satellite nadir observations.
Laken, B. A., and T. Shahbaz (2014), Satellite-Detected Carbon Monoxide Pollution during 2000–2012: Examining Global Trends and also Regional Anthropogenic Periods over China, the EU and the USA, Climate, 2(1), 1–16, doi:10.3390/cli2010001.
In this paper, we test if any statistically significant periodicities are detectable in carbon monoxide emissions over China, the European Union, and the United States of America. To do this, we performed a period analysis using 10 years of daily-averaged data, from the Measurements Of Pollution In The Troposphere (MOPITT) instrument. Besides a seasonal period, we found no clearly detectable periods at any timescale with the exception of a strong signal at 2.28 days. This period was observed over all tested regions and persisted when larger (hemisphere-wide) regions were considered. However, rather than resulting from a physical variation in carbon monoxide, it resulted from day-to-day changes in the area covered by MOPITT on-board its polar-orbiting satellite platform. We also examined linear trends over the dataset, and found that MOPITT identifies several centers of increasing carbon monoxide concentration—the largest being over China—although globally MOPITT reports a significant decrease in carbon monoxide has occurred over the past decade.
Liu, C., S. Beirle, T. Butler, P. Hoor, C. Frankenberg, P. Jöckel, M. Penning de Vries, U. Platt, A. Pozzer, M. G. Lawrence, J. Lelieveld, H. Tost, and T. Wagner (2014), Profile information on CO from SCIAMACHY observations using cloud slicing and comparison with model simulations, Atmos. Chem. Phys., 14(3), 1717–1732, doi:10.5194/acp-14-1717-2014.
We apply a cloud slicing technique (CST), originally developed for Total Ozone Mapping Spectrometer (TOMS) ozone observations, to CO vertical column densities retrieved from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). CST makes use of the shielding effect of clouds and combines trace gas column measurements of cloudy pixels with different cloud heights to retrieve fractional columns aloft. Here we determine seasonal mean tropospheric CO profiles at a vertical resolution of about 1 km, which is much finer than what can be obtained from thermal infrared (IR) instruments. However, since both the atmospheric CO profiles and the effective cloud heights depend systematically on meteorology, and in addition part of the retrieved signal originates from the clear part of the satellite ground pixel, the profiles retrieved from the CST have to be interpreted with care. We compare the seasonal mean SCIAMACHY CO profiles with the output from two atmospheric models sampled in the same way as the satellite observations. We find in general good agreement of the spatial patterns, but systematic differences in the absolute values are observed in both hemispheres (more strongly in the Northern Hemisphere), indicating that the source strengths in the emission inventories are probably underestimated.
Martínez-Alonso, S., M. N. Deeter, H. M. Worden, J. C. Gille, L. K. Emmons, L. L. Pan, M. Park, G. L. Manney, P. F. Bernath, C. D. Boone, K. A. Walker, F. Kolonjari, S. C. Wofsy, J. Pittman, and B. C. Daube (2014), Comparison of Upper Tropospheric Carbon Monoxide from MOPITT, ACE-FTS, and HIPPO-QCLS, J. Geophys. Res. Atmos., 2014JD022397, doi:10.1002/2014JD022397.
Products from the Measurements Of Pollution In The Troposphere (MOPITT) instrument are regularly validated using in situ airborne measurements. However, few of these measurements reach into the upper troposphere, thus hindering MOPITT validation in that region. Here we evaluate upper tropospheric (~500 hPa to the tropopause) MOPITT CO profiles by comparing them to satellite Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) retrievals and to measurements from the High-performance Instrumented Airborne Platform for Environmental Research Pole to Pole Observations (HIPPO) Quantum Cascade Laser Spectrometer (QCLS). Direct comparison of co-located v5 MOPITT thermal-infrared-only retrievals, v3.0 ACE-FTS retrievals, and HIPPO-QCLS measurements show a slight positive MOPITT CO bias within its 10% accuracy requirement with respect to the other two datasets. Direct comparison of co-located ACE-FTS and HIPPO-QCLS measurements results in a small number of samples, due to the large disparity in sampling pattern and density of these datasets. Thus, two additional indirect techniques for comparison of non-coincident datasets have been applied: tracer-tracer (CO-O3) correlation analysis and analysis of profiles in tropopause coordinates. These techniques suggest a negative bias of ACE-FTS with respect to HIPPO-QCLS; this could be caused by differences in resolution (horizontal, vertical) or by deficiencies in the ACE-FTS CO retrievals below ~20 km of altitude, among others. We also investigate the temporal stability of MOPITT and ACE-FTS data, which provide unique global CO records and are thus important in climate analysis. Our results indicate that the relative bias between the two datasets has remained generally stable during the 2004–2010 period.
Miyazaki, K., H. J. Eskes, K. Sudo, and C. Zhang (2014), Global lightning NOx production estimated by an assimilation of multiple satellite data sets, Atmos. Chem. Phys., 14(7), 3277–3305, doi:10.5194/acp-14-3277-2014.
The global source of lightning-produced NOx (LNOx) is estimated by assimilating observations of NO2, O3, HNO3, and CO measured by multiple satellite measurements into a chemical transport model. Included are observations from the Ozone Monitoring Instrument (OMI), Microwave Limb Sounder (MLS), Tropospheric Emission Spectrometer (TES), and Measurements of Pollution in the Troposphere (MOPITT) instruments. The assimilation of multiple chemical data sets with different vertical sensitivity profiles provides comprehensive constraints on the global LNOx source while improving the representations of the entire chemical system affecting atmospheric NOx, including surface emissions and inflows from the stratosphere. The annual global LNOx source amount and NO production efficiency are estimated at 6.3 Tg N yr−1 and 310 mol NO flash−1, respectively. Sensitivity studies with perturbed satellite data sets, model and data assimilation settings lead to an error estimate of about  1.4 Tg N yr−1 on this global LNOx source. These estimates are significantly different from those estimated from a parameter inversion that optimizes only the LNOx source from NO2 observations alone, which may lead to an overestimate of the source adjustment. The total LNOx source is predominantly corrected by the assimilation of OMI NO2 observations, while TES and MLS observations add important constraints on the vertical source profile. The results indicate that the widely used lightning parameterization based on the C-shape assumption underestimates the source in the upper troposphere and overestimates the peak source height by up to about 1 km over land and the tropical western Pacific. Adjustments are larger over ocean than over land, suggesting that the cloud height dependence is too weak over the ocean in the Price and Rind (1992) approach. The significantly improved agreement between the analyzed ozone fields and independent observations gives confidence in the performance of the LNOx source estimation.
Penrod, A., Y. Zhang, K. Wang, S.-Y. Wu, and L. R. Leung (2014), Impacts of future climate and emission changes on U.S. air quality, Atmospheric Environment, 89, 533–547, doi:10.1016/j.atmosenv.2014.01.001.
Changes in climate and emissions will affect future air quality. In this work, simulations of regional air quality during current (2001–2005) and future (2026–2030) winter and summer are conducted with the newly released CMAQ version 5.0 to examine the impacts of simulated future climate and anthropogenic emission projections on air quality over the U.S. Current meteorological and chemical predictions are evaluated against observations to assess the model’s capability in reproducing the seasonal differences. WRF and CMAQ capture the overall observational spatial patterns and seasonal differences. Biases in model predictions are attributed to uncertainties in emissions, boundary conditions, and limitations in model physical and chemical treatments as well as the use of a coarse grid resolution. Increased temperatures (up to 3.18 °C) and decreased ventilation (up to 157 m in planetary boundary layer height) are found in both future winter and summer, with more prominent changes in winter. Increases in future temperatures result in increased isoprene and terpene emissions in winter and summer, driving the increase in maximum 8-h average O3 (up to 5.0 ppb) over the eastern U.S. in winter while decreases in NOx emissions drive the decrease in O3 over most of the U.S. in summer. Future PM2.5 concentrations in winter and summer and many of its components decrease due to decreases in primary anthropogenic emissions and the concentrations of secondary anthropogenic pollutants as well as increased precipitation in winter. Future winter and summer dry and wet deposition fluxes are spatially variable and increase with decreasing surface resistance and precipitation, respectively. They decrease with a decrease in ambient particulate concentrations. Anthropogenic emissions play a more important role in summer than in winter for future O3 and PM2.5 levels, with a dominance of the effects of significant emission reductions over those of climate change on future PM2.5 levels.
Pommrich, R., R. Müller, J.-U. Grooß, P. Konopka, F. Ploeger, B. Vogel, M. Tao, C. M. Hoppe, G. Günther, N. Spelten, L. Hoffmann, H.-C. Pumphrey, S. Viciani, F. D’Amato, C. M. Volk, P. Hoor, H. Schlager, and M. Riese (2014), Tropical troposphere to stratosphere transport of carbon monoxide and long-lived trace species in the Chemical Lagrangian Model of the Stratosphere (CLaMS), Geosci. Model Dev., 7(6), 2895–2916, doi:10.5194/gmd-7-2895-2014.
Variations in the mixing ratio of trace gases of tropospheric origin entering the stratosphere in the tropics are of interest for assessing both troposphere to stratosphere transport fluxes in the tropics and the impact of these transport fluxes on the composition of the tropical lower stratosphere.  Anomaly patterns of carbon monoxide (CO) and long-lived tracers in the lower tropical stratosphere allow conclusions about the rate and the variability of tropical upwelling to be drawn.  Here, we present a simplified chemistry scheme for the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the simulation, at comparatively low numerical cost, of CO, ozone, and long-lived trace substances (CH4, N2O, CCl3F (CFC-11), CCl2F2 (CFC-12), and CO2) in the lower tropical stratosphere.  For the long-lived trace substances, the boundary conditions at the surface are prescribed based on ground-based measurements in the lowest model level.  The boundary condition for CO in the lower troposphere (below about 4 km) is deduced from MOPITT measurements. Due to the lack of a specific representation of mixing and convective uplift in the troposphere in this model version, enhanced CO values, in particular those resulting from convective outflow are underestimated. However, in the tropical tropopause layer and the lower tropical stratosphere, there is relatively good agreement of simulated CO with in situ measurements (with the exception of the TROCCINOX campaign, where CO in the simulation is biased low ≈10–15 ppbv).  Further, the model results (and therefore also the ERA-Interim winds, on which the transport in the model is based) are of sufficient quality to describe large scale anomaly patterns of CO in the lower stratosphere.  In particular, the zonally averaged tropical CO anomaly patterns (the so called “tape recorder” patterns) simulated by this model version of CLaMS are in good agreement with observations, although the simulations show a too rapid upwelling compared to observations as a consequence of the overestimated vertical velocities in the ERA-Interim reanalysis data set.  Moreover, the simulated tropical anomaly patterns of N2O are in good agreement with observations. In the simulations, anomaly patterns of CH4 and CFC-11 were found to be very similar to those of N2O; for all long-lived tracers, positive anomalies are simulated because of the enhanced tropical upwelling in the easterly shear phase of the quasi-biennial oscillation.
Rosenfeld, D., M. O. Andreae, A. Asmi, M. Chin, G. de Leeuw, D. P. Donovan, R. Kahn, S. Kinne, N. Kivekäs, M. Kulmala, W. Lau, K. S. Schmidt, T. Suni, T. Wagner, M. Wild, and J. Quaas (2014), Global observations of aerosol-cloud-precipitation-climate interactions, Rev. Geophys., 2013RG000441, doi:10.1002/2013RG000441.
Cloud drop condensation nuclei (CCN) and ice nuclei (IN) particles determine to a large extent cloud microstructure and, consequently, cloud albedo and the dynamic response of clouds to aerosol-induced changes to precipitation. This can modify the reflected solar radiation and the thermal radiation emitted to space. Measurements of tropospheric CCN and IN over large areas have not been possible and can be only roughly approximated from satellite-sensor-based estimates of optical properties of aerosols. Our lack of ability to measure both CCN and cloud updrafts precludes disentangling the effects of meteorology from those of aerosols and represents the largest component in our uncertainty in anthropogenic climate forcing. Ways to improve the retrieval accuracy include multiangle and multipolarimetric passive measurements of the optical signal and multispectral lidar polarimetric measurements. Indirect methods include proxies of trace gases, as retrieved by hyperspectral sensors. Perhaps the most promising emerging direction is retrieving the CCN properties by simultaneously retrieving convective cloud drop number concentrations and updraft speeds, which amounts to using clouds as natural CCN chambers. These satellite observations have to be constrained by in situ observations of aerosol-cloud-precipitation-climate (ACPC) interactions, which in turn constrain a hierarchy of model simulations of ACPC. Since the essence of a general circulation model is an accurate quantification of the energy and mass fluxes in all forms between the surface, atmosphere and outer space, a route to progress is proposed here in the form of a series of box flux closure experiments in the various climate regimes. A roadmap is provided for quantifying the ACPC interactions and thereby reducing the uncertainty in anthropogenic climate forcing.
Safronov, A. N., E. V. Fokeeva, V. S. Rakitin, E. I. Grechko, and R. A. Shumsky (2014), Severe Wildfires Near Moscow, Russia in 2010: Modeling of Carbon Monoxide Pollution and Comparisons with Observations, Remote Sens., 7(1), 395–429, doi:10.3390/rs70100395.
The spatial and temporal distributions of the carbon monoxide (CO) concentration were calculated with the Regional Atmospheric Modeling System and Hybrid Particle and Concentration Transport model (RAMS/HYPACT) in the provinces near Moscow during the abnormally hot summer of 2010. The forest, steppe and meadow hot spots were defined by the satellite data MCD14ML (MODIS Terra and Aqua satellite data). The calculations indicated that the surface CO concentrations from the model were two times less than the experimental data obtained from the Moscow State University (MSU) station and Zvenigorod Scientific Station (ZSS). Conversely, the total column CO concentrations obtained from the model were two to three times larger than the experimental values obtained from the Obukhov Institute of Atmospheric Physics (OIAP) and ZSS stations. The vertical transfer of pollutants was overestimated. Tentatively, it could be assumed that an aerosol influence in the model calculations is a reason for the overestimation. The comparisons between the wind speed, temperature and humidity profiles calculated in the model with the data from the standard balloon sounding exhibited good agreement. The CO total column data of the Measurements of Pollution in the Troposphere (MOPITTv5 NIR and TIR/NIR) obtained from the OIAP and ZSS stations appear more realistic than do the MOPITTv4 data. However, the surface MOPITT values of CO concentration for Moscow have the large distinction from the ground measurements. A careful proposal regarding satellite orbit optimization was made, which could improve future spectrometric measurements, such as the MOPITT, Atmospheric Infrared Sounder (AIRS) and Infrared Atmospheric Sounding Interferometer (IASI) measurements.
Stein, O., M. G. Schultz, I. Bouarar, H. Clark, V. Huijnen, A. Gaudel, M. George, and C. Clerbaux (2014), On the wintertime low bias of Northern Hemisphere carbon monoxide found in global model simulations, Atmos. Chem. Phys., 14(17), 9295–9316, doi:10.5194/acp-14-9295-2014.
Despite the developments in the global modelling of chemistry and of the parameterization of the physical processes, carbon monoxide (CO) concentrations remain underestimated during Northern Hemisphere (NH) winter by most state-of-the-art chemistry transport models. The consequential model bias can in principle originate from either an underestimation of CO sources or an overestimation of its sinks. We address both the role of surface sources and sinks with a series of MOZART (Model for Ozone And Related Tracers) model sensitivity studies for the year 2008 and compare our results to observational data from ground-based stations, satellite observations, and vertical profiles from measurements on passenger aircraft. In our base case simulation using MACCity (Monitoring Atmospheric Composition and Climate project) anthropogenic emissions, the near-surface CO mixing ratios are underestimated in the Northern Hemisphere by more than 20 ppb from December to April, with the largest bias of up to 75 ppb over Europe in January. An increase in global biomass burning or biogenic emissions of CO or volatile organic compounds (VOCs) is not able to reduce the annual course of the model bias and yields concentrations over the Southern Hemisphere which are too high. Raising global annual anthropogenic emissions with a simple scaling factor results in overestimations of surface mixing ratios in most regions all year round. Instead, our results indicate that anthropogenic CO and, possibly, VOC emissions in the MACCity inventory are too low for the industrialized countries only during winter and spring. Reasonable agreement with observations can only be achieved if the CO emissions are adjusted seasonally with regionally varying scaling factors. A part of the model bias could also be eliminated by exchanging the original resistance-type dry deposition scheme with a parameterization for CO uptake by oxidation from soil bacteria and microbes, which reduces the boreal winter dry deposition fluxes. The best match to surface observations, satellite retrievals, and aircraft observations was achieved when the modified dry deposition scheme was combined with increased wintertime road traffic emissions over Europe and North America (factors up to 4.5 and 2, respectively). One reason for the apparent underestimation of emissions may be an exaggerated downward trend in the Representative Concentration Pathway (RCP) 8.5 scenario in these regions between 2000 and 2010, as this scenario was used to extrapolate the MACCity emissions from their base year 2000. This factor is potentially amplified by a lack of knowledge about the seasonality of emissions. A methane lifetime of 9.7 yr for our basic model and 9.8 yr for the optimized simulation agrees well with current estimates of global OH, but we cannot fully exclude a potential effect from errors in the geographical and seasonal distribution of OH concentrations on the modelled CO.
Sukitpaneenit, M., and N. T. K. Oanh (2014), Satellite monitoring for carbon monoxide and particulate matter during forest fire episodes in Northern Thailand, Environ. Monit. Assess., 186(4), 2495–2504, doi:10.1007/s10661-013-3556-x.
This study explored the use of satellite data to monitor carbon monoxide (CO) and particulate matter (PM) in Northern Thailand during the dry season when forest fires are known to be an important cause of air pollution. Satellite data, including Measurement of Pollution in the Troposphere (MOPITT) CO, Moderate Resolution Imaging Spectroradiometer aerosol optical depth (MODIS AOD), and MODIS fire hotspots, were analyzed with air pollution data measured at nine automatic air quality monitoring stations in the study area for February-April months of 2008-2010. The correlation analysis showed that daily CO and PM with size below 10 mu m (PM10) were associated with the forest fire hotspot counts, especially in the rural areas with the maximum correlation coefficient (R) of 0.59 for CO and 0.65 for PM10. The correlations between MODIS AOD and PM10, between MOPITT CO and CO, and between MODIS AOD and MOPITT CO were also analyzed, confirming the association between these variables. Two forest fire episodes were selected, and the dispersion of pollution plumes was studied using the MOPITT CO total column and MODIS AOD data, together with the surface wind vectors. The results showed consistency between the plume dispersion, locations of dense hotspots, ground monitoring data, and prevalent winds. The satellite data were shown to be useful in monitoring the regional transport of forest fire plumes.
Wang, K., Y. Zhang, K. Yahya, S.-Y. Wu, and G. Grell (2014), Implementation and Initial Application of New Chemistry-Aerosol Options in WRF/Chem for Simulating Secondary Organic Aerosols and Aerosol Indirect Effects for Regional Air Quality, Atmospheric Environment, doi:10.1016/j.atmosenv.2014.12.007. [online] Available from: http://www.sciencedirect.com/science/article/pii/S1352231014009558 .
Atmospheric aerosols play important roles in affecting regional meteorology and air quality through aerosol direct and indirect effects. Two new chemistry-aerosol options have been developed in WRF/Chem v3.4.1 by incorporating the 2005 Carbon Bond (CB05) mechanism and coupling it with the existing aerosol module MADE with SORGAM and VBS modules for simulating secondary organic aerosol (SOA), aqueous-phase chemistry in both large scale and convective clouds, and aerosol feedback processes (hereafter CB05-MADE/SORGAM and CB05-MADE/VBS). As part of the Air Quality Model Evaluation International Initiative (AQMEII) Phase II model intercomparison that focuses on online-coupled meteorology and chemistry models, WRF/Chem with the two new options is applied to an area over North America for July 2006 episode. The simulations with both options can reproduce reasonably well most of the observed meteorological variables, chemical concentrations, and aerosol/cloud properties. Compared to CB05-MADE/SORGAM, CB05-MADE/VBS greatly improves the model performance for organic carbon (OC) and PM2.5, reducing NMBs from -81.2% to -13.1% and from -26.1% to -15.6%, respectively. Sensitivity simulations show that the aerosol indirect effects (including aqueous-phase chemistry) can reduce the net surface solar radiation by up to 53 W m-2 with a domainwide mean of 12 W m-2 through affecting cloud formation and radiation scattering and reflection by increasing cloud cover, which in turn reduce the surface temperature, NO2 photolytic rate, and planetary boundary layer height by up to 0.3 °C, 3.7 min-1, and 64 m, respectively. The changes of those meteorological variables further impact the air quality through the complex chemistry-aerosol-cloud-radiation interactions by reducing O3 mixing ratios by up to 5.0 ppb. The results of this work demonstrate the importance of aerosol indirect effects on the regional climate and air quality. For comparison, the impacts of aerosol direct effects on both regional meteorology and air quality are much lower with the reduction on net surface solar radiation only by up to 17 W m-2 and O3 only by up to 1.4 ppb, which indicates the importance and necessity to accurately represent the aerosol indirect effects in the online-couple regional models.
Worden, H. M., M. N. Deeter, D. P. Edwards, J. Gille, J. Drummond, L. K. Emmons, G. Francis, and S. Martínez-Alonso (2014), 13 years of MOPITT operations: lessons from MOPITT retrieval algorithm development, Ann. Geophys., 56(0), doi:10.4401/ag-6330. [online] Available from: http://www.annalsofgeophysics.eu/index.php/annals/article/view/6330.
The Measurements of Pollution in the Troposphere (MOPITT) instrument on the NASA Terra platform has now acquired over thirteen years of global tropospheric carbon monoxide (CO) observations, forming the longest satellite record for an important pollutant. MOPITT products are routinely exploited for characterizing CO sources and for analyzing air quality. For retrieving CO concentrations in the lower troposphere, MOPITT is equipped with both thermal-infrared and near-infrared channels.
Yoon, J., and A. Pozzer (2014), Model-simulated trend of surface carbon monoxide for the 2001–2010 decade, Atmos. Chem. Phys., 14(19), 10465–10482, doi:10.5194/acp-14-10465-2014.
We present decadal trend estimates of surface carbon monoxide (CO) simulated using the atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC; ECHAM5 and MESSy stand for fifth-generation European Centre Hamburg general circulation model and Modular Earth Submodel System, respectively) based on the emission scenarios Representative Concentration Pathways (RCP) 8.5 for anthropogenic activity and Global Fire Emissions Database (GFED) v3.1 for biomass burning from 2001 through 2010. The spatial distribution of the modeled surface CO is evaluated with monthly data from the Measurements Of Pollution In The Troposphere (MOPITT) thermal infrared product. The global means of correlation coefficient and relative bias for the decade 2001–2010 are 0.95 and −4.29%, respectively. We also find a reasonable correlation (R = 0.78) between the trends of EMAC surface CO and full 10-year monthly records from ground-based observation (World Data Centre for Greenhouse Gases, WDCGG). Over western Europe, eastern USA, and northern Australia, the significant decreases in EMAC surface CO are estimated at −35.5 ± 5.8, −59.6 ± 9.1, and −13.7 ± 9.5 ppbv decade−1, respectively. In contrast, the surface CO increases by +8.9 ± 4.8 ppbv decade−1 over southern Asia. A high correlation (R = 0.92) between the changes in EMAC-simulated surface CO and total emission flux shows that the significant regional trends are attributed to the changes in primary and direct emissions from both anthropogenic activity and biomass burning.
Yumimoto, K., I. Uno, and S. Itahashi (2014), Long-term inverse modeling of Chinese CO emission from satellite observations, Environ. Pollut., 195, 308–318, doi:10.1016/j.envpol.2014.07.026.
Carbon monoxide (CO) emissions in China in 2005-2010 were estimated by inversion, using the Green’s function method from vertical CO profiles derived from MOPITT Version 5 satellite data and a tagged CO simulation, and validated with independent in situ observations from the World Data Centre for Greenhouse Gases. Modeling with a posteriori emission successfully reproduced CO outflow from the continent to the East China Sea, Sea of Japan, and Japanese islands during winter and spring, and compensated for underestimates in central and eastern China in summer. A posteriori emissions showed large seasonal variations in which December and March emissions were on average 23% larger than August emissions, consistent with other studies. Estimated Chinese CO emissions were 184.4, 173.1, 184.6, 158.4, 157.4, and 157.3 Tg/year for 2005-2010, respectively. The decrease after 2007 is partly attributed to Chinese socioeconomic conditions and improved combustion efficiency. (C) 2014 Elsevier Ltd. All rights reserved.
Zoogman, P., D. J. Jacob, K. Chance, H. M. Worden, D. P. Edwards, and L. Zhang (2014), Improved monitoring of surface ozone by joint assimilation of geostationary satellite observations of ozone and CO, Atmospheric Environment, 84, 254–261, doi:10.1016/j.atmosenv.2013.11.048.
Future geostationary satellite observations of tropospheric ozone aim to improve monitoring of surface ozone air quality. However, ozone retrievals from space have limited sensitivity in the lower troposphere (boundary layer). Data assimilation in a chemical transport model can propagate the information from the satellite observations to provide useful constraints on surface ozone. This may be aided by correlated satellite observations of carbon monoxide (CO), for which boundary layer sensitivity is easier to achieve. We examine the potential of concurrent geostationary observations of ozone and CO to improve constraints on surface ozone air quality through exploitation of ozone–CO model error correlations in a joint data assimilation framework. The hypothesis is that model transport errors diagnosed for CO provide information on corresponding errors in ozone. A paired-model analysis of ozone–CO error correlations in the boundary layer over North America in summer indicates positive error correlations in continental outflow but negative regional-scale error correlations over land, the latter reflecting opposite sensitivities of ozone and CO to boundary layer depth. Aircraft observations from the ICARTT campaign are consistent with this pattern but also indicate strong positive error correlations in fine-scale pollution plumes. We develop a joint ozone–CO data assimilation system and apply it to a regional-scale Observing System Simulation Experiment (OSSE) of the planned NASA GEO-CAPE geostationary mission over North America. We find substantial benefit from joint ozone–CO data assimilation in informing US ozone air quality if the instrument sensitivity for CO in the boundary layer is greater than that for ozone. A high-quality geostationary measurement of CO could potentially relax the requirements for boundary layer sensitivity of the ozone measurement. This is contingent on accurate characterization of ozone–CO error correlations. A finer-resolution data assimilation system resolving the urban scale would need to account for the change in sign of the ozone–CO error correlations between urban pollution plumes and the regional atmosphere.

2013

Barré, J., L. El Amraoui, P. Ricaud, W. A. Lahoz, J.-L. Attié, V.-H. Peuch, B. Josse, and V. Marécal (2013), Diagnosing the transition layer at extratropical latitudes using MLS O3 and MOPITT CO analyses, Atmos. Chem. Phys., 13(14), 7225–7240, doi:10.5194/acp-13-7225-2013.
The behavior of the extratropical transition layer (ExTL) is investigated using a chemistry transport model (CTM) and analyses derived from assimilation of MLS (Microwave Limb Sounder) O-3 and MOPITT (Measurements Of Pollution In The Troposphere) CO data. We firstly focus on a stratosphere-troposphere exchange (STE) case study that occurred on 15 August 2007 over the British Isles (50 degrees N, 10 degrees W). We evaluate the effect of data assimilation on the O-3-CO correlations. It is shown that data assimilation disrupts the relationship in the transition region. When MLS O-3 is assimilated, CO and O-3 values are not consistent between each other, leading to unphysical correlations at the STE location. When MLS O-3 and MOPITT CO assimilated fields are taken into account in the diagnostics the relationship happens to be more physical. We then use O-3-CO correlations to quantify the effect of data assimilation on the height and depth of the ExTL. When the free-model run O-3 and CO fields are used in the diagnostics, the ExTL distribution is found 1.1 km above the thermal tropopause and is 2.6 km wide (2 sigma). MOPITT CO analyses only slightly sharpen (by -0.02 km) and lower (by -0.2 km) the ExTL distribution. MLS O-3 analyses provide an expansion (by +0.9 km) of the ExTL distribution, suggesting a more intense O-3 mixing. However, the MLS O-3 analyses ExTL distribution shows a maximum close to the thermal tropopause and a mean location closer to the thermal tropopause (+0.45 km). When MLS O-3 and MOPITT CO analyses are used together, the ExTL shows a mean location that is the closest to the thermal tropopause (+0.16 km). We also extend the study at the global scale on 15 August 2007 and for the month of August 2007. MOPITT CO analyses still show a narrower chemical transition between stratosphere and troposphere than the free-model run. MLS O-3 analyses move the ExTL toward the troposphere and broaden it. When MLS O-3 analyses and MOPITT CO analyses are used together, the ExTL matches the thermal tropopause poleward of 50 degrees.
Cheng, L., B. Wen-Guang, Z. Xing-Ying, and Z. Peng (2013), An improvement of retrieving carbon monoxide from SCIAMACHY Part I: with respect to the instrumental issues, Chinese J. Geophys.-Chinese Ed., 56(3), 758–769, doi:10.6038/cjg20130305.
SCIAMACHY on board the European ENVISAT satellite is the only one spectrometer, which could quantitatively determine the total column densities of the greenhouse gases CO2, CH4, as well as of CO from near-infrared spectral band. Compared to other thermal infrared satellite (MOPITT, IASI, AIRS, etc.), SCIAMACHY is more sensitive to low atmosphere where the strong source are located. However, the CO retrieval turned out not only to be a challenging task from a spectroscopic point of view, but also complicated by a serious instrument issue, the ice layer deposit on the SCIAMACHY near-infrared channels. This deposit ice layer yields systematic biases on SCIAMACHY CO VCD measurements, which are up to 100% and not only depend on location, but also vary with time. The accurate correction is essential, since inaccurate corrections will lead to a wrong interpretation of the results. Currently, there are several correction methods. developed by different groups, but no consistent time series could be retrieved so far. In this paper, similar correction procedures are developed and validated at first. In addition to the existing correction methods, a completely new correction method is then developed. To validate the new SCIAMACHY CO product, we compare it with the independent ground based FTIR measurements. After the correction, the agreement of the seasonal patterns greatly improves; the relative differences between the two dataset reduce from 60% to less than 5%, which make the precisely satellite measurements possible. The results not only could improve our knowledge of the sources and sinks, but most importantly, also could help government formulate carbon reduction rules, effectively reduce the greenhouse effect.
Deeter, M. N., S. Martínez-Alonso, D. P. Edwards, L. K. Emmons, J. C. Gille, H. M. Worden, J. V. Pittman, B. C. Daube, and S. C. Wofsy (2013), Validation of MOPITT Version 5 thermal-infrared, near-infrared, and multispectral carbon monoxide profile retrievals for 2000–2011, Journal of Geophysical Research: Atmospheres, n/a–n/a, doi:10.1002/jgrd.50272.
Validation results are reported for the MOPITT (Measurements of Pollution in the Troposphere) “Version 5” (V5) product for tropospheric carbon monoxide (CO) and are compared to results for the “Version 4” product. The V5 retrieval algorithm introduces (1) a method for reducing retrieval bias drift associated with long-term instrumental degradation, (2) a more exact representation of the effects of random errors in the radiances and, for the first time, (3) the use of MOPITT’s near-infrared (NIR) radiances to complement the thermal-infrared (TIR) radiances. Exploiting TIR and NIR radiances together facilitates retrievals of CO in the lowermost troposphere. V5 retrieval products based (1) solely on TIR measurements, (2) solely on NIR measurements and (3) on both TIR and NIR measurements are separately validated and analyzed. Actual retrieved CO profiles and total columns are compared with equivalent retrievals based on in situ measurements from (1) routine NOAA aircraft sampling mainly over North America and (2) the “HIAPER Pole to Pole Observations” (HIPPO) field campaign. Particular attention is focused on the long-term stability and geographical uniformity of the retrieval errors. Results for the retrieved total column clearly indicate reduced temporal bias drift in the V5 products compared to the V4 product, and do not exhibit a positive bias in the Southern Hemisphere, which is evident in the V4 product.
He, H., J. W. Stehr, J. C. Hains, D. J. Krask, B. G. Doddridge, K. Y. Vinnikov, T. P. Canty, K. M. Hosley, R. J. Salawitch, H. M. Worden, and R. R. Dickerson (2013), Trends in emissions and concentrations of air pollutants in the lower troposphere in the Baltimore/Washington airshed from 1997 to 2011, Atmos. Chem. Phys., 13(15), 7859–7874, doi:10.5194/acp-13-7859-2013.
Trends in the composition of the lower atmosphere (0–1500 m altitude) and surface air quality over the Baltimore/Washington area and surrounding states were investigated for the period from 1997 to 2011. We examined emissions of ozone precursors from monitors and inventories as well as ambient ground-level and aircraft measurements to characterize trends in air pollution. The US EPA Continuous Emissions Monitoring System (CEMS) program reported substantial decreases in emission of summertime nitrogen oxides (NOx) from power plants, up to ∼80% in the mid-Atlantic States. These large reductions in emission of NOx are reflected in a sharp decrease of ground-level concentrations of NOx starting around 2003. The decreasing trend of tropospheric column CO observed by aircraft is ∼0.8 Dobson unit (DU) per year, corresponding to ∼35 ppbv yr−1 in the lower troposphere (the surface to 1500 m above ground level). Satellite observations of long-term, near-surface CO show a ∼40% decrease over western Maryland between 2000 and 2011; the same magnitude is indicated by aircraft measurements above these regions upwind of the Baltimore/Washington airshed. With decreasing emissions of ozone precursors, the ground-level ozone in the Baltimore/Washington area shows a 0.6 ppbv yr−1 decrease in the past 15 yr. Since photochemical production of ozone is substantially influenced by ambient temperature, we introduce the climate penalty factor (CPF) into the trend analysis of long-term aircraft measurements. After compensating for inter-annual variations in temperature, historical aircraft measurements indicate that the daily net production of tropospheric ozone over the Baltimore/Washington area decreased from ∼20 ppbv day−1 in the late 1990s to ∼7 ppbv day−1 in the early 2010s during ozone season. A decrease in the long-term column ozone is observed as ∼0.2 DU yr−1 in the lowest 1500 m, corresponding to an improvement of ∼1.3 ppbv yr−1. Our aircraft measurements were conducted on days when severe ozone pollution was forecasted, and these results represent the decreasing trend in high ozone events over the past 15 yr. Back trajectory cluster analysis demonstrates that emissions of air pollutants from Ohio and Pennsylvania through Maryland influence the column abundances of downwind ozone in the lower atmosphere. The trends in air pollutants reveal the success of regulations implemented over the past decades and the importance of region-wide emission controls in the eastern United States.
Huang, M., K. W. Bowman, G. R. Carmichael, R. Bradley Pierce, H. M. Worden, M. Luo, O. R. Cooper, I. B. Pollack, T. B. Ryerson, and S. S. Brown (2013a), Impact of Southern California anthropogenic emissions on ozone pollution in the mountain states: Model analysis and observational evidence from space, Journal of Geophysical Research: Atmospheres, 118(22), 12,784–12,803, doi:10.1002/2013JD020205.
The impact of Southern California (SoCal) anthropogenic emissions on ozone (O3) in the mountain states in May 2010 is studied using the Sulfur Transport and Deposition Model. We identified two to six major transport events from SoCal to different subregions in the mountain states, with transport times of 0–2 days indicated by trajectories, time-lag correlations, and forward/adjoint sensitivities. Based on forward sensitivity analysis, the contributions from SoCal anthropogenic emissions to the monthly mean daily maximum 8 h average (MDA8) surface O3 in the mountain states decrease with distance from SoCal, and they range from <1 ppbv (in Wyoming) to 15 ppbv (in western Arizona). These contributions show medium (>0.6) to strong (>0.8) positive correlations with the modeled total surface MDA8 O3. For the most strongly affected states of Arizona and New Mexico, these contributions have median values of 3, 2, 5, and 15 ppbv when the total surface MDA8 O3 exceeded thresholds of 60, 65, 70, and 75 ppbv, respectively. Surface MDA8 O3 values in SoCal show strong nonlinear responses to varied magnitudes of perturbation (e.g., ±50% and 100%) in SoCal anthropogenic emissions and weak nonlinear responses in the mountain states. Case studies show that different scales of transport (e.g., trans-Pacific, stratospheric intrusions, and interstate) can be dynamically and chemically coupled and simultaneously affect O3 in the mountain states when the meteorological conditions are favorable. During some of these strong transport periods, the contributions of SoCal anthropogenic emissions to hourly O3 in the mountain states can exceed 20 ppbv, close to the magnitude during a summer event reported by Langford et al. (2010). Satellite observations from the Tropospheric Emission Spectrometer and the Measurements of Pollution in the Troposphere multispectral retrievals qualitatively demonstrate large and interstate scales of transport, respectively. Suggestions are made for future satellite missions to measure O3 with improved spatial coverage, temporal frequency, and near-surface sensitivity to provide better observational constraints on interstate pollution transport studies.
Huang, X., X.-X. Huang, T.-J. Wang, B.-L. Zhuang, S. Li, M. Xie, Y. Han, X.-Q. Yang, J.-N. Sun, A.-J. Ding, and C.-B. Fu (2013b), Observation and analysis of urban upper atmospheric carbon monoxide in Nanjing, China Environmental Science, 33(9), 1577–1584.
Using the continuous measurements of carbon monoxide (CO) at Urban Atmospheric Environment Observation Station (32 degree 03’20"N, 118 degree 46’32"E) of Nanjing University from January to December 2011, the concentration characteristics of CO was investigated. Backward trajectory and cluster analysis were used to isolate air masses reaching Nanjing with different chemical characteristics. The satellite data from MOPITT was used to analyze vertical distribution of CO at Nanjing. Studies revealed that the annual mean concentration of CO was (757.5 plus or minus 410.5) x 10 super(-9). CO exhibited significant diurnal variation with the peak around 8:00am and the trough around 16:00pm. Diurnal variations in four seasons were different, which was the largest in spring and the smallest in summer. As to weekly variation of CO, the highest concentration occurred on Friday. There was an obviously seasonal cycle of CO, with maximum in January and minimum in June. Backward trajectories arriving at Nanjing were divided into 6categories using HYSPLIT4model and cluster technique. The results indicated that CO level in the air masses from south of Jiangsu Province, Zhejiang Province and Shanghai City was the highest. The air masses from Siberian Plateau, fast transport to Nanjing, were the cleanest. The vertical variation of CO in summer was different from that in other three seasons at Nanjing. Compared with the ground-based observation, retrieved CO concentration near surface was significantly lower.
Inness, A., F. Baier, A. Benedetti, I. Bouarar, S. Chabrillat, H. Clark, C. Clerbaux, P. Coheur, R. J. Engelen, Q. Errera, J. Flemming, M. George, C. Granier, J. Hadji-Lazaro, V. Huijnen, D. Hurtmans, L. Jones, J. W. Kaiser, J. Kapsomenakis, K. Lefever, J. Leitao, M. Razinger, A. Richter, M. G. Schultz, A. J. Simmons, M. Suttie, O. Stein, J.-N. Thepaut, V. Thouret, M. Vrekoussis, and C. Zerefos (2013), The MACC reanalysis: an 8 yr data set of atmospheric composition, Atmos. Chem. Phys., 13(8), 4073–4109, doi:10.5194/acp-13-4073-2013.
An eight-year long reanalysis of atmospheric composition data covering the period 2003-2010 was constructed as part of the FP7-funded Monitoring Atmospheric Composition and Climate project by assimilating satellite data into a global model and data assimilation system. This reanalysis provides fields of chemically reactive gases, namely carbon monoxide, ozone, nitrogen oxides, and formaldehyde, as well as aerosols and greenhouse gases globally at a horizontal resolution of about 80 km for both the troposphere and the stratosphere. This paper describes the assimilation system for the reactive gases and presents validation results for the reactive gas analysis fields to document the data set and to give a first indication of its quality. Tropospheric CO values from the MACC reanalysis are on average 10-20% lower than routine observations from commercial aircrafts over airports through most of the troposphere, and have larger negative biases in the boundary layer at urban sites affected by air pollution, possibly due to an underestimation of CO or precursor emissions. Stratospheric ozone fields from the MACC reanalysis agree with ozonesondes and ACE-FTS data to within +/-10% in most seasons and regions. In the troposphere the reanalysis shows biases of -5% to +10% with respect to ozonesondes and aircraft data in the extratropics, but has larger negative biases in the tropics. Area-averaged total column ozone agrees with ozone fields from a multi-sensor reanalysis data set to within a few percent. NO2 fields from the reanalysis show the right seasonality over polluted urban areas of the NH and over tropical biomass burning areas, but underestimate wintertime NO2 maxima over anthropogenic pollution regions and overestimate NO2 in northern and southern Africa during the tropical biomass burning seasons. Tropospheric HCHO is well simulated in the MACC re-analysis even though no satellite data are assimilated. It shows good agreement with independent SCIAMACHY retrievals over regions dominated by biogenic emissions with some anthropogenic input, such as the eastern US and China, and also over African regions influenced by biogenic sources and biomass burning.
Jiang, Z., D. B. A. Jones, H. M. Worden, M. N. Deeter, D. K. Henze, J. Worden, K. W. Bowman, C. a. M. Brenninkmeijer, and T. J. Schuck (2013), Impact of model errors in convective transport on CO source estimates inferred from MOPITT CO retrievals, Journal of Geophysical Research: Atmospheres, 118(4), 2073–2083, doi:10.1002/jgrd.50216.
Estimates of surface fluxes of carbon monoxide (CO) inferred from remote sensing observations or free tropospheric trace gas measurements using global chemical transport models can have significant uncertainties because of discrepancies in the vertical transport in the models, which make it challenging to unequivocally relate the observations back to the surface fluxes in the models. The new Measurement of Pollution in the Troposphere (MOPITT) version 5 retrievals provide greater sensitivity to lower tropospheric CO over land relative to the previous versions and are, therefore, useful for evaluating vertical transport in models. We have assimilated the new MOPITT CO retrievals, using the Goddard Earth Observing System (GEOS)-Chem model, to study the influence of vertical transport errors on inferred CO sources. We compared the source estimates obtained by assimilating the CO profiles, the column amounts, and the surface level retrievals for June–August 2006. The three different inversions produced large differences in the source estimates in regions of convection and strong CO emissions. The inversion using the CO profiles suggested an 85% increase in emissions in India/Southeast Asia, which exacerbated the model bias in the lower and middle troposphere, whereas using the surface level retrievals produced a 37% decrease in Indian/Southeast Asian emissions, which exacerbated the underestimate of CO in the upper troposphere. Globally, the inversion with the surface retrievals suggested a 22% reduction in emissions from the a priori estimate of 161 Tg CO/month (from combustion and the oxidation of biogenic volatile organic compounds), averaged in June–August 2006. The analysis results were validated with independent surface CO measurements from NOAA Global Monitoring Division (GMD) network and upper troposphere CO measurements from the Civil Aircraft for the Regular Investigation of the Atmosphere Based on an Instrumented Container (CARIBIC). We found that the inversion with the surface retrievals agreed best with surface CO data but produced the largest discrepancy with the CARIBIC aircraft data in the upper troposphere, suggesting the influence of vertical transport errors in the model. Our results show that the comparison of the a posteriori CO distributions obtained from the inversions using the surface and profile retrievals provides a means of characterizing the potential impact of the vertical transport biases on the source estimates and the CO distribution.
Kumar, R., M. Naja, G. G. Pfister, M. C. Barth, and G. P. Brasseur (2013), Source attribution of carbon monoxide in India and surrounding regions during wintertime, Journal of Geophysical Research: Atmospheres, 118(4), 1981–1995, doi:10.1002/jgrd.50134.
This study presents a CO source contribution analysis for the atmosphere of South Asia during January–February 2008. The approach includes into the Weather Research and Forecasting Model with Chemistry 11 CO tracers, which track CO from different source types and regions. The comparison of model results with Measurement of Pollution in the Troposphere CO retrievals shows that the model reproduces the spatial, vertical, and temporal distributions of Measurement of Pollution in the Troposphere retrievals fairly well, but generally overestimates CO retrievals in the lower troposphere. CO mixing ratios averaged over the model domain at the surface, in the planetary boundary layer, and the free troposphere are estimated as 321 ± 291, 280 ± 208, and 125 ± 27 ppbv, respectively. Model results show that wintertime CO in the boundary layer and free troposphere over India is mostly due to anthropogenic emissions and to CO inflow. In the boundary layer, the contribution from anthropogenic sources dominates (40–90%), while in the free troposphere the main contribution is due to CO inflow from the lateral boundaries (50–90%). Over the Arabian Sea and the Bay of Bengal, 43–51% of surface CO mixing ratios come from the Indian subcontinent and 49–57% from regions outside of South Asia. The anthropogenic sources in the Indo-Gangetic Plain region are found to contribute, on average, 42% and 76% to anthropogenic surface CO over the Arabian Sea and the Bay of Bengal, respectively. The anthropogenic emissions from western and southern India contribute 49% to anthropogenic surface CO over the Arabian Sea. Anthropogenic emissions contribute only up to 40% over Burma where biomass burning plays a more important role. Regional transport contributes significantly to total anthropogenic CO over southern India (41%), Burma (49%), and even exceeds the contribution from local sources in western India (58%).
Lalitaporn, P., G. Kurata, Y. Matsuoka, N. Thongboonchoo, and V. Surapipith (2013), Long-term analysis of NO2, CO, and AOD seasonal variability using satellite observations over Asia and intercomparison with emission inventories and model, Air Qual Atmos Health, 6(4), 655–672, doi:10.1007/s11869-013-0205-z.
Long-term analysis of tropospheric nitrogen dioxide (NO2) columns retrieved from GOME, SCIAMACHY, OMI and GOME-2 satellites, carbon monoxide (CO) columns from MOPITT satellite, and aerosol optical depths (AODs) from MODIS satellite was performed for Southeast Asian countries including Japan and China during 1996–2012. The results show that significant increasing levels of tropospheric NO2 columns can be clearly observed during the study period, especially above the eastern regions of China. The cities located in different latitude zones present the seasonal cycle of NO2 columns, CO columns, and AODs differently. For the cities located around mid-latitude zone, the maximum levels of NO2 and CO columns can be observed in the winter (November–March) and the minimum in the summer (June–September). On the contrary, the maximum levels for the cities near Equator zone are revealed in dry season (June–October). In the case of AODs, the maximum peaks normally occur during biomass burning season. Ground monitoring concentrations of NO2, CO, and PM10 were also comparably analyzed with satellite NO2 columns, CO columns, and AODs, respectively. Anthropogenic and biomass burning emissions were derived to investigate the consistency with satellite retrievals. The results show that satellite observations are able to capture the trend and seasonal variability of the emissions and ground concentrations. The model simulations were conducted using CMAQ model. Generally, simulated model results agree well with those retrieved from satellite measurements for spatial distribution and seasonal pattern. However, the modeled results underestimate satellite data probably due to the inaccuracy in emission inventories, the inaccuracy of spatial and temporal allocations, and the uncertainties in the satellite retrievals.
van Leeuwen, T. T., W. Peters, M. C. Krol, and G. R. van der Werf (2013), Dynamic biomass burning emission factors and their impact on atmospheric CO mixing ratios, Journal of Geophysical Research: Atmospheres, n/a–n/a, doi:10.1002/jgrd.50478.
Biomass burning is a major source of trace gases and aerosols, influencing atmospheric chemistry and climate. To quantitatively assess its impact, an accurate representation of fire emissions is crucial for the atmospheric modeling community. So far, most studies rely on static emission factors (EF) which convert estimates of dry matter burned to trace gas and aerosol emissions. These EFs are often based on the arithmetic mean of field measurements stratified by biome, neglecting the variability in time and space. Here we present global carbon monoxide (CO) emission estimates from fires based on six EF scenarios with different spatial and temporal variability, using dry matter emission estimates from the Global Fire Emissions Database (GFED). We used the TM5 model to transport these different bottom-up estimates in the atmosphere and found that including spatial and temporal variability in EFs impacted CO mixing ratios substantially. Most scenarios estimated higher CO mixing ratios (up to 40% more CO from fires during the burning season) over boreal regions compared to the GFED standard run, while a decrease ( 15%) was estimated over the continent of Africa. A comparison to atmospheric CO observations showed differences of 10–20 ppb between the scenarios and systematic deviations from local observations. Although temporal correlations of specific EF scenarios improved for certain regions, an overall “best” set of EFs could not be selected. Our results provide a new set of emission estimates that can be used for sensitivity analyses and highlight the importance of better understanding spatial and temporal variability in EFs for atmospheric studies in general and specifically when using CO or aerosols concentration measurements to top-down constrain fire carbon emissions.
Lin, Y. C., C. Y. Lin, P. H. Lin, G. Engling, Y. C. Lin, Y. Y. Lan, C. W. June Chang, T. H. Kuo, W. T. Hsu, and C. C. Ting (2013), Influence of Southeast Asian biomass burning on ozone and carbon monoxide over subtropical Taiwan, Atmospheric Environment, 64, 358–365, doi:10.1016/j.atmosenv.2012.09.050.
Surface ozone (O3) and carbon monoxide (CO) mixing ratios were measured at Mei-Feng (24.05 °N, 120.10 °E, 2269 m above sea level) remote mountain site between March 2009 and September 2010 to investigate the impact of regional pollution on O3 and CO. The results showed that the maximum values of both O3 and CO were found in the springtime. Backward trajectory analysis, combined with MODIS fire spots suggested that the enhanced O3 and CO in springtime could be attributed to biomass burning (BB) activities over Southeast (SE) Asia. Thirteen BB events were identified by backward trajectory analysis, MODIS fires, NCEP weather data sets and CO concentrations. Good correlation between O3 and CO was found during the BB plumes. Using the linear regression, the slope (ΔO3/ΔCO) was calculated to be 0.18 ± 0.08 (mean ± 1σ). This value was in agreement with that of 0.2 observed over the west Pacific region during the TRACE-P campaign, but was higher than those (0.11–0.14) of Canadian and Siberian fires. Moreover, significant enhanced O3 productivity was also found in aged BB plumes and that mixed with urban emissions from SE coastal China. To assess the net influence of SE Asian BB, the air masses from SE Asia and SE China were divided in two groups: those that passed over the fire regions (PF) and those that did not (NP). The result showed that the maximum differences between PF and NP were estimated in March with 8 ppb for O3 and 45 ppb for CO, respectively, accounting for 23% of both CO and O3 levels at Mei-Feng. Although uncertainties existed in the estimations, the significant discrepancies of O3 and CO in the two air groups suggested the air pollutants emitted by SE Asian BB could be transported and influence the air quality over subtropical Taiwan in springtime.
Liu, C., S. Beirle, T. Butler, P. Hoor, C. Frankenberg, P. Jöckel, M. Penning de Vries, U. Platt, A. Pozzer, M. G. Lawrence, J. Lelieveld, H. Tost, and T. Wagner (2013), CO profiles from SCIAMACHY observations using cloud slicing and comparison with model simulations, Atmospheric Chemistry and Physics Discussions, 13(5), 11659–11688, doi:10.5194/acpd-13-11659-2013.
We apply a cloud slicing technique (CST), originally developed for Total Ozone Mapping Spectrometer (TOMS) ozone observations, to CO vertical column densities retrieved from the SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY). CST makes use of the shielding effect of clouds and combines trace gas column measurements of cloudy pixels with different cloud heights to retrieve fractional columns aloft. Here we determine seasonal mean tropospheric CO profiles at a vertical resolution of 1 km, which is much finer than what can be obtained from thermal IR instruments. However, since both the atmospheric CO profiles and the effective cloud heights depend systematically on meteorology, the profiles retrieved from the CST have to be interpreted with care. We compare the seasonal mean SCIAMACHY CO profiles with the output from two atmospheric models sampled in the same way as the satellite observations. We find systematic differences both in the absolute values and vertical and horizontal gradients. The results indicate that vertical (re)distributions of emissions and their strengths are not well represented in the models. It seems likely that deep convective transport is underestimated.
Mallik, C., S. Lal, S. Venkataramani, M. Naja, and N. Ojha (2013), Variability in ozone and its precursors over the Bay of Bengal during post monsoon: Transport and emission effects, Journal of Geophysical Research: Atmospheres, 118(17), 10,190–10,209, doi:10.1002/jgrd.50764.
Simultaneous measurements of O3, CO, NOx, CH4, and light nonmethane hydrocarbons were made over the Bay of Bengal (BoB) during 28 October to 17 November 2010 to study the role of chemistry and dynamics. The measurements revealed large variability in O3 (11 to 60 ppbv) and CO (45 to 260 ppbv). Estimated south to north latitudinal gradients in O3 (3.95 ppbv/°) and CO (16.56 ppbv/°) were significantly higher than those observed during earlier campaigns. Hybrid Single-Particle Lagrangian Integrated Trajectory simulated back air trajectories were used to classify these measurements into pollution plumes from nearby sources (India-Bangladesh region and Southeast Asia), influenced by long-range transport and pristine marine air from the Indian Ocean. Interspecies correlations were used to identify emission signatures in these air masses, e.g., chemical proxies suggested influence of biofuel/biomass burning in NE-BoB and E-BoB air masses. Principle component analysis indicated contributions of ship emissions to NOx levels over the BoB. Influences of fire from the Myanmar and Thailand regions are shown to be the potential contributor to enhanced CO levels (>250 ppbv) over the BoB during 14–15 November. Diurnal variations in surface O3 revealed effects of advection, entrainment, and photochemistry. A chemical box model simulated the photochemical buildup in O3 in polluted air masses and daytime destruction in pristine oceanic air masses.
Miyazaki, K., and H. Eskes (2013), Constraints on surface NOx emissions by assimilating satellite observations of multiple species, Geophysical Research Letters, 40(17), 4745–4750, doi:10.1002/grl.50894.
Surface NOx emissions are estimated by a combined assimilation of satellite observations of NO2, CO, O3, and HNO3 with a global chemical transport model. The assimilation of measurements for species other than NO2 provides additional constraints on the NOx emissions by adjusting the concentrations of the species affecting the NOx chemistry and leads to changes in the regional monthly-mean emissions of −58 to +32% and the annual total emissions of −16 to +3%. These large changes highlight that uncertainties in the model chemistry impact the quality of the emission estimates. In the inversion from NO2 observations only, NOx analysis increments occur closer to the surface. Because of the shorter residence time, larger emissions increments are required compared to the multiple species assimilation. Validation against independent observations and comparisons with the recent Regional Emission inventory in Asia version 2.1 emissions shows that the multiple species assimilation improves the chemical consistency including the relation between concentrations and the estimated emissions.
Naik, V., A. Voulgarakis, A. M. Fiore, L. W. Horowitz, J.-F. Lamarque, M. Lin, M. J. Prather, P. J. Young, D. Bergmann, P. J. Cameron-Smith, I. Cionni, W. J. Collins, S. B. Dalsøren, R. Doherty, V. Eyring, G. Faluvegi, G. A. Folberth, B. Josse, Y. H. Lee, I. A. MacKenzie, T. Nagashima, T. P. C. van Noije, D. A. Plummer, M. Righi, S. T. Rumbold, R. Skeie, D. T. Shindell, D. S. Stevenson, S. Strode, K. Sudo, S. Szopa, and G. Zeng (2013), Preindustrial to present-day changes in tropospheric hydroxyl radical and methane lifetime from the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), Atmos. Chem. Phys., 13(10), 5277–5298, doi:10.5194/acp-13-5277-2013.
We have analysed time-slice simulations from 17 global models, participating in the Atmospheric Chemistry and Climate Model Intercomparison Project (ACCMIP), to explore changes in present-day (2000) hydroxyl radical (OH) concentration and methane (CH4) lifetime relative to preindustrial times (1850) and to 1980. A comparison of modeled and observation-derived methane and methyl chloroform lifetimes suggests that the present-day global multimodel mean OH concentration is overestimated by 5 to 10% but is within the range of uncertainties. The models consistently simulate higher OH concentrations in the Northern Hemisphere (NH) compared with the Southern Hemisphere (SH) for the present-day (2000; inter-hemispheric ratios of 1.13 to 1.42), in contrast to observation-based approaches which generally indicate higher OH in the SH although uncertainties are large. Evaluation of simulated carbon monoxide (CO) concentrations, the primary sink for OH, against ground-based and satellite observations suggests low biases in the NH that may contribute to the high north–south OH asymmetry in the models. The models vary widely in their regional distribution of present-day OH concentrations (up to 34 %). Despite large regional changes, the multi-model global mean (mass-weighted) OH concentration changes little over the past 150 yr, due to concurrent increases in factors that enhance OH (humidity, tropospheric ozone, nitrogen oxide (NOx) emissions, and UV radiation due to decreases in stratospheric ozone), compensated by increases in OH sinks (methane abundance, carbon monoxide and non-methane volatile organic carbon (NMVOC) emissions). The large inter-model diversity in the sign and magnitude of preindustrial to present-day OH changes (ranging from a decrease of 12.7% to an increase of 14.6 %) indicate that uncertainty remains in our understanding of the long-term trends in OH and methane lifetime. We show that this diversity is largely explained by the different ratio of the change in global mean tropospheric CO and NOx burdens (1CO/1NOx, approximately represents changes in OH sinks versus changes in OH sources) in the models, pointing to a need for better constraints on natural precursor emissions and on the chemical mechanisms in the current generation of chemistry-climate models. For the 1980 to 2000 period, we find that climate warming and a slight increase in mean OH (3.5±2.2 %) leads to a 4.3±1.9% decrease in the methane lifetime. Analysing sensitivity simulations performed by 10 models, we find that preindustrial to presentday climate change decreased the methane lifetime by about four months, representing a negative feedback on the climate system. Further, we analysed attribution experiments performed by a subset of models relative to 2000 conditions with only one precursor at a time set to 1860 levels. We find that global mean OH increased by 46.4±12.2% in response to preindustrial to present-day anthropogenic NOx emission increases, and decreased by 17.3±2.3 %, 7.6±1.5 %, and 3.1±3.0% due to methane burden, and anthropogenic CO, and NMVOC emissions increases, respectively.
Nair, P. R., L. M. David, S. Aryasree, and K. Susan George (2013), Distribution of ozone in the marine boundary layer of Arabian Sea prior to monsoon: Prevailing airmass and effect of aerosols, Atmospheric Environment, 74, 18–28, doi:10.1016/j.atmosenv.2013.02.049.
Surface ozone (O3) measurements were carried out in the marine environment of the Arabian Sea (AS) during the premonsoon months, April–May 2006, as part of the Integrated Campaign for Aerosols, gases and Radiation Budget. The O3 mixing ratio over the AS varied in the range ∼3–22 ppb with a mean of 13.5 ± 2 ppb. Comparatively high mixing ratios were observed over the southern AS and close to the coast. The spatial pattern did not show any evidence of transport from nearby landmass or in situ photochemistry. Longitudinally separated narrow regions of low and high O3 were seen over the southern AS. The role of aerosols in modifying the O3 concentration was examined based on the co-located measurement of aerosol mass loading, number density, size distribution and optical depth. The O3 mixing ratio showed positive correlation with aerosol loading. Over high O3 regions, large particle concentration showed significant enhancement. The role of chloride ion in depleting O3 was also investigated. The observed spatial features were compared with those measured during the earlier cruises conducted in different seasons and over various oceanic regions. A comparison has been made with the measurements over the Bay of Bengal during the same cruise.
Park, K., L. K. Emmons, Z. Wang, and J. E. Mak (2013), Large interannual variations in nonmethane volatile organic compound emissions based on measurements of carbon monoxide, Geophysical Research Letters, 40(1), 221–226, doi:10.1029/2012GL052303.
We present source estimates of atmospheric carbon monoxide from nonmethane volatile organic compound (NMVOC) oxidation during a period of 8 years (1997–2004) using a Bayesian inversion analysis. The optimized global NMVOC-derived CO source strength indicates a change of a factor of 2 between the 1997–1998 strong El Niño and subsequent La Niña conditions. For comparison, the average 8 year interannual variability (IAV) is 18%. The variation of NMVOC-derived CO is closely correlated with the Oceanic Niño Index (ONI) and surface temperature. A time-lagged correlation analysis between ONI and NMVOC-derived CO inventory indicated El Niño/Southern Oscillation leads the Northern Hemisphere (NH) NMVOC-derived CO production by about 3 months earlier than the Southern Hemisphere’s (SH). The SH NMVOC-derived CO was positively correlated with the lagged-ONI (r = 0.57), while the temperature change barely influenced SH NMVOC-derived CO (r = 0.01). In the NH, temperature was more robustly correlated with NMVOC-derived CO (r = 0.58) than the lagged-ONI (r = 0.35). In particular, the extra-tropical temperature showed a strong correlation (r = 0.90) with the NH NMVOC-derived CO and suggested its primary role in controlling the interannual variability of the NH NMVOC-derived CO.
Pechony, O., D. T. Shindell, and G. Faluvegi (2013), Direct top-down estimates of biomass burning CO emissions using TES and MOPITT versus bottom-up GFED inventory, Journal of Geophysical Research: Atmospheres, n/a–n/a, doi:10.1002/jgrd.50624.
In this study, we utilize near-simultaneous observations from two sets of multiple satellite sensors to segregate Tropospheric Emission Spectrometer (TES) and Measurements of Pollution in the Troposphere (MOPITT) CO observations over active fire sources from those made over clear background. Hence, we obtain direct estimates of biomass burning CO emissions without invoking inverse modeling as in traditional top-down methods. We find considerable differences between Global Fire Emissions Database (GFED) versions 2.1 and 3.1 and satellite-based emission estimates in many regions. Both inventories appear to greatly underestimate South and Southeast Asia emissions, for example. On global scales, however, CO emissions in both inventories and in the MOPITT-based analysis agree reasonably well, with the largest bias (30%) found in the Northern Hemisphere spring. In the Southern Hemisphere, there is a one-month shift between the GFED and MOPITT-based fire emissions peak. Afternoon tropical fire emissions retrieved from TES are about two times higher than the morning MOPITT retrievals. This appears to be both a real difference due to the diurnal fire activity variations, and a bias due to the scarcity of TES data.
Pommier, M., C. A. McLinden, and M. Deeter (2013), Relative changes in CO emissions over megacities based on observations from space, Geophysical Research Letters, 40(14), 3766–3771, doi:10.1002/grl.50704.
Urban areas are large sources of several air pollutants, with carbon monoxide (CO) among the largest. Yet measurement from space of their CO emissions remains elusive due to its long lifetime. Here we introduce a new method of estimating relative changes in CO emissions over megacities. A new multichannel Measurements of Pollution in the Troposphere (MOPITT) CO data product, offering improved sensitivity to the boundary layer, is used to estimate this relative change over eight megacities: Moscow, Paris, Mexico, Tehran, Baghdad, Los Angeles, Sao Paulo, and Delhi. By combining MOPITT observations with wind information from a meteorological reanalysis, changes in the CO upwind-downwind difference are used as a proxy for changes in emissions. Most locations show a clear reduction in CO emission between 2000–2003 and 2004–2008, reaching −43% over Tehran and −47% over Baghdad. There is a contrasted agreement between these results and the MACCity and Emission Database for Global Atmospheric Research v4.2 inventories.
R’Honi, Y., L. Clarisse, C. Clerbaux, D. Hurtmans, V. Duflot, S. Turquety, Y. Ngadi, and P.-F. Coheur (2013), Exceptional emissions of NH3 and HCOOH in the 2010 Russian wildfires, Atmos. Chem. Phys., 13(8), 4171–4181, doi:10.5194/acp-13-4171-2013.
In July 2010, several hundred forest and peat fires broke out across central Russia during its hottest summer on record. Here, we analyze these wildfires using observations of the Infrared Atmospheric Sounding Interferometer (IASI). Carbon monoxide (CO), ammonia (NH3) and formic acid (HCOOH) total columns are presented for the year 2010. Maximum total columns were found to be one order (for CO and HCOOH) and two orders (for NH3) of magnitude larger than typical background values. The temporal evolution of NH3 and HCOOH enhancement ratios relative to CO are presented. Evidence of secondary formation of HCOOH is found, with enhancement ratios exceeding reported emission ratios in fresh plumes. We estimate the total emitted masses for the period July–August 2010 over the center of western Russia; they are 19–33 Tg (CO), 0.7–2.6 Tg (NH3) and 0.9–3.9 Tg (HCOOH). For NH3 and HCOOH, these quantities are comparable to what is emitted in the course of a whole year by all extratropical forest fires.
Sahu, L. K., V. Sheel, M. Kajino, S. S. Gunthe, V. Thouret, P. Nedelec, and H. G. Smit (2013), Characteristics of tropospheric ozone variability over an urban site in Southeast Asia: A study based on MOZAIC and MOZART vertical profiles, Journal of Geophysical Research: Atmospheres, 118(15), 8729–8747, doi:10.1002/jgrd.50662.
The Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) profiles of O3 and CO were analyzed to study their variation in the troposphere over Bangkok. Mixing ratios of O3 and CO were enhanced in planetary boundary layer (PBL) being highest in winter followed by summer and wet seasons. The daytime profiles of O3 show higher values compared to nighttime observations in PBL region, but little differences were observed in the free troposphere. The decreasing mixing ratios of O3 in the lower and upper troposphere were associated with shallow and deep convections, respectively. Back trajectory and fire count data indicate that the seasonal variations in trace gases were caused mainly by the regional shift in long-range transport and biomass-burning patterns. In wet season, flow of oceanic air and negligible presence of local biomass burning resulted in lowest O3 and CO, while their high levels in dry season were due to extensive biomass burning and transport of continental air masses. The Model for Ozone and Related Chemical Tracers (MOZART) underestimated both O3 and CO in the PBL region but overestimated these in the free troposphere. Simulations of O3 and CO also show the daytime/nighttime differences but do not capture several key features observed in the vertical distributions. The observed and simulated values of O3 and CO during September–November 2006 were significantly higher than the same period of 2005. The year-to-year differences were mainly due to El Niño-led extensive fires in Indonesia during 2006 but normal condition during 2005.
Shim, C., J. Lee, and Y. Wang (2013), Effect of continental sources and sinks on the seasonal and latitudinal gradient of atmospheric carbon dioxide over East Asia, Atmospheric Environment, 79, 853–860, doi:10.1016/j.atmosenv.2013.07.055.
Abstract Here we demonstrate the sharp seasonal and latitudinal gradient of atmospheric CO2 over East Asia, where there are relatively few ground-based observations. The Greenhouse gases Observing SATellite (GOSAT) column-averaged dry air CO2 mole fraction (xCO2) retrieved by NASA’s Atmospheric CO2 Observations from Space (ACOS) (2009–2011) program and GEOS-Chem nested-grid CO2 results are used. The strong anthropogenic emissions mainly from China and intensive vegetation uptake from northeastern Asia lead to a clear seasonal change of the xCO2 between spring maximum and summer minimum (&gt;10 ppm). In particular, the steep latitudinal gradient of summer time xCO2 by 3–5 ppm in the vicinity of the Korean Peninsula (32°N-44°N) is likely attributed to the large difference in CO2 fluxes among industry/cities, northeastern forests and the northwest Pacific region. This study represents the current progress to understand sub-continental scale atmospheric CO2 variabilities with recent satellite retrievals and nested-grid modeling.
Shindell, D. T., O. Pechony, A. Voulgarakis, G. Faluvegi, L. Nazarenko, J.-F. Lamarque, K. Bowman, G. Milly, B. Kovari, R. Ruedy, and G. A. Schmidt (2013), Interactive ozone and methane chemistry in GISS-E2 historical and future climate simulations, Atmos. Chem. Phys., 13(5), 2653–2689, doi:10.5194/acp-13-2653-2013.
Changes in climate and emissions will affect future air quality. In this work, simulations of regional air quality during current (2001–2005) and future (2026–2030) winter and summer are conducted with the newly released CMAQ version 5.0 to examine the impacts of simulated future climate and anthropogenic emission projections on air quality over the U.S. Current meteorological and chemical predictions are evaluated against observations to assess the model’s capability in reproducing the seasonal differences. WRF and CMAQ capture the overall observational spatial patterns and seasonal differences. Biases in model predictions are attributed to uncertainties in emissions, boundary conditions, and limitations in model physical and chemical treatments as well as the use of a coarse grid resolution. Increased temperatures (up to 3.18 °C) and decreased ventilation (up to 157 m in planetary boundary layer height) are found in both future winter and summer, with more prominent changes in winter. Increases in future temperatures result in increased isoprene and terpene emissions in winter and summer, driving the increase in maximum 8-h average O3 (up to 5.0 ppb) over the eastern U.S. in winter while decreases in NOx emissions drive the decrease in O3 over most of the U.S. in summer. Future PM2.5 concentrations in winter and summer and many of its components decrease due to decreases in primary anthropogenic emissions and the concentrations of secondary anthropogenic pollutants as well as increased precipitation in winter. Future winter and summer dry and wet deposition fluxes are spatially variable and increase with decreasing surface resistance and precipitation, respectively. They decrease with a decrease in ambient particulate concentrations. Anthropogenic emissions play a more important role in summer than in winter for future O3 and PM2.5 levels, with a dominance of the effects of significant emission reductions over those of climate change on future PM2.5 levels.
Silva, S. J., A. F. Arellano, and H. M. Worden (2013), Toward anthropogenic combustion emission constraints from space-based analysis of urban CO2/CO sensitivity, Geophysical Research Letters, 40(18), 4971–4976, doi:10.1002/grl.50954.
We explore the value of multispectral CO retrievals from NASA/Terra Measurement of Pollution In The Troposphere (MOPITT v5), along with Atmospheric CO2 Observations from Space (ACOSv2.9) CO2 retrievals from the Japan Aerospace Exploration Agency Greenhouse Gases Observing Satellite (GOSAT), for characterizing emissions from anthropogenic combustion. We use these satellite retrievals to analyze observed CO2/CO enhancement ratios (ΔCO2/ΔCO) over megacities. Since CO is coemitted with CO2 in anthropogenic combustion, the observed ΔCO2/ΔCO characterizes the general trend in combustion activity. Our analyses show patterns in ΔCO2/ΔCO that correspond well with the developed/developing status of megacities, and ΔCO2/ΔCO that agree well with available literature and emission inventories to approximately 20%. Comparisons with ΔCO2/ΔCO derived from Total Carbon Column Observing Network measurements show similar agreement, where some of the differences in observed ΔCO2/ΔCO are due to representativeness and limited GOSAT data. Our results imply potential constraints in anthropogenic combustion from GOSAT/MOPITT, particularly in augmenting our carbon monitoring systems.
Sitnov, S. A., and I. I. Mokhov (2013), Water-vapor content in the atmosphere over European Russia during the summer 2010 fires, Izv. Atmos. Ocean. Phys., 49(4), 380–394, doi:10.1134/S0001433813040099.
We study the water vapor (WV) content over European Russia (ER) during the period of forest and peatbog fires in July–August 2010 using total column water vapor observations from MODIS instruments (both Aqua and Terra platforms) as well as aerological data and NCEP/NCAR reanalysis. It is found that the spatial distribution of total column water vapor (TCWV) over ER in this period was anomalous, with the WV excess in the north of the territory and its deficit in the south of ER. The relationship between WV variations, atmospheric dynamics and the fire situation is analyzed. Along with the processes of the WV advection and evaporation we evaluate the contribution of pyrogenic emission of WV in spatial-temporal evolution of WV over ER during wildfires. The changes of water vapor at different heights in the troposphere and stratosphere are investigated. The results of a comparative analysis of WV contents during the periods of summertime atmospheric blockings in 1972 and 2010 are also presented. The near-infrared total-column precipitable water MODIS products (L3) are validated by upper-air radiosonde data.
Srivastava, S., and V. Sheel (2013), Study of tropospheric CO and O3 enhancement episode over Indonesia during Autumn 2006 using the Model for Ozone and Related chemical Tracers (MOZART-4), Atmospheric Environment, 67, 53–62, doi:10.1016/j.atmosenv.2012.09.067.
An intense biomass burning event occurred over Indonesia in Autumn of 2006. We study the impact of this event on the free tropospheric abundances of carbon monoxide (CO) and ozone (O3) using MOPITT (Measurements of Pollution In The Troposphere) observations, ozonesonde measurements and 3D chemistry transport model MOZART (Model for Ozone and Related chemical Tracers). MOPITT observations showed an episode of enhanced CO in the free troposphere over the Indonesian region during October–November 2006. This feature is reproduced well by MOZART. The model mass diagnostics identifies the source of enhanced CO mixing ratio in the free troposphere (100–250 ppbv) as due to convective processes. The implication of the fire plume on the vertical distribution of O3 over Kuala Lumpur has been studied. The tropospheric O3 increased over this location by 10–25 ppbv during Autumn 2006 as compared to Autumn 2005 and 2007. The MOZART model simulation significantly underestimated this tropospheric O3 enhancement. The model is run both with and without Indonesian biomass burning emissions to estimate the contribution of fire emission in CO and O3 enhancement. Biomass burning emission is found to be responsible for an average increase in CO by 104 ± 56 ppbv and O3 by 5 ± 1 ppbv from surface to 100 hPa range. The model results also showed that biomass burning and El Niño related dynamical changes both contributed (∼4 ppbv–12 ppbv) to the observed increase in tropospheric O3 over the Indonesian region during Autumn 2006.
Streets, D. G., T. Canty, G. R. Carmichael, B. de Foy, R. R. Dickerson, B. N. Duncan, D. P. Edwards, J. A. Haynes, D. K. Henze, M. R. Houyoux, D. J. Jacob, N. A. Krotkov, L. N. Lamsal, Y. Liu, Z. Lu, R. V. Martin, G. G. Pfister, R. W. Pinder, R. J. Salawitch, and K. J. Wecht (2013), Emissions estimation from satellite retrievals: A review of current capability, Atmospheric Environment, 77, 1011–1042, doi:10.1016/j.atmosenv.2013.05.051.
Abstract Since the mid-1990s a new generation of Earth-observing satellites has been able to detect tropospheric air pollution at increasingly high spatial and temporal resolution. Most primary emitted species can be measured by one or more of the instruments. This review article addresses the question of how well we can relate the satellite measurements to quantification of primary emissions and what advances are needed to improve the usability of the measurements by U.S. air quality managers. Built on a comprehensive literature review and comprising input by both satellite experts and emission inventory specialists, the review identifies several targets that seem promising: large point sources of NOx and SO2, species that are difficult to measure by other means (NH3 and CH4, for example), area sources that cannot easily be quantified by traditional bottom-up methods (such as unconventional oil and gas extraction, shipping, biomass burning, and biogenic sources), and the temporal variation of emissions (seasonal, diurnal, episodic). Techniques that enhance the usefulness of current retrievals (data assimilation, oversampling, multi-species retrievals, improved vertical profiles, etc.) are discussed. Finally, we point out the value of having new geostationary satellites like GEO-CAPE and TEMPO over North America that could provide measurements at high spatial (few km) and temporal (hourly) resolution.
Strode, S. A., and S. Pawson (2013), Detection of carbon monoxide trends in the presence of interannual variability, Journal of Geophysical Research: Atmospheres, 118(21), 12,257–12,273, doi:10.1002/2013JD020258.
Trends in fossil fuel emissions are a major driver of changes in atmospheric CO, but detection of trends in CO from anthropogenic sources is complicated by the presence of large interannual variability (IAV) in biomass burning. We use a multiyear model simulation of CO with year-specific biomass burning to predict the number of years needed to detect the impact of changes in Asian anthropogenic emissions on downwind regions. Our study includes two cases for changing anthropogenic emissions: a stepwise change of 15% and a linear trend of 3% yr−1. We first examine how well the model reproduces the observed IAV of CO over the North Pacific, since this variability impacts the time needed to detect significant anthropogenic trends. The modeled IAV over the North Pacific correlates well with that seen from the Measurements of Pollution in the Troposphere (MOPITT) instrument but underestimates the magnitude of the variability. The model predicts that a 3% yr−1 trend in Asian anthropogenic emissions would lead to a statistically significant trend in CO surface concentration in the western United States within 12 years, and accounting for Siberian boreal biomass-burning emissions greatly reduces the number of years needed for trend detection. Combining the modeled trend with the observed MOPITT variability at 500 hPa, we estimate that the 3% yr−1 trend could be detectable in satellite observations over Asia in approximately a decade. Our predicted timescales for trend detection highlight the importance of long-term measurements of CO from satellites.
Uno, I., K. Yumimoto, T. Ohara, and J.-I. Kurokawa (2013a), Analysis of long-term variation in CO concentration and emission source contribution based on a tagged transport model, Journal of Japan Society for Atmospheric Environment/Taiki Kankyo Gakkaishi, 48(3), 133–139, doi:http://dx.doi.org/10.11298/taiki.48.133.
We studied Asian scale CO source-receptor (S-R) relationship from 2004-2011 based on the tagged CO tracer model. GEOS Chem (Version 9-1-1) was used with a high-resolution Asian domain (0.5[ring] x 0.667[ring] resolution) which was 1-way nested into the global domain. Ten tagged regions were set within the Asian region. The REAS2.0 emission inventory was used as the Asian anthropogenic emission. The model results were compared with 6 ground base station and MOPITT satellite retrieval data. The model results showed clear year-by-year variations, and showed a reasonable agreement with the observations. For the observation sites within the Asian domain, the impact from the Chinese CO emission was dominant and we successfully summarized the relationship between the CO emission from the tagged regions and corresponding CO contribution from each receptor site. It was found that the long-term CO variations were controlled both from Asian and global emission source changes, and also significantly by the year-to-year meteorological conditions (outflow efficiency from China). We also showed that the contribution from non-Asian emissions was also especially important in the springtime that was underestimated by the model simulation.
Uno, I., K. Yumimoto, T. Ohara, and J.-I. Kurokawa (2013b), Asian Scale Source-Receptor Analysis based on Tagged CO Transport Model, Journal of Japan Society for Atmospheric Environment/Taiki Kankyo Gakkaishi, 48(3), 123–132, doi:http://dx.doi.org/10.11298/taiki.48.123.
We studied Asian scale source-receptor (S-R) relationship based on the tagged CO tracer model. GEOS Chem (Version 9-1-1) was used with a high-resolution Asian domain (0.5[ring] x .667[ring] resolution) 1-way nested to the global domain. A ten-tagged region was set in the Asian region. The model results showed a good agreement with the surface CO measurements (Yonaguni (YON), Ryori (RYO) and Minami-Torishima (MNM)) and the MOPITT satellite CO measurement. Intermittent CO peaks were well simulated during the winter to spring seasons both at YON and RYO, and its daily averaged concentration ranged from 200 - 300 ppbv. Numerical model also showed low summertime CO concentration below 100 ppbv. The annual averaged CO concentration over the Central-East China (CEC) region reached 500 ppbv. A S-R analysis showed that more than 80 % of the CO was coming from Chinese domestic emissions in that region. The fraction of CO due to the Chinese emission was 50% over the Korea and 35 - 40 % over the Japan region. An analysis of the seasonal variation indicated that the CO originated from China mainly dominated in the winter-spring seasons, while the non-Asian source and natural VOC origin CO showed a relatively high fraction in the summer season.
Vadrevu, K. P., L. Giglio, and C. Justice (2013), Satellite based analysis of fire–carbon monoxide relationships from forest and agricultural residue burning (2003–2011), Atmospheric Environment, 64, 179–191, doi:10.1016/j.atmosenv.2012.09.055.
Carbon monoxide (CO) is an important greenhouse gas that is emitted during the incomplete combustion of biomass burning. In this study, we assessed the Measurements Of Pollution In the Troposphere (MOPITT) CO retrievals from two different biomass burning regions, fires in the evergreen forests of Northeast India and agriculture residue fires, Punjab, India. We analyzed long-term trends (2003–2011) in CO retrievals and fire–CO relationships including CO profiles at nine different atmospheric levels. Over a ten year period, the mean monthly CO for Northeast India ranged from 140.86 ppmv (−1σ) to 348.85 ppbv (+1σ) with a mean CO of 244.85 ppbv. We observed a clear increase in CO signal from February to March followed by a decrease in May coinciding with the fire signal. In Punjab, the mean monthly CO ranged from 158.21 ppbv (−1σ) to 286.40 ppbv (+1σ) with a mean CO of 222.30 ppbv. Comparison of mean CO during the peak fire months suggested relatively higher CO (439.06 ppbv) during March (evergreen forest burning) than October (194.83 ppbv) agricultural residue burning. We found MODIS fire radiative power (FRP) as a stronger predictor of surface CO signal than the fire counts in the evergreen forest fires. The segmented regression model fitted using nine years of FRP–CO data was useful in finding the FRP threshold impact on CO concentrations in the evergreen forests. To explain the low correlation between fires and MOPITT CO signal from the agricultural residue fires, we used the CALIPSO data to infer the smoke plume heights. Results suggested an average smoke plume height of 2.2 km during the peak biomass burning month from agricultural fires, compared to 4.61 km from evergreen forest fires. Overall, the MODIS FRP and CALIPSO data were useful in understanding the MOPITT CO sensitivity to fires.
Worden, H. M., D. P. Edwards, M. N. Deeter, D. Fu, S. S. Kulawik, J. R. Worden, and A. Arellano (2013a), Averaging kernel prediction from atmospheric and surface state parameters based on multiple regression for nadir-viewing satellite measurements of carbon monoxide and ozone, Atmos. Meas. Tech., 6(7), 1633–1646, doi:10.5194/amt-6-1633-2013.
A current obstacle to the observation system simulation experiments (OSSEs) used to quantify the potential performance of future atmospheric composition remote sensing systems is a computationally efficient method to define the scene-dependent vertical sensitivity of measurements as expressed by the retrieval averaging kernels (AKs). We present a method for the efficient prediction of AKs for multispectral retrievals of carbon monoxide (CO) and ozone (O-3) based on actual retrievals from MOPITT (Measurements Of Pollution In The Troposphere) on the Earth Observing System (EOS)-Terra satellite and TES (Tropospheric Emission Spectrometer) and OMI (Ozone Monitoring Instrument) on EOS-Aura, respectively. This employs a multiple regression approach for deriving scene-dependent AKs using predictors based on state parameters such as the thermal contrast between the surface and lower atmospheric layers, trace gas volume mixing ratios (VMRs), solar zenith angle, water vapor amount, etc. We first compute the singular value decomposition (SVD) for individual cloud-free AKs and retain the first three ranked singular vectors in order to fit the most significant orthogonal components of the AK in the subsequent multiple regression on a training set of retrieval cases. The resulting fit coefficients are applied to the predictors from a different test set of test retrievals cased to reconstruct predicted AKs, which can then be evaluated against the true retrieval AKs from the test set. By comparing the VMR profile adjustment resulting from the use of the predicted vs. true AKs, we quantify the CO and O-3 VMR profile errors associated with the use of the predicted AKs compared to the true AKs that might be obtained from a computationally expensive full retrieval calculation as part of an OSSE. Similarly, we estimate the errors in CO and O-3 VMRs from using a single regional average AK to represent all retrievals, which has been a common approximation in chemical OSSEs performed to date. For both CO and O-3 in the lower troposphere, we find a significant reduction in error when using the predicted AKs as compared to a single average AK. This study examined data from the continental United States (CONUS) for 2006, but the approach could be applied to other regions and times.
Worden, H. M., M. N. Deeter, C. Frankenberg, M. George, F. Nichitiu, J. Worden, I. Aben, K. W. Bowman, C. Clerbaux, P. F. Coheur, A. T. J. de Laat, R. Detweiler, J. R. Drummond, D. P. Edwards, J. C. Gille, D. Hurtmans, M. Luo, S. Martínez-Alonso, S. Massie, G. Pfister, and J. X. Warner (2013b), Decadal record of satellite carbon monoxide observations, Atmos. Chem. Phys., 13(2), 837–850, doi:10.5194/acp-13-837-2013.
Atmospheric carbon monoxide (CO) distributions are controlled by anthropogenic emissions, biomass burning, transport and oxidation by reaction with the hydroxyl radical (OH). Quantifying trends in CO is therefore important for understanding changes related to all of these contributions. Here we present a comprehensive record of satellite observations from 2000 through 2011 of total column CO using the available measurements from nadir-viewing thermal infrared instruments: MOPITT, AIRS, TES and IASI. We examine trends for CO in the Northern and Southern Hemispheres along with regional trends for Eastern China, Eastern USA, Europe and India. We find that all the satellite observations are consistent with a modest decreasing trend ~ −1 % yr−1 in total column CO over the Northern Hemisphere for this time period and a less significant, but still decreasing trend in the Southern Hemisphere. Although decreasing trends in the United States and Europe have been observed from surface CO measurements, we also find a decrease in CO over E. China that, to our knowledge, has not been reported previously. Some of the interannual variability in the observations can be explained by global fire emissions, but the overall decrease needs further study to understand the implications for changes in anthropogenic emissions.
Worden, J., K. Wecht, C. Frankenberg, M. Alvarado, K. Bowman, E. Kort, S. Kulawik, M. Lee, V. Payne, and H. Worden (2013c), CH4 and CO distributions over tropical fires during October 2006 as observed by the Aura TES satellite instrument and modeled by GEOS-Chem, Atmos. Chem. Phys., 13(7), 3679–3692, doi:10.5194/acp-13-3679-2013.
Tropical fires represent a highly uncertain source of atmospheric methane (CH4) because of the variability of fire emissions and the dependency of the fire CH4 emission factors (g kg−1 dry matter burned) on fuel type and combustion phase. In this paper we use new observations of CH4 and CO in the free troposphere from the Aura Tropospheric Emission Sounder (TES) satellite instrument to place constraints on the role of tropical fire emissions versus microbial production (e.g. in wetlands and livestock) during the (October) 2006 El Niño, a time of significant fire emissions from Indonesia. We first compare the global CH4 distributions from TES using the GEOS-Chem model. We find a mean bias between the observations and model of 26.3 ppb CH4 that is independent of latitude between 50° S and 80° N, consistent with previous validation studies of TES CH4 retrievals using aircraft measurements. The slope of the distribution of CH4 versus CO as observed by TES and modeled by GEOS-Chem is consistent (within the TES observation error) for air parcels over the Indonesian peat fires, South America, and Africa. The CH4 and CO distributions are correlated between R = 0.42 and R = 0.46, with these correlations primarily limited by the TES random error. Over Indonesia, the observed slope of 0.13 (ppb ppb−1) ±0.01, as compared to a modeled slope of 0.153 (ppb ppb−1) ±0.005 and an emission ratio used within the GEOS-Chem model of approximately 0.11 (ppb ppb−1), indicates that most of the observed methane enhancement originated from the fire. Slopes of 0.47 (ppb ppb−1) ±0.04 and 0.44 (ppb ppb−1) ±0.03 over South America and Africa show that the methane in the observed air parcels primarily came from microbial-generated emissions. Sensitivity studies using GEOS-Chem show that part of the observed correlation for the Indonesian observations and most of the observed correlations over South America and Africa are a result of transport and mixing of the fire and nearby microbial-generated emissions into the observed air parcels. Differences between observed and modeled CH4 distributions over South America and southern Africa indicate that the magnitude of the methane emissions for this time period are inconsistent with observations even if the relative distribution of fire versus biotic emissions are consistent. This study shows the potential for estimation of CH4 emissions over tropical regions using joint satellite observations of CH4 and CO.
Worden, J., Z. Jiang, D. B. A. Jones, M. Alvarado, K. Bowman, C. Frankenberg, E. A. Kort, S. S. Kulawik, M. Lee, J. Liu, V. Payne, K. Wecht, and H. Worden (2013d), El Niño, the 2006 Indonesian peat fires, and the distribution of atmospheric methane, Geophysical Research Letters, 40(18), 4938–4943, doi:10.1002/grl.50937.
Dry conditions from a moderate El Niño during the fall of 2006 resulted in enhanced burning in Indonesia with fire emissions of CO approximately 4–6 times larger than the prior year. Here we use new tropospheric methane and CO data from the Aura Tropospheric Emission Spectrometer and new CO profile measurements from the Terra Measurements of Pollution in the Troposphere (MOPITT) satellite instruments with the Goddard Earth Observing System (GEOS)-Chem model to estimate methane emissions of 4.25 ± 0.75 Tg for October–November 2006 from these fires. Errors in convective parameterization in GEOS-Chem, evaluated by comparing MOPITT and GEOS-Chem CO profiles, are the primary uncertainty of the emissions estimate. The El Niño related Indonesian fires increased the tropical distribution of atmospheric methane relative to 2005, indicating that tropical biomass burning can compensate for expected decreases in tropical wetland methane emissions from reduced rainfall during El Niño as found in previous studies.
Yoon, J., A. Pozzer, P. Hoor, D. Y. Chang, S. Beirle, T. Wagner, S. Schloegl, J. Lelieveld, and H. M. Worden (2013), Technical Note: Temporal change in averaging kernels as a source of uncertainty in trend estimates of carbon monoxide retrieved from MOPITT, Atmos. Chem. Phys., 13(22), 11307–11316, doi:10.5194/acp-13-11307-2013.
It is now possible to monitor the global and long-term trends of trace gases that are important to atmospheric chemistry, climate, and air quality with satellite data records that span more than a decade. However, many of the remote sensing techniques used by satellite instruments produce measurements that have variable sensitivity to the vertical profiles of atmospheric gases. In the case of constrained retrievals like optimal estimation, this leads to a varying amount of a priori information in the retrieval and is represented by an averaging kernel. In this study, we investigate to what extent such trends can be biased by temporal changes of averaging kernels used in the retrieval algorithm. In particular, the surface carbon monoxide data retrieved from the Measurements Of Pollution In The Troposphere (MOPITT) instrument from 2001 to 2010 were analysed. As a practical example based on the MOPITT data, we show that if the true atmospheric mixing ratio is continuously 50% higher or lower than the a priori state, the temporal change of the averaging kernel at the surface level gives rise to an artificial trend in retrieved surface carbon monoxide, ranging from −10.71 to +13.21 ppbv yr−1 (−5.68 to +8.84% yr−1) depending on location. Therefore, in the case of surface (or near-surface level) CO derived from MOPITT, the AKs trends multiplied by the difference between true and a priori states must be quantified in order to estimate trend biases.
Zbinden, R. M., V. Thouret, P. Ricaud, F. Carminati, J.-P. Cammas, and P. Nédélec (2013), Climatology of pure tropospheric profiles and column contents of ozone and carbon monoxide using MOZAIC in the mid-northern  latitudes (24° N to 50° N) from 1994 to 2009, Atmos. Chem. Phys., 13(24), 12363–12388, doi:10.5194/acp-13-12363-2013.
The objective of this paper is to deliver the most accurate ozone (O3) and carbon monoxide (CO) climatology for the pure troposphere only, i.e. exclusively from the ground to the dynamical tropopause on an individual profile basis. The results (profiles and columns) are derived solely from the Measurements of OZone and water vapour by in-service Alrbus airCraft programme (MOZAIC) over 15 years (1994–2009). The study, focused on the northern mid-latitudes [24–50° N] and [119° W–140° E], includes more than 40 000 profiles over 11 sites to give a quasi-global zonal picture. Considering all the sites, the pure tropospheric column peak-to-peak seasonal cycle ranges are 23.7–43.2 DU for O3 and 1.7–6.9 × 10 18 molecules cm−2 for CO. The maxima of the seasonal cycles are not in phase, occurring in February–April for CO and May–July for O3. The phase shift is related to the photochemistry and OH removal efficiencies. The purely tropospheric seasonal profiles are characterized by a typical autumn–winter/spring–summer O3 dichotomy (except in Los Angeles, Eastmed – a cluster of Cairo and Tel Aviv – and the regions impacted by the summer monsoon) and a summer–autumn/winter–spring CO dichotomy. We revisit the boundary-layer, mid-tropospheric (MT) and upper-tropospheric (UT) partial columns using a~new monthly varying MT ceiling. Interestingly, the seasonal cycle maximum of the UT partial columns is shifted from summer to spring for O3 and to very early spring for CO. Conversely, the MT maximum is shifted from spring to summer and is associated with a summer (winter) MT thickening (thinning). Lastly, the pure tropospheric seasonal cycles derived from our analysis are consistent with the cycles derived from spaceborne measurements, the correlation coefficients being r=0.6–0.9 for O3 and r>0.9 for CO. The cycles observed from space are nevertheless greater than MOZAIC for O3 (by 9–18 DU) and smaller for CO (up to 1 × 10 18 molecules cm−2). The larger winter O3 difference between the two data sets suggests probable stratospheric contamination in satellite data due to the tropopause position. The study underlines the importance of rigorously discriminating between the stratospheric and tropospheric reservoirs and avoiding use of a~monthly averaged tropopause position without this strict discrimination in order to assess the pure O3 and CO tropospheric trends.
Zhou, D., A. Ding, H. Mao, C. Fu, T. Wang, L. Y. Chan, K. Ding, Y. Zhang, J. Liu, A. Lu, and N. Hao (2013), Impacts of the East Asian monsoon on lower tropospheric ozone over coastal South China, Environ. Res. Lett., 8(4), 044011, doi:10.1088/1748-9326/8/4/044011.
The impact of the East Asian monsoon (EAM) on climatology and interannual variability of tropospheric ozone (O3) over the coastal South China was investigated by analyzing 11 years of ozonesonde data over Hong Kong with the aid of Lagrangian dispersion modeling of carbon monoxide and calculation of an EAM index. It was found that the seasonal cycle of O3 in the lower troposphere is highly related to the EAM over the study region. Ozone enhancements in the free troposphere are associated with the monsoon-induced transport of pollutants of continental anthropogenic and biomass burning origins. Lower tropospheric O3 levels showed high interannual variability, with an annual averaged amplitude up to 61% of averaged concentrations in the boundary layer (0–1 km altitudes) and 49% below 3 km altitude. In spring and autumn, the interannual variability in boundary layer O3 levels was predominately influenced by the EAM intensity, with high O3 mixing ratios associated with northeasterly circulation anomalies.

2012

August, T., D. Klaes, P. Schlüssel, T. Hultberg, M. Crapeau, A. Arriaga, A. O’Carroll, D. Coppens, R. Munro, and X. Calbet (2012), IASI on Metop-A: Operational Level 2 retrievals after five years in orbit, Journal of Quantitative Spectroscopy and Radiative Transfer, 113(11), 1340–1371, doi:10.1016/j.jqsrt.2012.02.028.
Geophysical parameters from the IASI instrument on Metop-A are essential products provided from EUMETSAT’s Central Facility in near real time. They include vertical profiles of temperature and humidity, related cloud information, surface emissivity and temperature, and atmospheric composition parameters (CO, ozone and several other trace gases). As compared to previous operational processor versions, the latest processor version 5 delivers significant improvements in retrieval performance for most major products. These include improvements to cloud properties products, cloud detection (with a positive impact on the knowledge of the sea surface temperature, SST), the temperature profile (especially in the mid and upper troposphere), and ozone and carbon monoxide total columns. This paper provides a comprehensive summary of the processing algorithms, the latest scientific developments, and the related validation studies and activities. It concludes with a discussion of the future outlook.
Boynard, A., G. G. Pfister, and D. P. Edwards (2012), Boundary layer versus free tropospheric CO budget and variability over the United States during summertime, Journal of Geophysical Research: Atmospheres, 117(D4), n/a–n/a, doi:10.1029/2011JD016416.
The regional Weather Research and Forecasting Model with Chemistry (WRF-Chem) version 3.2 is used to analyze the carbon monoxide (CO) budget and spatiotemporal variability over the United States in summer 2008. CO tracers for different emission sources are used to separate the modeled CO fields into the contributions from individual sources (pollution inflow to the model domain, chemical production within the model domain, and local emissions by type). The implementation of tagged CO tracers into WRF-Chem constitutes an innovative aspect of this work. We evaluate WRF-Chem CO concentrations using aircraft, satellite, and surface observations. The model reproduces fairly well the observed CO concentrations for the entire altitude range but tends to underestimate fire emissions and overestimate anthropogenic sources and CO from pollution inflow. Evaluation results also show that the model gives a good representation of background CO mixing ratios with mean biases better than ∼15 ppbv in the free troposphere (FT) and less than 20 ppbv toward the surface. The analysis of the CO budget over the contiguous United States shows that at the surface, CO from inflow is the dominant source, with a mean relative contribution of 63 ± 19%. Anthropogenic and photochemically produced CO contribute to surface CO to a lesser extent (18 ± 14% and 14 ± 8%, respectively). The average contribution from fire emissions to surface CO during the period examined is small (2 ± 5%) but can have a large impact in certain regions and times. Similar trends are found in the planetary boundary layer (PBL). In the FT, the average CO relative contributions are estimated as 84 ± 12% for CO from inflow, 5 ± 4% for anthropogenic CO, 9 ± 7% for photochemically produced CO, and 1 ± 5% for CO from fires. Using WRF-Chem simulations, we also examine the representation of surface and PBL CO concentration variability that would be captured by current near infrared (NIR) and thermal infrared (TIR) satellite observations. We find that CO total columns are impacted by variability in the lowermost troposphere (LMT) at the ∼10% level, indicating limited sensitivity for air quality applications. The same is generally true for the FT CO column obtained from TIR measurements, although this does provide a good measure for capturing the pollution inflow variability and is therefore valuable in providing initial and boundary conditions to constrain regional models. We further analyze the situations under which the LMT concentrations obtained from recently demonstrated multispectral (NIR + TIR) observations capture the surface CO variability.
Deeter, M. N., H. M. Worden, D. P. Edwards, J. C. Gille, and A. E. Andrews (2012), Evaluation of MOPITT retrievals of lower-tropospheric carbon monoxide over the United States, Journal of Geophysical Research: Atmospheres, 117(D13), n/a–n/a, doi:10.1029/2012JD017553.
The new Version 5 MOPITT (Measurements of Pollution in the Troposphere) product for carbon monoxide (CO) is the first satellite product to exploit simultaneous near-infrared and thermal-infrared observations to enhance retrieval sensitivity in the lower troposphere. This feature is important to air quality analyses and studies of CO sources. However, because of the influence of both thermal contrast and geophysical noise, the retrieval characteristics for this new multispectral product are highly variable. New V5 products for surface-level CO concentrations have been evaluated over the contiguous United States using both in situ vertical profiles and NOAA ground-based “Tall Tower” measurements. Validation results based on the in situ profiles indicate that retrieval biases are on the order of a few percent. However, direct comparisons with the Tall Tower measurements demonstrate that smoothing error, which depends on both the retrieval averaging kernels and CO variability in the lower troposphere, exhibits significant geographical and seasonal variability.
Drori, R., U. Dayan, D. P. Edwards, L. K. Emmons, and C. Erlick (2012), Attributing and quantifying carbon monoxide sources affecting the Eastern Mediterranean: a combined satellite, modelling, and synoptic analysis study, Atmos. Chem. Phys., 12(2), 1067–1082, doi:10.5194/acp-12-1067-2012.
Pollutants from global sources are known to affect the Eastern Mediterranean Shore (EMS). However, there has been no previous study explicitly locating the European sources, characterizing their transport pathways, and quantifying their contribution to local concentrations in the EMS. In the current study, spatially tagged carbon monoxide was used as a tracer for pollutant transport from Europe to the EMS over five consecutive years (2003-2007) using the global chemical transport model MOZART-4. The model results were compared against NOAA/GMD ground station data and remotely sensed data from the Terra/MOPITT satellite and found to agree well on monthly basis but do not agree on daily basis. On synoptic scale, there is agreement between MOZART and GMD during July to August. A budget analysis reveals the role of CO from hydrocarbon oxidation on CO concentration during summer. European anthropogenic emissions were found to significantly influence EM surface concentrations, while European biomass burning (BB) emissions were found to have only a small impact on EM surface concentrations. Over the five simulated years, only two European biomass burning episodes contributed more than 10 ppb to surface CO concentrations in the EM. CO enhancement in the EM during the summer was attributed to synoptic conditions prone to favorable transport from Turkey and Eastern Europe towards the EM rather than increased emissions. We attribute the apparently misleading association between CO emitted from European BB and CO enhancements over the EM to typical summer synoptic conditions caused by the lingering of an anticyclone positioned over the Western and Central Mediterranean Basin that lead to forest fires in the area. Combined with a barometric trough over the eastern part of the Mediterranean Basin, this generates a prevailing transport of air masses from Eastern Europe to the EMS. Synoptic scale variations are shown to change the transport pathways from Europe towards the EMS having an overall small affect. CO concentration over the EMS can be describe as having 3 components: the seasonal cycle, the cycle of CO produced from hydrocarbon oxidation and a synoptic variation.
Fortems-Cheiney, A., F. Chevallier, I. Pison, P. Bousquet, M. Saunois, S. Szopa, C. Cressot, T. P. Kurosu, K. Chance, and A. Fried (2012), The formaldehyde budget as seen by a global-scale multi-constraint and multi-species inversion system, Atmos. Chem. Phys., 12(15), 6699–6721, doi:10.5194/acp-12-6699-2012.
For the first time, carbon monoxide (CO) and formaldehyde (HCHO) satellite retrievals are used together with methane (CH4) and methyl choloroform (CH3CCl3 or MCF) surface measurements in an advanced inversion system. The CO and HCHO are respectively from the MOPITT and OMI instruments. The multi-species and multi-satellite dataset inversion is done for the 2005-2010 period. The robustness of our results is evaluated by comparing our posterior-modeled concentrations with several sets of independent measurements of atmospheric mixing ratios. The inversion leads to significant changes from the prior to the posterior, in terms of magnitude and seasonality of the CO and CH4 surface fluxes and of the HCHO production by non-methane volatile organic compounds (NMVOC). The latter is significantly decreased, indicating an overestimation of the biogenic NMVOC emissions, such as isoprene, in the GEIA inventory. CO and CH4 surface emissions are increased by the inversion, from 1037 to 1394 TgCO and from 489 to 529 TgCH(4) on average for the 2005-2010 period. CH4 emissions present significant interannual variability and a joint CO-CH4 fluxes analysis reveals that tropical biomass burning probably played a role in the recent increase of atmospheric methane.
Herron-Thorpe, F. L., G. H. Mount, L. K. Emmons, B. K. Lamb, S. H. Chung, and J. K. Vaughan (2012), Regional air-quality forecasting for the Pacific Northwest using MOPITT/TERRA assimilated carbon monoxide MOZART-4 forecasts as a near real-time boundary condition, Atmos. Chem. Phys., 12(12), 5603–5615, doi:10.5194/acp-12-5603-2012.
Results from a regional air quality forecast model, AIRPACT-3, were compared to AIRS carbon monoxide column densities for the spring of 2010 over the Pacific Northwest. AIRPACT-3 column densities showed high correlation (R > 0.9) but were significantly biased (similar to 25%) with consistent under-predictions for spring months when there is significant transport from Asia. The AIRPACT-3 CO bias relative to AIRS was eliminated by incorporating dynamic boundary conditions derived from NCAR’s MOZART forecasts with assimilated MOPITT carbon monoxide. Changes in ozone-related boundary conditions derived from MOZART forecasts are also discussed and found to affect background levels by +/- 10 ppb but not found to significantly affect peak ozone surface concentrations.
Hooghiemstra, P. B., M. C. Krol, P. Bergamaschi, A. T. J. de Laat, G. R. van der Werf, P. C. Novelli, M. N. Deeter, I. Aben, and T. Röckmann (2012a), Comparing optimized CO emission estimates using MOPITT or NOAA surface network observations, Journal of Geophysical Research: Atmospheres, 117(D6), n/a–n/a, doi:10.1029/2011JD017043.
This paper compares two global inversions to estimate carbon monoxide (CO) emissions for 2004. Either surface flask observations from the National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA/ESRL) Global Monitoring Division (GMD) or CO total columns from the Measurement of Pollution in the Troposphere (MOPITT) instrument are assimilated in a 4D-Var framework. Inferred emission estimates from the two inversions are consistent over the Northern Hemisphere (NH). For example, both inversions increase anthropogenic CO emissions over Europe (from 46 to 94 Tg CO/yr) and Asia (from 222 to 420 Tg CO/yr). In the Southern Hemisphere (SH), three important findings are reported. First, due to their different vertical sensitivity, the stations-only inversion increases SH biomass burning emissions by 108 Tg CO/yr more than the MOPITT-only inversion. Conversely, the MOPITT-only inversion results in SH natural emissions (mainly CO from oxidation of NMVOCs) that are 185 Tg CO/yr higher compared to the stations-only inversion. Second, MOPITT-only derived biomass burning emissions are reduced with respect to the prior which is in contrast to previous (inverse) modeling studies. Finally, MOPITT derived total emissions are significantly higher for South America and Africa compared to the stations-only inversion. This is likely due to a positive bias in the MOPITT V4 product. This bias is also apparent from validation with surface stations and ground-truth FTIR columns. Our results show that a combined inversion is promising in the NH. However, implementation of a satellite bias correction scheme is essential to combine both observational data sets in the SH.
Hooghiemstra, P. B., M. C. Krol, T. T. van Leeuwen, G. R. van der Werf, P. C. Novelli, M. N. Deeter, I. Aben, and T. Röckmann (2012b), Interannual variability of carbon monoxide emission estimates over South America from 2006 to 2010, Journal of Geophysical Research: Atmospheres, 117(D15), n/a–n/a, doi:10.1029/2012JD017758.
We present the first inverse modeling study to estimate CO emissions constrained by both surface and satellite observations. Our 4D-Var system assimilates National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA/ESRL) Global Monitoring Division (GMD) surface and Measurements Of Pollution In The Troposphere (MOPITT) satellite observations jointly by fitting a bias correction scheme. This approach leads to the identification of a positive bias of maximum 5 ppb in MOPITT column-averaged CO mixing ratios in the remote Southern Hemisphere (SH). The 4D-Var system is used to estimate CO emissions over South America in the period 2006–2010 and to analyze the interannual variability (IAV) of these emissions. We infer robust, high spatial resolution CO emission estimates that show slightly smaller IAV due to fires compared to the Global Fire Emissions Database (GFED3) prior emissions. South American dry season (August and September) biomass burning emission estimates amount to 60, 92, 42, 16 and 93 Tg CO/yr for 2006 to 2010, respectively. Moreover, CO emissions probably associated with pre-harvest burning of sugar cane plantations in São Paulo state are underestimated in current inventories by 50–100%. We conclude that climatic conditions (such as the widespread drought in 2010) seem the most likely cause for the IAV in biomass burning CO emissions. However, socio-economic factors (such as the growing global demand for soy, beef and sugar cane ethanol) and associated deforestation fires, are also likely as drivers for the IAV of CO emissions, but are difficult to link directly to CO emissions.
Huijnen, V., J. Flemming, J. W. Kaiser, A. Inness, J. Leitão, A. Heil, H. J. Eskes, M. G. Schultz, A. Benedetti, J. Hadji-Lazaro, G. Dufour, and M. Eremenko (2012), Hindcast experiments of tropospheric composition during the summer 2010  fires over western Russia, Atmos. Chem. Phys., 12(9), 4341–4364, doi:10.5194/acp-12-4341-2012.
The severe wildfires in western Russia during July-August 2010 coincided with a strong heat wave and led to large emissions of aerosols and trace gases such as carbon monoxide (CO), hydrocarbons and nitrogen oxides into the troposphere. This extreme event is used to evaluate the ability of the global MACC (Monitoring Atmospheric Composition and Climate) atmospheric composition forecasting system to provide analyses of large-scale pollution episodes and to test the respective influence of a priori emission information and data assimilation on the results. Daily 4-day hindcasts were conducted using assimilated aerosol optical depth (AOD), CO, nitrogen dioxide (NO2) and ozone (O-3) data from a range of satellite instruments. Daily fire emissions were used from the Global Fire Assimilation System (GFAS) version 1.0, derived from satellite fire radiative power retrievals. The impact of accurate wildfire emissions is dominant on the composition in the boundary layer, whereas the assimilation system influences concentrations throughout the troposphere, reflecting the vertical sensitivity of the satellite instruments. The application of the daily fire emissions reduces the area-average mean bias by 63% (for CO), 60% (O-3) and 75% (NO2) during the first 24 h with respect to independent satellite observations, compared to a reference simulation with a multi-annual mean climatology of biomass burning emissions. When initial tracer concentrations are further constrained by data assimilation, biases are reduced by 87, 67 and 90%. The forecast accuracy, quantified by the mean bias up to 96 h lead time, was best for all compounds when using both the GFAS emissions and assimilation. The model simulations suggest an indirect positive impact of O-3 and CO assimilation on hindcasts of NO2 via changes in the oxidizing capacity. However, the quality of local hindcasts was strongly dependent on the assumptions made for forecasted fire emissions. This was well visible from a relatively poor forecast accuracy quantified by the root mean square error, as well as the temporal correlation with respect to ground-based CO total column data and AOD. This calls for a more advanced method to forecast fire emissions than the currently adopted persistency approach. The combined analysis of fire radiative power observations, multiple trace gas and aerosol satellite observations, as provided by the MACC system, results in a detailed quantitative description of the impact of major fires on atmospheric composition, and demonstrate the capabilities for the real-time analysis and forecasts of large-scale fire events.
K. Miyazaki, H. J. Eskes, K. Sudo, M. Takigawa, M. van Weele, and K. F. Boersma (2012), Simultaneous assimilation of satellite NO2, O3, CO, and HNO3 data for the analysis of tropospheric chemical composition and emissions, Atmos. Chem. Phys., 12(20), 9545–9579, doi:10.5194/acp-12-9545-2012.
We have developed an advanced chemical data assimilation system to combine observations of chemical compounds from multiple satellites. NO2, O3, CO, and HNO3 measurements from the Ozone Monitoring Instrument (OMI), Tropospheric Emission Spectrometer (TES), Measurement of Pollution in the Troposphere (MOPITT), and Microwave Limb Sounder (MLS) satellite instruments are assimilated into the global chemical transport model CHASER for the years 2006–2007. The CHASER data assimilation system (CHASER-DAS), based on the local ensemble transform Kalman filter technique, simultaneously optimizes the chemical species, as well as the emissions of O3 precursors, while taking their chemical feedbacks into account. With the available datasets, an improved description of the chemical feedbacks can be obtained, especially related to the NOx-CO-OH-O3 set of chemical reactions. Comparisons against independent satellite, aircraft, and ozonesonde data show that the data assimilation results in substantial improvements for various chemical compounds. These improvements include a reduced negative tropospheric NO2 column bias (by 40–85%), a reduced negative CO bias in the Northern Hemisphere (by 40–90%), and a reduced positive O3 bias in the middle and upper troposphere (from 30–40% to within 10%). These changes are related to increased tropospheric OH concentrations by 5–15% in the tropics and the Southern Hemisphere in July. Observing System Experiments (OSEs) have been conducted to quantify the relative importance of each data set on constraining the emissions and concentrations. The OSEs confirm that the assimilation of individual data sets results in a strong influence on both assimilated and non-assimilated species through the inter-species error correlation and the chemical coupling described by the model. The simultaneous adjustment of the emissions and concentrations is a powerful approach to correcting the tropospheric ozone budget and profile analyses.
Kumar, R., M. Naja, G. G. Pfister, M. C. Barth, C. Wiedinmyer, and G. P. Brasseur (2012), Simulations over South Asia using the Weather Research and Forecasting  model with Chemistry (WRF-Chem): chemistry evaluation and initial  results, Geosci. Model Dev., 5(3), 619–648, doi:10.5194/gmd-5-619-2012.
This study presents annual simulations of tropospheric ozone and related species made for the first time using the WRF-Chem model over South Asia for the year 2008. The model-simulated ozone, CO, and NOx are evaluated against ground-based, balloon-borne and satellite-borne (TES, OMI and MOPITT) observations. The comparison of model results with surface ozone observations from seven sites and CO and NOx observations from three sites indicate the model’s ability in reproducing seasonal variations of ozone and CO, but show some differences in NOx. The modeled vertical ozone distribution agrees well with the ozone soundings data from two Indian sites. The vertical distributions of TES ozone and MOPITT CO are generally well reproduced, but the model underestimates TES ozone, OMI tropospheric column NO2 and MOPITT total column CO retrievals during all the months, except MOPITT retrievals during August-January and OMI retrievals during winter. Largest differences between modeled and satellite-retrieved quantities are found during spring when intense biomass burning activity occurs in this region. The evaluation results indicate large uncertainties in anthropogenic and biomass burning emission estimates, especially for NOx. The model results indicate clear regional differences in the seasonality of surface ozone over South Asia, with estimated net ozone production during daytime (1130-1530 h) over inland regions of 0-5 ppbv h(-1) during all seasons and of 0-2 ppbv h(-1) over marine regions during outflow periods. The model results indicate that ozone production in this region is mostly NOx-limited. This study shows that WRF-Chem model captures many important features of the observations and gives confidence to using the model for understanding the spatio-temporal variability of ozone over South Asia. However, improvements of South Asian emission inventories and simulations at finer model resolution, especially over the complex Himalayan terrain in northern India, are also essential for accurately simulating ozone in this region.
Martinez-Alonso, S., M. N. Deeter, H. M. Worden, C. Clerbaux, D. Mao, and J. C. Gille (2012), First satellite identification of volcanic carbon monoxide, Geophys. Res. Lett., 39, doi:10.1029/2012GL053275.
Volcanic degassing produces abundant H2O and CO2, as well as SO2, HCl, H2S, S-2, H-2, HF, CO, and SiF4. Volcanic SO2, HCl, and H2S have been detected from satellites in the past; the remaining species are analyzed in situ or using airborne instruments, with all the consequent limitations in safety and sampling, and at elevated costs. We report identification of high CO concentrations consistent with a volcanic origin (the 2010 Eyjafjallajokull and 2011 Grimsvotn eruptions in Iceland) in data from the Measurements of Pollution in the Troposphere instrument (MOPITT) onboard EOS/Terra. The high CO values coincide spatially and temporally with ash plumes emanating from the eruptive centers, with elevated SO2 and aerosol optical thickness, as well as with high CO values in data from the Infrared Atmospheric Sounding Interferometer (IASI), onboard MetOp-A. CO has a positive indirect radiative forcing; climate models currently do not account for volcanic CO emissions. Given global volcanic CO2 emissions between 130 and 440 Tg/year and volcanic CO: CO2 ratios from the literature, we estimate that average global volcanic CO emissions may be on the order of similar to 5.5 Tg/year, equivalent to the CO emissions caused by combined fossil fuel and biofuel combustion in Australia. Citation: Martinez-Alonso, S., M. N. Deeter, H. M. Worden, C. Clerbaux, D. Mao, and J. C. Gille (2012), First satellite identification of volcanic carbon monoxide, Geophys. Res. Lett., 39, L21809, doi:10.1029/2012GL053275.
Moore, D. P., J. J. Remedios, and A. M. Waterfall (2012), Global distributions of acetone in the upper troposphere from MIPAS spectra, Atmos. Chem. Phys., 12(2), 757–768, doi:10.5194/acp-12-757-2012.
This study reports the first global measurements of acetone (C3H6O) in the upper troposphere (UT). Profiles were obtained between 9 km and 15 km from measurements made by the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard Envisat in August 2003. Errors per profile are lower than 40 % between 180 hPa and 350 hPa. We report strong hemispheric differences in the acetone volume mixing ratios (VMRs), with average concentrations highest in the Northern Hemisphere (NH) mid-latitude UT, between 1000 pptv and 1600 pptv with maxima up to 2300 pptv. Our results show a strong enhancement of acetone relative to CO, particularly over Europe (7 pptv ppbv−1), confirming aircraft studies. Ten-day backward trajectories from these high European values show strong contributions from air flows over North America (56 %) and 25 % from Southernmost Asia. Enhanced acetone is also observed over Greenland, Siberia and biomass burning regions of Africa. Zonal distributions show that acetone VMRs decrease rapidly with increasing altitude (decreasing pressure), particularly in the NH. Poleward of 45° S, acetone VMRs remain fairly consistent with average VMRs between 400 pptv and 500 pptv. In 5-day averages at 9 km, NH VMRs poleward of 45° N are consistently higher than Southern Hemisphere observations poleward of 45° S, by between 750 pptv and 1100 pptv. The results show a clear influence of mid-latitude and transport processes on the acetone summertime distribution.
Morgenstern, O., G. Zeng, S. W. Wood, J. Robinson, D. Smale, C. Paton-Walsh, N. B. Jones, and D. W. T. Griffith (2012), Long-range correlations in Fourier transform infrared, satellite, and  modeled CO in the Southern Hemisphere, J. Geophys. Res.-Atmos., 117, doi:10.1029/2012JD017639.
We use Fourier transform infrared ground-based measurements and satellite and model data to assess long-range correlations in tropospheric carbon monoxide. We find that CO columns measured in New Zealand correlate well with those measured in Antarctica, if a transport-related lag is taken into account. The model suggests that this long-range correlation is part of a mode of anomalous CO comprising almost the whole southern extratropics, which is linked to biomass burning in the southern continents. No such mode is modeled for the Northern Hemisphere. The area of long-range correlations maximizes for the southern subtropical Pacific, which is identified as an advantageous location for a hypothetical new measurement station. The satellite data (produced by the Measurements of Pollution in the Troposphere (MOPITT) instrument) partially confirm these findings but with generally reduced correlations. In particular, the satellite data suggest no long-range correlation at high latitudes. This is partially explained in terms of retrieval limitations and partially reflects a model deficiency.
Parrington, M., P. I. Palmer, D. K. Henze, D. W. Tarasick, E. J. Hyer, R. C. Owen, D. Helmig, C. Clerbaux, K. W. Bowman, M. N. Deeter, E. M. Barratt, P.-F. Coheur, D. Hurtmans, Z. Jiang, M. George, and J. R. Worden (2012), The influence of boreal biomass burning emissions on the distribution of tropospheric ozone over North America and the North Atlantic during 2010, Atmos. Chem. Phys., 12(4), 2077–2098, doi:10.5194/acp-12-2077-2012.
We have analysed the sensitivity of the tropospheric ozone distribution over North America and the North Atlantic to boreal biomass burning emissions during the summer of 2010 using the GEOS-Chem 3-D global tropospheric chemical transport model and observations from in situ and satellite instruments. We show that the model ozone distribution is consistent with observations from the Pico Mountain Observatory in the Azores, ozonesondes across Canada, and the Tropospheric Emission Spectrometer (TES) and Infrared Atmospheric Sounding Instrument (IASI) satellite instruments. Mean biases between the model and observed ozone mixing ratio in the free troposphere were less than 10 ppbv. We used the adjoint of GEOS-Chemto show the model ozone distribution in the free troposphere over Maritime Canada is largely sensitive to NOx emissions from biomass burning sources in Central Canada, lightning sources in the central US, and anthropogenic sources in the eastern US and southeastern Canada. We also used the adjoint of GEOS-Chem to evaluate the Fire Locating And Monitoring of Burning Emissions (FLAMBE) inventory through assimilation of CO observations from the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument. The CO inversion showed that, on average, the FLAMBE emissions needed to be reduced to 89% of their original values, with scaling factors ranging from 12% to 102 %, to fit the MOPITT observations in the boreal regions. Applying the CO scaling factors to all species emitted from boreal biomass burning sources led to a decrease of the model tropospheric distributions of CO, PAN, and NOx by as much as -20 ppbv, -50 pptv, and -20 pptv respectively. The modification of the biomass burning emission estimates reduced the model ozone distribution by approximately -3 ppbv (-8%) and on average improved the agreement of the model ozone distribution compared to the observations throughout the free troposphere, reducing the mean model bias from 5.5 to 4.0 ppbv for the Pico Mountain Observatory, 3.0 to 0.9 ppbv for ozonesondes, 2.0 to 0.9 ppbv for TES, and 2.8 to 1.4 ppbv for IASI.
Pozzer, A., P. Zimmermann, U. M. Doering, J. van Aardenne, H. Tost, F. Dentener, G. Janssens-Maenhout, and J. Lelieveld (2012), Effects of business-as-usual anthropogenic emissions on air quality, Atmos. Chem. Phys., 12(15), 6915–6937, doi:10.5194/acp-12-6915-2012.
The atmospheric chemistry general circulation model EMAC has been used to estimate the impact of anthropogenic emission changes on global and regional air quality in recent and future years (2005, 2010, 2025 and 2050). The emission scenario assumes that population and economic growth largely determine energy and food consumption and consequent pollution sources with the current technologies (“business as usual”). This scenario is chosen to show the effects of not implementing legislation to prevent additional climate change and growing air pollution, other than what is in place for the base year 2005, representing a pessimistic (but plausible) future.  By comparing with recent observations, it is shown that the model reproduces the main features of regional air pollution distributions though with some imprecisions inherent to the coarse horizontal resolution (similar to 100 km) and simplified bottom-up emission input.  To identify possible future hot spots of poor air quality, a multi pollutant index (MPI), suited for global model output, has been applied. It appears that East and South Asia and the Middle East represent such hotspots due to very high pollutant concentrations, while a general increase of MPIs is observed in all populated regions in the Northern Hemisphere. In East Asia a range of pollutant gases and fine particulate matter (PM2.5) is projected to reach very high levels from 2005 onward, while in South Asia air pollution, including ozone, will grow rapidly towards the middle of the century. Around the Persian Gulf, where natural PM2.5 concentrations are already high (desert dust), ozone levels are expected to increase strongly.  The population weighted MPI (PW-MPI), which combines demographic and pollutant concentration projections, shows that a rapidly increasing number of people worldwide will experience reduced air quality during the first half of the 21st century. Following this business as usual scenario, it is projected that air quality for the global average citizen in 2050 would be almost comparable to that for the average citizen in East Asia in the year 2005, which underscores the need to pursue emission reductions.
Safronov, A. N., E. V. Fokeeva, V. S. Rakitin, L. N. Yurganov, and E. I. Grechko (2012), Carbon monoxide emissions in summer 2010 in the central part of the Russian Plain and estimation of their uncertainties with the use of different land-cover maps, Izv. Atmos. Ocean. Phys., 48(9), 925–940, doi:10.1134/S0001433812090150.
This study is devoted to estimation of carbon monoxide (CO) emissions during the wildfires of the anomalously hot 2010 summer in the central part of the Russian Plain. CO emissions from the forest wildfires have been estimated with use of the Active Fires (AF) (MODIS MCD14ML) and Burned Areas (BA) (MODIS MCD45) methods for AVHRR/UDM, Global Land Cover 2000 (GLC 2000), GlobCover, and MCD12Q1 vegetation maps. A comparison of the vegetation maps and investigation of forest structure dynamics for the period from 2005 to 2009 have been carried out. It is shown that the major uncertainties during the estimation of CO in decreasing order are the following: distinctions in emission-calculation methods, differences in the vegetation maps used, differences in satellite data from Terra and Aqua, and the insufficient registration of forest structure dynamics. For additional comparison of estimations obtained by an independent method with the use of orbital (MOPITT, AIRS, and IASI) and ground-based (Moscow and Zvenigorod) spectroscopic measurements of CO content were presented.
Srivastava, S., S. Lal, S. Venkataramani, S. Gupta, and V. Sheel (2012), Surface distributions of O3, CO and hydrocarbons over the Bay of Bengal and the Arabian Sea during pre-monsoon season, Atmospheric Environment, 47, 459–467, doi:10.1016/j.atmosenv.2011.10.023.
Mixing ratios of ozone (O3), carbon monoxide (CO), methane (CH4) and few light non methane hydrocarbons (NMHCs) were measured on board the ocean research vessel Sagar Kanya over the Bay of Bengal and the Arabian Sea during the spring of 2006 as a part of an Integrated Campaign for Aerosol, gases and Radiation Budget (ICARB). North-westerly winds prevailing during this period transport large amount of anthropogenic pollutants from the Indo-Gangetic Plain (IGP) to the northern part of Bay of Bengal. The south-westerly and north-westerly winds carried cleaner marine air having lower abundance of pollutants over the southern Bay of Bengal and Arabian Sea. Ozone, CH4, CO, ethane and n-butane are found to be well correlated with each other over the northern Bay of Bengal indicating their common co-located sources. The latitudinal gradients of these species are found to be significant (O3 ∼ 5.4 ppbv deg−1, CH4 ∼ 5.3 ppbv deg−1, CO ∼ 10 ppbv deg−1, ethane ∼ 93.2 pptv deg−1 and n-butane ∼ 59.7 pptv deg−1) over this region. Surprisingly, and in contrast to over the Bay of Bengal, the mixing ratios of these trace gases over the Arabian Sea are found comparatively higher over the southern region than over the northern region leading to negative latitudinal gradients. The short lived species with oceanic sources like ethene and propene show large variability and higher mixing ratios over southern parts of both the marine regions. These observations are compared with previous measurements made over these marine regions and the results obtained from the 3D MOZART chemistry transport model. The present study shows that the two marine regions adjacent to the Indian subcontinent are completely different from the perspective of surface level distributions of these species.
Su, M., Y. Lin, X. Fan, L. Peng, and C. Zhao (2012), Impacts of global emissions of CO, NO x , and CH4 on China tropospheric hydroxyl free radicals, Adv. Atmos. Sci., 29(4), 838–854, doi:10.1007/s00376-012-1229-2.
Using the global chemistry and transport model MOZART, the simulated distributions of tropospheric hydroxyl free radicals (OH) over China and its sensitivities to global emissions of carbon monoxide (CO), nitrogen oxide (NO x ), and methane (CH4) were investigated in this study. Due to various distributions of OH sources and sinks, the concentrations of tropospheric OH in east China are much greater than in west China. The contribution of NO + perhydroxyl radical (HO2) reaction to OH production in east China is more pronounced than that in west China, and because of the higher reaction activity of non-methane volatile organic compounds (NMVOCs), the contributions to OH loss by NMVOCs exceed those of CO and take the dominant position in summer. The results of the sensitivity runs show a significant increase of tropospheric OH in east China from 1990 to 2000, and the trend continues. The positive effect of double emissions of NO x on OH is partly offset by the contrary effect of increased CO and CH4 emissions: the double emissions of NO x will cause an increase of OH of 18.1%–30.1%, while the increases of CO and CH4 will cause a decrease of OH of 12.2%–20.8% and 0.3%–3.0%, respectively. In turn, the lifetimes of CH4, CO, and NO x will increase by 0.3%–3.1% with regard to double emissions of CH4, 13.9%–26.3% to double emissions of CO and decrease by 15.3%–23.2% to double emissions of NO x .
Vidot, J., J. Landgraf, O. P. Hasekamp, A. Butz, A. Galli, P. Tol, and I. Aben (2012), Carbon monoxide from shortwave infrared reflectance measurements: A new  retrieval approach for clear sky and partially cloudy atmospheres, Remote Sens. Environ., 120, 255–266, doi:10.1016/j.rse.2011.09.032.
The GMES atmospheric services include global and European air quality monitoring and forecasting which require near real time delivery of atmospheric CO abundances. To achieve this, a numerically efficient retrieval approach for operational data processing is needed to derive CO column densities from shortwave infrared measurements in the 2.3 mu m band of the Sentinel 5 missions and its Precursor mission. The expected performance of both spectrometers will allow for clear-sky CO column retrievals over land with a precision of <= 10% and an overall accuracy of <= 15% even for background CO abundance and low surface reflection in the shortwave infrared spectral range. In this context, we present a new algorithm approach of the retrieval of CO from shortwave infrared measurements in clear sky and partially cloudy atmospheres over land and ocean surfaces. The algorithm employs simplified radiative transfer, where the model atmosphere is separated in a clear sky part, and a part which is bounded below by an elevated Lambertian reflector to account for atmospheric scattering by clouds and aerosols. Within the inversion scheme, Tikhonov regularization is used to determine, for each individual measurement, not only the vertically integrated CO column density and its retrieval error, but also the column averaging kernel. For the retrieval, a prior estimate of methane abundance is used to characterize the light path by retrieving effective cloud parameters from the shortwave infrared band itself. A performance analysis shows that, for a single cloud layer in the middle and lower troposphere, the bias on the CO retrieval due to the Lambertian cloud model is less than 2-3%. The effect of boundary layer aerosols can also be treated with similar accuracy. In contrast, the presence of elevated dust plumes above bright surfaces or a single layer cirrus cloud causes significant errors and, in these cases, a reasonably low retrieval bias can only be achieved for an optical depth in the shortwave infrared spectral range lower than 0.4. Another relevant error source for the CO retrieval algorithm is given by the prior uncertainty of methane. It is found that a 5% uncertainty in the methane column density causes biases of 3-9% on the retrieved CO column, depending on cloud fraction. (C) 2012 Elsevier Inc. All rights reserved.
Worden, H. M., Y. Cheng, G. Pfister, G. R. Carmichael, Q. Zhang, D. G. Streets, M. Deeter, D. P. Edwards, J. C. Gille, and J. R. Worden (2012), Satellite-based estimates of reduced CO and CO2 emissions due to traffic  restrictions during the 2008 Beijing Olympics, Geophys. Res. Lett., 39, L14802, doi:10.1029/2012GL052395.
During the 2008 Olympics, the Chinese government made a significant effort to improve air quality in Beijing, including restrictions on traffic. Here we estimate the reductions in carbon monoxide (CO) and carbon dioxide (CO2) emissions resulting from the control measures on Beijing transportation. Using MOPITT (Measurements Of Pollution In The Troposphere) multispectral satellite observations of near-surface CO along with WRF-Chem (Weather Research and Forecasting model with Chemistry) simulations for Beijing during August, 2007 and 2008, we estimate changes in CO due to meteorology and transportation sector emissions. Applying a reported CO/CO2 emission ratio for fossil fuels, we find the corresponding reduction in CO2, 60 +/- 36 Gg[CO2]/day. As compared to emission scenarios being considered for the IPCC AR5 (Intergovernmental Panel on Climate Change, 5th Assessment Report), this result suggests that urban traffic controls on the Beijing Olympics scale could play a significant role in meeting target reductions for global CO2 emissions. Citation: Worden, H.M., Y. Cheng, G. Pfister, G.R. Carmichael, Q. Zhang, D.G. Streets, M. Deeter, D.P. Edwards, J.C. Gille, and J.R. Worden (2012), Satellite-based estimates of reduced CO and CO2 emissions due to traffic restrictions during the 2008 Beijing Olympics, Geophys. Res. Lett., 39, L14802, doi:10.1029/2012GL052395.
Yumimoto, K., and I. Uno (2012), Inverse Estimate of Long-Term CO Emission in China between 2005-2010 with Green’s Function Method, Journal of Japan Society for Atmospheric Environment/Taiki Kankyo Gakkaishi, 47(4), 162–172.
Carbon monoxide (CO) emission amounts in China are inversely optimized with Green’s functions method, CO vertical profile measurements from MOPITT satellite instrument, and the GEOS-Chem chemical transport model (CTM) for the recent 6 years (2005 - 2010). Observations from surface sites (JMA and NOAA/GMD) are used for independent validation of a posteriori emissions. Model simulations with a posteriori emissions successfully reproduce the CO outflows from China to East China Sea and the Japanese archipelago in winter and spring, and compensate the under-estimates over the central eastern China region, considerably. A posteriori emissions in China exhibit significant seasonal variation in which the seasonal peak and bottom are found in winter-spring and summer, respectively. The CO emission in March is on average 54 % higher than in August. This seasonal cycle is consistent with other recent studies. Chinese CO sources obtained by the inversion are 164.5, 171.5, 180.8, 160.3, 152.5, and 156.1 Tg/year for 2005-2010, respectively, presenting inter-annual variations due to socioeconomic conditions (e.g., controls on pollutant emissions by the 2008 Beijing Olympic game and the global depression in 2009).
Zhang, Y., Y. Chen, G. Sarwar, and K. Schere (2012), Impact of gas-phase mechanisms on Weather Research Forecasting Model with Chemistry (WRF/Chem) predictions: Mechanism implementation and comparative evaluation, Journal of Geophysical Research: Atmospheres, 117(D1), doi:10.1029/2011JD015775. [online] Available from: http://onlinelibrary.wiley.com/doi/10.1029/2011JD015775/abstract .
Gas-phase mechanisms provide important oxidant and gaseous precursors for secondary aerosol formation. Different gas-phase mechanisms may lead to different predictions of gases, aerosols, and aerosol direct and indirect effects. In this study, WRF/Chem-MADRID simulations are conducted over the continental United States for July 2001, with three different gas-phase mechanisms, a default one (i.e., CBM-Z) and two newly implemented ones (i.e., CB05 and SAPRC-99). Simulation results are evaluated against available surface observations, satellite data, and reanalysis data. The model with these three gas-phase mechanisms gives similar predictions of most meteorological variables in terms of spatial distribution and statistics, but large differences exist in shortwave radiation and temperature and relative humidity at 2 m at individual sites under cloudy conditions, indicating the importance of aerosol semi-direct and indirect effects on these variables. Large biases exist in the simulated wind speed at 10 m, cloud water path, cloud optical thickness, and precipitation, due to uncertainties in current cloud microphysics and surface layer parameterizations. Simulations with all three gas-phase mechanisms well reproduce surface concentrations of O3, CO, NO2, and PM2.5, and column NO2. Larger biases exist in the surface concentrations of nitrate and organic matter (OM) and in the spatial distribution of column CO, tropospheric ozone residual, and aerosol optical depth, due to uncertainties in primary OM emissions, limitations in model representations of chemical transport, and radiative processes. Different gas-phase mechanisms lead to different predictions of mass concentrations of O3 (up to 5 ppb), PM2.5 (up to 0.5 μg m−3), secondary inorganic PM2.5 species (up to 1.1 μg m−3), organic PM (up to 1.8 μg m−3), and number concentration of PM2.5 (up to 2 × 104 cm−3). Differences in aerosol mass and number concentrations further lead to sizeable differences in simulated cloud condensation nuclei (CCN) and cloud droplet number concentration (CDNC) due to the feedback mechanisms among H2SO4 vapor, PM2.5 number, CCN, and CDNC through gas-phase chemistry, new particle formation via homogeneous nucleation, aerosol growth, and aerosol activation by cloud droplets. This study illustrates the important impact of gas-phase mechanisms on chemical and aerosol predictions, their subsequent effects on meteorological predictions, and a need for an accurate representation of such feedbacks through various atmospheric processes in the model. The online-coupled models that simulate feedbacks between meteorological variables and chemical species may provide more accurate representations of the real atmosphere for regulatory applications and can be applied to simulate chemistry-climate feedbacks over a longer period of time.
Zhao, Y., C. P. Nielsen, M. B. McElroy, L. Zhang, and J. Zhang (2012), CO emissions in China: Uncertainties and implications of improved energy efficiency and emission control, Atmospheric Environment, 49, 103–113, doi:10.1016/j.atmosenv.2011.12.015.
A bottom-up methodology and an improved database of emission factors combining the latest domestic field measurements are developed to estimate the emissions of anthropogenic CO from China at national and provincial levels. The CO emission factors for major economic sectors declined to varying degrees from 2005 to 2009, attributed to improved energy efficiency and/or emission control regulations. Total national CO emissions are estimated at 173 Tg for 2005 and have been relatively stable for subsequent years, despite fast growth of energy consumption and industrial production. While industry and transportation sources dominated CO emissions in developed eastern and north-central China, residential combustion played a much greater role in the less developed western provinces. The uncertainties of national Chinese CO emissions are quantified using Monte Carlo simulation at -20% to +45% (95% confidence interval). Due to poor understanding of emission factors and activity levels for combustion of solid fuels, the largest uncertainties are found for emissions from the residential sector. The trends of bottom-up emissions compare reasonably to satellite observation of CO columns and to ground observations of CO2-CO correlation slopes. The increase in the ratio for emissions of CO2 relative to CO suggests that China has successfully improved combustion efficiencies across its economy in recent years, consistent with national policies to improve energy efficiency and to control criteria air pollutants.

2011

Bouarar, I., K. S. Law, M. Pham, C. Liousse, H. Schlager, T. Hamburger, C. E. Reeves, J.-P. Cammas, P. Nédéléc, S. Szopa, F. Ravegnani, S. Viciani, F. D’Amato, A. Ulanovsky, and A. Richter (2011), Emission sources contributing to tropospheric ozone over Equatorial Africa during the summer monsoon, Atmos. Chem. Phys., 11(24), 13395–13419, doi:10.5194/acp-11-13395-2011.
A global chemistry-climate model LMDz_INCA is used to investigate the contribution of African and Asian emissions to tropospheric ozone over Central and West Africa during the summer monsoon. The model results show that ozone in this region is most sensitive to lightning NOx and to Central African biomass burning emissions. However, other emission categories also contribute significantly to regional ozone. The maximum ozone changes due to lightning NOx occur in the upper troposphere between 400 hPa and 200 hPa over West Africa and downwind over the Atlantic Ocean. Biomass burning emissions mainly influence ozone in the lower and middle troposphere over Central Africa, and downwind due to westward transport. Biogenic emissions of volatile organic compounds, which can be uplifted from the lower troposphere to higher altitudes by the deep convection that occurs over West Africa during the monsoon season, lead to maximum ozone changes in the lower stratosphere region. Soil NOx emissions over the Sahel region make a significant contribution to ozone in the lower troposphere. In addition, convective uplift of these emissions and subsequent ozone production are also an important source of ozone in the upper troposphere over West Africa. Concerning African anthropogenic emissions, they only make a small contribution to ozone compared to the other emission categories. The model results indicate that most ozone changes due to African emissions occur downwind, especially over the Atlantic Ocean, far from the emission regions. The import of Asian emissions also makes a considerable contribution to ozone concentrations above 150 hPa and has to be taken into account in studies of the ozone budget over Africa. Using IPCC AR5 (Intergovernmental Panel on Climate Change; Fifth Assessment Report) estimates of anthropogenic emissions for 2030 over Africa and Asia, model calculations show larger changes in ozone over Africa due to growth in Asian emissions compared to African emissions over the next 20 yr.
Deeter, M. N., H. M. Worden, J. C. Gille, D. P. Edwards, D. Mao, and J. R. Drummond (2011), MOPITT multispectral CO retrievals: Origins and effects of geophysical radiance errors, Journal of Geophysical Research: Atmospheres, 116(D15), n/a–n/a, doi:10.1029/2011JD015703.
An obstacle to the simultaneous use of near-infrared (NIR) and thermal infrared (TIR) observations from the Measurements of Pollution in the Troposphere (MOPITT) instrument has been a lack of understanding of NIR radiance errors. Retrieval uncertainties produced by optimal estimation-based retrieval algorithms used for satellite instruments like MOPITT are only meaningful if radiance error statistics are accurately quantified in the measurement error covariance matrix. MOPITT’s gas correlation radiometers are subject to a unique form of “geophysical noise” due to the combined effects of (1) translational motion of the instrumental field of view during a single observation and (2) fine-scale spatial variability of surface radiative properties. We describe and demonstrate a new method for quantifying this source of error for each observation. Both TIR and NIR radiance errors due to this effect are highly variable, especially over land, but are qualitatively consistent with the variability of Moderate Resolution Imaging Spectroradiometer radiances in similar spectral bands. In addition, retrieval algorithm modifications are described which adjust the trade-off between smoothing error and retrieval noise within the optimal estimation framework. These modifications are necessary to fully exploit the information in MOPITT’s NIR channels. A case study based on MOPITT observations over Minnesota demonstrates significant improvement in retrieval performance as the result of the retrieval algorithm modifications.
Fokeeva, E. V., A. N. Safronov, V. S. Rakitin, L. N. Yurganov, E. I. Grechko, and R. A. Shumskii (2011), Investigation of the 2010 July-August fires impact on carbon monoxide  atmospheric pollution in Moscow and its outskirts, estimating of  emissions, Izv. Atmos. Ocean. Phys., 47(6), 682–698, doi:10.1134/S0001433811060041.
We investigate the air pollution in the central European part of Russia during the 2010 summer fires. The results of ground-based (Institute of Atmospheric Physics (IAP), Moscow State University (MSU), and Zvenigorod Scientific Station (ZSS)) and satellite (MOPITT, AIRS, of Terra and Aqua satellites) measurements of the total content and concentration of carbon monoxide (CO), as well as MODIS data on the spatial and temporal distribution of forest and peat fires obtained from Terra and Aqua satellites, are presented. A comparison between similar situations in 2010 and 2002 revealed the causes of higher pollution levels in 2010. The use of trajectory analysis, detailed space imagery, and model calculations made it possible to reveal the location of peat fires and their contribution to the air pollution over the Moscow megalopolis. Fireemission estimates were obtained using two independent methods.
Fortems-Cheiney, A., F. Chevallier, I. Pison, P. Bousquet, S. Szopa, M. N. Deeter, and C. Clerbaux (2011), Ten years of CO emissions as seen from Measurements of Pollution in the Troposphere (MOPITT), Journal of Geophysical Research (Atmospheres), 116(d15), 5304, doi:10.1029/2010JD014416.
The Measurements of Pollution in the Troposphere (MOPITT) retrievals are used as top-down constraints in an inversion for global CO emissions, for the past 10 years (from March 2000 to December 2009), at 8 day and 3.75° × 2.75° (longitude, latitude) resolution. The method updates a standard prior inventory and yields large increments in terms of annual regional budgets and seasonality. Our validation strategy consists in comparing our posterior-modeled concentrations with several sets of independent measurements: surface measurements, aircraft, and satellite. The posterior emissions, with a global 10 year average of 1430 TgCO/yr, are 37% higher than the prior ones, built from the EDGAR 3.2 and the GFEDv2 inventories (1038 TgCO/yr on average). In addition, they present some significant seasonal variations in the Northern Hemisphere that are not present in our prior nor in others’ major inventories. Our results also exhibit some large interannual variability due to biomass burning emissions, climate, and socioeconomic factors; CO emissions range from 1504 TgCO (in 2007) to 1318 TgCO (in 2009).
Ghude, S. D., S. H. Kulkarni, P. S. Kulkarni, V. P. Kanawade, S. Fadnavis, S. Pokhrel, C. Jena, G. Beig, and D. Bortoli (2011a), Anomalous low tropospheric column ozone over Eastern India during the severe drought event of monsoon 2002: a case study, Environ Sci Pollut Res, 18(8), 1442–1455, doi:10.1007/s11356-011-0506-4.
Background, aim, and scope The present study is an attempt to examine some of the probable causes of the unusually low tropospheric column ozone observed over eastern India during the exceptional drought event in July 2002. Method We examined horizontal wind and omega (vertical velocity) anomalies over the Indian region to understand the large-scale dynamical processes which prevailed in July 2002. We also examined anomalies in tropospheric carbon monoxide (CO), an important ozone precursor, and observed low CO mixing ratio in the free troposphere in 2002 over eastern India. Results and discussion It was found that instead of a normal large-scale ascent, the air was descending in the middle and lower troposphere over a vast part of India. This configuration was apparently responsible for the less convective upwelling of precursors and likely caused less photochemical ozone formation in the free troposphere over eastern India in July 2002. Conclusion The insight gained from this case study will hopefully provide a better understanding of the process controlling the distribution of the tropospheric ozone over the Indian region.
Ghude, S. D., G. Beig, P. S. Kulkarni, V. P. Kanawade, S. Fadnavis, J. J. Remedios, and S. H. Kulkarni (2011b), Regional CO pollution over the Indian-subcontinent and various transport  pathways as observed by MOPITT, Int. J. Remote Sens., 32(21), 6133–6148, doi:10.1080/01431161.2010.507796.
We used day-side Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO) retrievals (2000-2007) to examine the regional CO emission and its transport pathways during the summer/winter monsoon, with a specific focus on the Indian-subcontinent. It is observed that MOPITT CO retrievals at 850 hPa level in general show large scale features of CO emission in India, as reflected in the bottom-up inventory. In particular, high CO mixing ratios over the eastern north-eastern part of India, along the Indo-Gangetic (IG) region, and low CO mixing ratios over central India are generally captured from the MOPITT data. A strong plume with enhanced CO mixing ratios at 350 hPa is observed during the summer monsoon, demonstrating large scale vertical transport of the boundary layer CO from the Indian region into the upper troposphere. During winter outflow CO from the Indian region is found to be transported over the Arabian Sea and Bay of Bengal and reaches up to Saudi Arabia and north-eastern Africa. It is observed that emissions from Southeast Asia and the eastern north-eastern Indian region have the greatest impact over the Bay of Bengal and the eastern Indian Ocean, while emissions from the rest of India dominate over the Arabian Sea and the western Indian Ocean.
Gonzi, S., L. Feng, and P. I. Palmer (2011), Seasonal cycle of emissions of CO inferred from MOPITT profiles of CO: Sensitivity to pyroconvection and profile retrieval assumptions, Geophysical Research Letters, 38(8), n/a–n/a, doi:10.1029/2011GL046789.
We estimate monthly continental-scale CO emissions for 2006 by optimally fitting prior emissions used by the GEOS-Chem chemistry transport model to retrieved profile measurements of CO from the Measurement Of Pollution In The Troposphere (MOPITT) satellite instrument. We focus on the range of emission estimates obtained by using different versions of the MOPITT profile data, and by better describing enhanced vertical mixing of emissions from wildfires. We find that annual posterior CO emissions estimates for 2006 range from 1003 to 1180 Tg CO, within the range of prior estimates (1243 ± 617 Tg CO). We generally find larger differences in posterior CO emissions from using different versions of the MOPITT data than from improving the description of wildfires, with the exception of fires over Indonesia. Posterior emissions over regions with wildfires have a large seasonal cycle, as expected, which can be substantially different from prior emission estimates. We find GFEDv2 prior emissions underestimate the duration of the biomass burning season for North Africa by as much as 1 month. We also find posterior emissions over Indonesia are a factor of 2 higher than prior emissions (83 ± 42 Tg CO) in 2006 due to widespread fires during July–December. Posterior emissions over Canada during 2006 are a factor of 2–3 higher than prior emissions (9 ± 4.6 Tg CO). We also find a seasonal cycle of CO emissions over North America and Europe, in agreement with previous studies, which is not described by prior emissions.
Hao, N., P. Valks, D. Loyola, Y. F. Cheng, and W. Zimmer (2011), Space-based measurements of air quality during the World Expo 2010 in Shanghai, Environ. Res. Lett., 6(4), 044004, doi:10.1088/1748-9326/6/4/044004.
During the World Exposition 2010 (Expo, from May to October), emission control measures were implemented in Shanghai and surrounding areas to improve the air quality. To evaluate the effect of these measures, we use the tropospheric NO2 column, aerosol optical thickness (AOT) and CO concentration observations from the satellite instruments GOME-2, MODIS and MOPITT, respectively. The analysis shows about 8% and 14% reductions of tropospheric NO2 columns and AOT respectively over Shanghai during the Expo period, compared to the past three years. A 12% reduction of CO concentration at 700 hPa over Shanghai and surrounding areas is found during the Expo period. On the other hand, the satellite measurements show increases of NO2 by 20% and AOT by 23% over Shanghai urban areas after the Expo (November 2010–April 2011), when the short-term emission control measures were lifted. Our study indicates that the air quality measures were effective in Shanghai and surrounding provinces during the Expo period.
Hooghiemstra, P. B., M. C. Krol, J. F. Meirink, P. Bergamaschi, G. R. van der Werf, P. C. Novelli, I. Aben, and T. Röckmann (2011), Optimizing global CO emission estimates using a four-dimensional variational data assimilation system and surface network observations, Atmos. Chem. Phys., 11(10), 4705–4723, doi:10.5194/acp-11-4705-2011.
We apply a four-dimensional variational (4D-VAR) data assimilation system to optimize carbon monoxide (CO) emissions for 2003 and 2004 and to reduce the uncertainty of emission estimates from individual sources using the chemistry transport model TM5. The system is designed to assimilate large (satellite) datasets, but in the current study only a limited amount of surface network observations from the National Oceanic and Atmospheric Administration Earth System Research Laboratory (NOAA/ESRL) Global Monitoring Division (GMD) is used to test the 4D-VAR system. By design, the system is capable to adjust the emissions in such a way that the posterior simulation reproduces background CO mixing ratios and large-scale pollution events at background stations. Uncertainty reduction up to 60% in yearly emissions is observed over well-constrained regions and the inferred emissions compare well with recent studies for 2004. However, with the limited amount of data from the surface network, the system becomes data sparse resulting in a large solution space. Sensitivity studies have shown that model uncertainties (e. g., vertical distribution of biomass burning emissions and the OH field) and the prior inventories used, influence the inferred emission estimates. Also, since the observations only constrain total CO emissions, the 4D-VAR system has difficulties in separating anthropogenic and biogenic sources in particular. The inferred emissions are validated with NOAA aircraft data over North America and the agreement is significantly improved from the prior to posterior simulation. Validation with the Measurements Of Pollution In The Troposphere (MOPITT) instrument version 4 (V4) shows a slight improved agreement over the well-constrained Northern Hemisphere and in the tropics (except for the African continent). However, the model simulation with posterior emissions underestimates MOPITT CO total columns on the remote Southern Hemisphere (SH) by about 10 %. This is caused by a reduction in SH CO sources mainly due to surface stations on the high southern latitudes.
Illingworth, S. M., J. J. Remedios, H. Boesch, S.-P. Ho, D. P. Edwards, P. I. Palmer, and S. Gonzi (2011), A comparison of OEM CO retrievals from the IASI and MOPITT instruments, Atmospheric Measurement Techniques, 4, 775–793, doi:10.5194/amt-4-775-2011.
Observations of atmospheric carbon monoxide (CO) can only be made on continental and global scales by remote sensing instruments situated in space. One such instrument is the Infrared Atmospheric Sounding Interferometer (IASI), producing spectrally resolved, top-of-atmosphere radiance measurements from which CO vertical layers and total columns can be retrieved. This paper presents a technique for intercomparisons of satellite data with low vertical resolution. The example in the paper also generates the first intercomparison between an IASI CO data set, in this case that produced by the University of Leicester IASI Retrieval Scheme (ULIRS), and the V3 and V4 operationally retrieved CO products from the Measurements Of Pollution In The Troposphere (MOPITT) instrument. The comparison is performed for a localised region of Africa, primarily for an ocean day-time configuration, in order to develop the technique for instrument intercomparison in a region with well defined a priori. By comparing both the standard data and a special version of MOPITT data retrieved using the ULIRS a priori for CO, it is shown that standard intercomparisons of CO are strongly affected by the differing a priori data of the retrievals, and by the differing sensitivities of the two instruments. In particular, the differing a priori profiles for MOPITT V3 and V4 data result in systematic retrieved profile changes as expected. An application of averaging kernels is used to derive a difference quantity which is much less affected by smoothing error, and hence more sensitive to systematic error. These conclusions are confirmed by simulations with model profiles for the same region. This technique is used to show that for the data that has been processed the systematic bias between MOPITT V4 and ULIRS IASI data, at MOPITT vertical resolution, is less than 7 % for the comparison data set, and on average appears to be less than 4 %. The results of this study indicate that intercomparisons of satellite data sets with low vertical resolution should ideally be performed with: retrievals using a common a priori appropriate to the geographic region studied; the application of averaging kernels to compute difference quantities with reduced a priori influence; and a comparison with simulated differences using model profiles for the target gas in the region.
Ito, A. (2011), Mega fire emissions in Siberia: potential supply of bioavailable iron  from forests to the ocean, Biogeosciences, 8(6), 1679–1697, doi:10.5194/bg-8-1679-2011.
Significant amounts of carbon and nutrients are released to the atmosphere due to large fires in forests. Characterization of the spatial distribution and temporal variation of the intense fire emissions is crucial for assessing the atmospheric loadings of trace gases and aerosols. This paper discusses issues of the representation of forest fires in the estimation of emissions and the application to an atmospheric chemistry transport model (CTM). The potential contribution of forest fires to the deposition of bioavailable iron (Fe) into the ocean is highlighted, with a focus on mega fires in eastern Siberia.  Satellite products of burned area, active fire, and land cover are used to estimate biomass burning emissions in conjunction with a biogeochemical model. Satellite-derived plume height from MISR is used for the injection height of boreal forest fire emissions. This methodology is applied to quantify fire emission rates in each three-dimensional grid location in the high latitude Northern Hemisphere (>30 degrees N latitude) over a 5-yr period from 2001 to 2005. There is large interannual variation in forest burned area during 2001-2005 (13-49 x 10(3) km(2) yr(-1)) which results in a corresponding variation in the annual emissions of carbon monoxide (CO) (14-81 Tg CO yr(-1)). Satellite observations of CO column from MOPITT are used to evaluate the model performance in simulating the spatial distribution and temporal variation of the fire emissions. The model results for CO enhancements due to eastern Siberian fires are in good agreement with MOPITT observations. These validation results suggest that the model using emission rates estimated in this work is able to describe the interannual changes in CO due to intense forest fires.  Bioavailable iron is derived from atmospheric processing of relatively insoluble iron from desert sources by anthropogenic pollutants (mainly sulfuric acid formed from oxidation of SO(2)) and from direct emissions of soluble iron from combustion sources. Emission scenarios for IPCC AR5 report (Intergovernmental Panel on Climate Change; Fifth Assessment Report) suggest that anthropogenic SO(2) emissions are suppressed in the future to improve air quality. In future warmer and drier climate, severe fire years such as 2003 may become more frequent in boreal regions. The fire emission rates estimated in this study are applied to the aerosol chemistry transport model to examine the relative importance of biomass burning sources of soluble iron compared to those from dust sources. The model reveals that extreme fire events contribute to a significant deposition of soluble iron (20-40 %) to downwind regions over the western North Pacific Ocean, compared to the dust sources with no atmospheric processing by acidic species. These results suggest that the supply of nutrients from large forest fires plays a role as a negative biosphere-climate feedback with regards to the ocean fertilization.
Jiang, Z., D. B. A. Jones, M. Kopacz, J. Liu, D. K. Henze, and C. Heald (2011), Quantifying the impact of model errors on top-down estimates of carbon monoxide emissions using satellite observations, J. Geophys. Res.-Atmos., 116(D15), doi:10.1029/2010JD015282. [online] Available from: http://onlinelibrary.wiley.com/doi/10.1029/2010JD015282/abstract .
We conduct inverse analyses of atmospheric CO, using the GEOS-Chem model and observations from the Measurement of Pollution in the Troposphere satellite instrument, to quantify the potential contribution of systematic model errors on top-down source estimates of CO. We assess how the specification of the source of CO from the oxidation of biogenic nonmethane volatile organic compounds (NMVOCs) in the inversion impacts the top-down estimates. Our results show that when the NMVOC source of CO is comparable to or larger than the combustion source, optimizing the CO from NMVOC emissions on larger spatial scales than the combustion emissions could result in significant overadjustment for the a posteriori CO emissions and could lead to negative sources of CO, such as we found for the top-down South American emissions in June. We quantify the impact of aggregation errors on the source estimates, associated with conducting the inversion at a lower resolution than the atmospheric model. We find that aggregating the emissions across spatial scales in which the a priori error in the emissions changes sign could introduce biases exceeding 20% in the flux estimates since the inversion cannot correct the a priori error by uniformly scaling the emissions across the region. We also use the GEOS-3 and GEOS-4 meteorological fields in GEOS-Chem to examine the impact of discrepancies in atmospheric transport and in the atmospheric OH distribution on the source estimates. We find that the differences in the OH distribution and transport fields associated with the GEOS-3 and GEOS-4 products introduce comparably large differences of as much as 20% in the source estimates. Our results indicate that mitigating systematic model error is critical for improving the accuracy of the inferred source estimates.
Kanakidou, M., N. Mihalopoulos, T. Kindap, U. Im, M. Vrekoussis, E. Gerasopoulos, E. Dermitzaki, A. Unal, M. Koçak, K. Markakis, D. Melas, G. Kouvarakis, A. F. Youssef, A. Richter, N. Hatzianastassiou, A. Hilboll, F. Ebojie, F. Wittrock, C. von Savigny, J. P. Burrows, A. Ladstaetter-Weissenmayer, and H. Moubasher (2011), Megacities as hot spots of air pollution in the East Mediterranean, Atmospheric Environment, 45(6), 1223–1235, doi:10.1016/j.atmosenv.2010.11.048.
This paper provides a comprehensive overview of the actual knowledge on the atmospheric pollution sources, transport, transformation and levels in the East Mediterranean. It focuses both on the background atmosphere and on the similarities and differences between the urban areas that exhibited important urbanization the past years: the two megacities Istanbul, Cairo and the Athens extended area. Ground-based observations are combined with satellite data and atmospheric modeling. The overall evaluation pointed out that long and regional range transport of natural and anthropogenic pollution sources have about similar importance with local sources for the background air pollution levels in the area.
Kaskaoutis, D. G., S. K. Kharol, N. Sifakis, P. T. Nastos, A. R. Sharma, K. V. S. Badarinath, and H. D. Kambezidis (2011), Satellite monitoring of the biomass-burning aerosols during the wildfires of August 2007 in Greece: Climate implications, Atmospheric Environment, 45(3), 716–726, doi:10.1016/j.atmosenv.2010.09.043.
Biomass burning and associated emissions of aerosols into the atmosphere play a vital role in atmospheric composition and climate change. During summer of 2007, Greece faced the worst natural disaster recorded in recent decades in terms of human losses, number of fire outbreaks and extent of the estimated burned area (more than 12% of the total forested areas in Greece). The present study aims at analyzing the impact of these fire events in western Peloponnese on atmospheric aerosol concentrations using satellite data. MODIS-derived Aerosol Optical Depth (AOD), effective radius, Ångström exponent, mass concentration, cloud-condensation nuclei (CCN) and OMI Aerosol Index (AI), single scattering albedo, absorption and extinction optical depths were analyzed. MODIS data showed smoke plumes traversing thousands of kilometers southwards influencing the central Mediterranean as well as the north African coastal regions. These thick smoke plumes dramatically affected AOD and aerosol-mass concentrations over the region and altered the microphysical aerosol properties, such as the effective radius and absorption coefficient. Model calculations suggested that the shortwave radiation at the ground was reduced by ∼50 Wm2, while that at the top of the atmosphere was reduced by ∼20 Wm2 resulting in atmospheric heating of ∼30 Wm2 over the areas affected by the smoke plumes.
Konovalov, I. B., M. Beekmann, I. N. Kuznetsova, A. Yurova, and A. M. Zvyagintsev (2011), Atmospheric impacts of the 2010 Russian wildfires: integrating modelling and measurements of an extreme air pollution episode in the Moscow region, Atmos. Chem. Phys., 11(19), 10031–10056, doi:10.5194/acp-11-10031-2011.
Numerous wildfires provoked by an unprecedented intensive heat wave caused continuous episodes of extreme air pollution in several Russian cities and densely populated regions, including the Moscow region. This paper analyzes the evolution of the surface concentrations of CO, PM10 and ozone over the Moscow region during the 2010 heat wave by integrating available ground based and satellite measurements with results of a mesoscale model. The CHIMERE chemistry transport model is used and modified to include the wildfire emissions of primary pollutants and the shielding effect of smoke aerosols on photolysis. The wildfire emissions are derived from satellite measurements of the fire radiative power and are optimized by assimilating data of ground measurements of carbon monoxide (CO) and particulate matter (PM10) into the model. It is demonstrated that the optimized simulations reproduce independent observations, which were withheld during the optimisation procedure, quite adequately (specifically, the correlation coefficient of daily time series of CO and PM10 exceeds 0.8) and that inclusion of the fire emissions into the model significantly improves its performance. The model results show that wildfires are the principal factor causing the observed air pollution episode associated with the extremely high levels of daily mean CO and PM10 concentrations (up to 10 mg m-3 and 700 μg m-3 in the averages over available monitoring sites, respectively), although accumulation of anthropogenic pollution was also favoured by a stagnant meteorological situation. Indeed, ozone concentrations were simulated to be episodically very large (>400 μg m-3) even when fire emissions were omitted in the model. It was found that fire emissions increased ozone production by providing precursors for ozone formation (mainly VOC), but also inhibited the photochemistry by absorbing and scattering solar radiation. In contrast, diagnostic model runs indicate that ozone concentrations could reach very high values even without fire emissions which provide ”fuel” for ozone formation, but, at the same time, inhibit it as a result of absorption and scattering of solar radiation by smoke aerosols. A comparison of MOPITT CO measurements and corresponding simulations indicates that the observed episodes of extreme air pollution in Moscow were only a part of a very strong perturbation of the atmospheric composition, caused by wildfires, over European Russia. It is estimated that 2010 fires in this region emitted ∼10 Tg CO, thus more than 85% of the total annual anthropogenic CO emissions. About 30% of total CO fire emissions in European Russia are identified as emissions from peat fires.
Li, L., and Y. Liu (2011), Space-borne and ground observations of the characteristics of CO pollution in Beijing, 2000–2010, Atmospheric Environment, 45(14), 2367–2372, doi:10.1016/j.atmosenv.2011.02.026.
Both the long-term and short-term variability of carbon monoxide (CO) pollution in Beijing metropolitan area, China are studied with 11 years of MOPITT observations and 10 years of ground measurements. The impact of the 2008 Beijing Olympic Games on regional air quality is also examined. MOPITT CO columns exhibit different temporal patterns from ground CO concentration measurements. MOPITT CO column in August has gradually increased from 2000 to 2007, even though ground level CO concentrations have significantly decreased due to continued local air pollution control effort. Both CO columns and ground CO concentrations were reduced due to strict albeit temporary emissions control measures from July to September 2008 to support the Beijing Olympic Games. However, the reduction of total CO columns (∼13%) was less pronounced than ground CO concentration (∼44%), indicating that local emission control effort was partially offset by the continuously deteriorating regional air quality. In addition, MOPITT CO mixing ratio profiles indicate a significant regional pattern at higher altitudes. CO total columns after 2008 show an overall increasing trend, in contrast to the decreasing trend observed in ground measurements.
Liu, C., S. Beirle, T. Butler, J. Liu, P. Hoor, P. Jöckel, M. Penning de Vries, A. Pozzer, C. Frankenberg, M. G. Lawrence, J. Lelieveld, U. Platt, and T. Wagner (2011), Application of SCIAMACHY and MOPITT CO total column measurements to evaluate model results over biomass burning regions and Eastern China, Atmos. Chem. Phys., 11(12), 6083–6114, doi:10.5194/acp-11-6083-2011.
We developed a new CO vertical column density product from near IR observations of the SCIAMACHY instrument onboard ENVISAT. For the correction of a temporally and spatially variable offset of the CO vertical column densities we apply a normalisation procedure based on coincident MOPITT (version 4) observations over the oceans. The resulting normalised SCIAMACHY CO data is well suited for the investigation of the CO distribution over continents, where important emission sources are located. We use only SCIAMACHY observations for effective cloud fractions below 20 %. Since the remaining effects of clouds can still be large (up to 100 %), we applied a cloud correction scheme which explicitly considers the cloud fraction, cloud top height and surface albedo of individual observations. The normalisation procedure using MOPITT data and the cloud correction substantially improve the agreement with independent data sets. We compared our new SCIAMACHY CO data set, and also observations from the MOPITT instrument, to the results from three global atmospheric chemistry models (MATCH, EMAC at low and high resolution, and GEOS-Chem); the focus of this comparison is on regions with strong CO emissions (from biomass burning or anthropogenic sources). The comparison indicates that over most of these regions the seasonal cycle is generally captured well but the simulated CO vertical column densities are systematically smaller than those from the satellite observations, in particular with respect to SCIAMACHY observations. Because SCIAMACHY is more sensitive to the lowest part of the atmosphere compared to MOPITT, this indicates that especially close to the surface the model simulations systematically underestimate the true atmospheric CO concentrations, probably caused by an underestimation of CO emissions by current emission inventories. For some biomass burning regions, however, such as Central Africa in July-August, model results are also found to be higher than the satellite observations.
McMillan, W. W., K. D. Evans, C. D. Barnet, E. S. Maddy, G. W. Sachse, and G. S. Diskin (2011), Validating the AIRS Version 5 CO Retrieval With DACOM In Situ  Measurements During INTEX-A and -B, IEEE Trans. Geosci. Remote Sensing, 49(7), 2802–2813, doi:10.1109/TGRS.2011.2106505.
Herein we provide a description of the atmospheric infrared sounder (AIRS) version 5 (v5) carbon monoxide (CO) retrieval algorithm and its validation with the DACOM in situ measurements during the INTEX-A and -B campaigns. All standard and support products in the AIRS v5 CO retrieval algorithm are documented. Building on prior publications, we describe the convolution of in situ measurements with the AIRS v5 CO averaging kernel and first-guess CO profile as required for proper validation. Validation is accomplished through comparison of AIRS CO retrievals with convolved in situ CO profiles acquired during the NASA Intercontinental Chemical Transport Experiments (INTEX) in 2004 and 2006. From 143 profiles in the northern mid-latitudes during these two experiments, we find AIRS v5 CO retrievals are biased high by 6%-10% between 900 and 300 hPa with a root-mean-square error of 8%-12%. No significant differences were found between validation using spiral profiles coincident with AIRS overpasses and in-transit profiles under the satellite track but up to 13 h off in time. Similarly, no significant differences in validation results were found for ocean versus land, day versus night, or with respect to retrieved cloud top pressure or cloud fraction.
Mu, M., J. T. Randerson, G. R. van der Werf, L. Giglio, P. Kasibhatla, D. Morton, G. J. Collatz, R. S. DeFries, E. J. Hyer, E. M. Prins, D. W. T. Griffith, D. Wunch, G. C. Toon, V. Sherlock, and P. O. Wennberg (2011), Daily and 3-hourly variability in global fire emissions and consequences for atmospheric model predictions of carbon monoxide, Journal of Geophysical Research: Atmospheres, 116(D24), n/a–n/a, doi:10.1029/2011JD016245.
Attribution of the causes of atmospheric trace gas and aerosol variability often requires the use of high resolution time series of anthropogenic and natural emissions inventories. Here we developed an approach for representing synoptic- and diurnal-scale temporal variability in fire emissions for the Global Fire Emissions Database version 3 (GFED3). We disaggregated monthly GFED3 emissions during 2003–2009 to a daily time step using Moderate Resolution Imaging Spectroradiometer (MODIS)-derived measurements of active fires from Terra and Aqua satellites. In parallel, mean diurnal cycles were constructed from Geostationary Operational Environmental Satellite (GOES) Wildfire Automated Biomass Burning Algorithm (WF_ABBA) active fire observations. Daily variability in fires varied considerably across different biomes, with short but intense periods of daily emissions in boreal ecosystems and lower intensity (but more continuous) periods of burning in savannas. These patterns were consistent with earlier field and modeling work characterizing fire behavior dynamics in different ecosystems. On diurnal timescales, our analysis of the GOES WF_ABBA active fires indicated that fires in savannas, grasslands, and croplands occurred earlier in the day as compared to fires in nearby forests. Comparison with Total Carbon Column Observing Network (TCCON) and Measurements of Pollution in the Troposphere (MOPITT) column CO observations provided evidence that including daily variability in emissions moderately improved atmospheric model simulations, particularly during the fire season and near regions with high levels of biomass burning. The high temporal resolution estimates of fire emissions developed here may ultimately reduce uncertainties related to fire contributions to atmospheric trace gases and aerosols. Important future directions include reconciling top-down and bottom up estimates of fire radiative power and integrating burned area and active fire time series from multiple satellite sensors to improve daily emissions estimates.
Mukherjee, C., P. S. Kasibhatla, and M. West (2011), Bayesian statistical modeling of spatially correlated error structure in atmospheric tracer inverse analysis, Atmos. Chem. Phys., 11(11), 5365–5382, doi:10.5194/acp-11-5365-2011.
We present and discuss the use of Bayesian modeling and computational methods for atmospheric chemistry inverse analyses that incorporate evaluation of spatial structure in model-data residuals. Motivated by problems of refining bottom-up estimates of source/sink fluxes of trace gas and aerosols based on satellite retrievals of atmospheric chemical concentrations, we address the need for formal modeling of spatial residual error structure in global scale inversion models. We do this using analytically and computationally tractable conditional autoregressive (CAR) spatial models as components of a global inversion framework. We develop Markov chain Monte Carlo methods to explore and fit these spatial structures in an overall statistical framework that simultaneously estimates source fluxes. Additional aspects of the study extend the statistical framework to utilize priors on source fluxes in a physically realistic manner, and to formally address and deal with missing data in satellite retrievals. We demonstrate the analysis in the context of inferring carbon monoxide (CO) sources constrained by satellite retrievals of column CO from the Measurement of Pollution in the Troposphere (MOPITT) instrument on the TERRA satellite, paying special attention to evaluating performance of the inverse approach using various statistical diagnostic metrics. This is developed using synthetic data generated to resemble MOPITT data to define a proof-of-concept and model assessment, and then in analysis of real MOPITT data. These studies demonstrate the ability of these simple spatial models to substantially improve over standard non-spatial models in terms of statistical fit, ability to recover sources in synthetic examples, and predictive match with real data.
Nair, P. R., L. M. David, I. A. Girach, and K. Susan George (2011), Ozone in the marine boundary layer of Bay of Bengal during post-winter period: Spatial pattern and role of meteorology, Atmospheric Environment, 45(27), 4671–4681, doi:10.1016/j.atmosenv.2011.05.040.
Ozone measurements were carried out in the marine environment of the Bay of Bengal during the post-winter months of March–April 2006, as part of the Integrated Campaign for Aerosols, gases and Radiation Budget. The ozone mixing ratio was found to be high over the northern/head BoB with a mean value of 27 ± 3 ppb and minimum over the mid-BoB with 12 ± 3 ppb. The spatial distribution was closely associated with the airflow pattern, airmass back trajectories and the boundary layer height. In this marine environment, meteorology, in particular, the water vapour content also played a significant role in governing the diurnal pattern of ozone in addition to photochemistry. Vertical transport is also partially responsible for the high ozone over the head BoB. The diurnal patterns were simulated using the chemical box model. The spatial map of marine boundary layer ozone was compared with that of tropospheric column ozone, NO2 and CO.
Nara, H., H. Tanimoto, Y. Nojiri, H. Mukai, J. Zeng, Y. Tohjima, and T. Machida (2011), CO emissions from biomass burning in South-east Asia in the 2006 El Nino  year: shipboard and AIRS satellite observations, Environ. Chem., 8(2), 213–223, doi:10.1071/EN10113.
Biomass burning is often associated with climate oscillations. For example, biomass burning in South-east Asia is strongly linked to El Nino-southern oscillation activity. During October and November of the 2006 El Nino year, a substantial increase in CO mixing ratios was detected over the Western tropical Pacific Ocean by shipboard observations routinely operated between Japan and Australia and New Zealand. Combining in-situ measurements, satellite observations, and an air trajectory model simulation, two high CO episodes were identified originating from biomass burning in Borneo, Sumatra, New Guinea, and Northern Australia. Between 15 degrees N and the Equator, marked CO enhancements were encountered associated with a significant correlation between CO and CO(2) and between CO and O(3). The Delta CO/Delta CO(2) ratio observed in the fire plume was considerably high (171 ppbv ppmv(-1)), suggesting substantial contributions from peat soil burning in Indonesia. In contrast, the Delta O(3)/Delta CO ratio was only 0.05 ppbv ppbv (1), indicating that net photochemical production of O(3) in the plume was negligible during long-range transport in the lower troposphere over the Western tropical North Pacific.
Ott, L., S. Pawson, and J. Bacmeister (2011), An analysis of the impact of convective parameter sensitivity on simulated global atmospheric CO distributions, Journal of Geophysical Research: Atmospheres, 116(D21), n/a–n/a, doi:10.1029/2011JD016077.
In an effort to better understand how uncertainty in simulated convection propagates into simulations of global trace gas distributions, we have constructed an eight-member ensemble of simulations using NASA’s Goddard Earth Observing System Version 5 (GEOS-5) general circulation model (GCM). The ensemble was created by perturbing parameters in the model’s moist physics schemes found to strongly influence the magnitude of convective mass flux. Globally, ensemble spreads in column CO are typically small (less than 4% of the mean column value) and, in many areas, are not significantly different from internal model variability. The largest ensemble spreads are found near source regions and outflow pathways. At the majority of remote surface monitoring sites, the annual mean ensemble spread is less than 5%, indicating that these locations, which are often the basis of inversion studies, are relatively insensitive to uncertainty in the representation of convection. We also examine in greater detail two simulations in which the magnitude of convective mass flux is significantly altered. Changes to convective parameters strongly influence grid-scale vertical and turbulent transport processes in addition to convective mass flux. Despite large differences in the magnitude of convective mass fluxes, this compensating behavior by other model processes results in comparable atmospheric residence times in the two simulations and largely similar global CO distributions. The results indicate that convective mass flux is strongly related to other vertical transport processes in a GCM and cannot be viewed as entirely separate. Future studies of the role of convective transport need to consider the relationship between convective and total mass flux.
Parker, R. J., J. J. Remedios, D. P. Moore, and V. P. Kanawade (2011), Acetylene C2H 2 retrievals from MIPAS data and  regions of enhanced upper tropospheric concentrations in August 2003, Atmos. Chem. Phys., 11(19), 10243–10257, doi:10.5194/acp-11-10243-2011.
Acetylene (C2H2) volume mixing ratios (VMRs) have been successfully retrieved from the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) Level 1B radiances during August 2003, providing the first global map of such data and ratios to CO in the literature. The data presented here contain most information between 300 hPa and 100 hPa with systematic errors less than 10% at the upper levels. Random errors per point are less than 15% at lower levels and are closer to 30% at 100 hPa.
Pfister, G. G., J. Avise, C. Wiedinmyer, D. P. Edwards, L. K. Emmons, G. D. Diskin, J. Podolske, and A. Wisthaler (2011), CO source contribution analysis for California during ARCTAS-CARB, Atmos. Chem. Phys., 11(15), 7515–7532, doi:10.5194/acp-11-7515-2011.
Air pollution is of concern in many parts of California and is impacted by both local emissions and also by pollution inflow from the North Pacific Ocean. In this study, we use the regional chemical transport model WRF-Chem V3.2 together with the global Model for OZone and Related Chemical Tracers to examine the CO budget over California. We include model CO tracers for different emission sources in the models, which allow estimation of the relative importance of local sources versus pollution inflow on the distribution of CO at the surface and in the free troposphere. The focus of our study is on the 15 June-15 July 2008 time period, which coincides with the aircraft deployment of the NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission over California. Model simulations are evaluated using these aircraft observations as well as satellite retrievals and surface observations of CO. Evaluation results show that the model overall predicts the observed CO fields well, but points towards an underestimate of CO from the fires in Northern California, which had a strong influence during the study period, and towards a slight overestimate of CO from pollution inflow and local anthropogenic sources. The analysis of the CO budget over California reveals that inflow of CO explains on average 99 +/- 11 ppbV of surface CO during the study period, compared to 61 +/- 95 ppbV for local anthropogenic direct emissions of CO and 84 +/- 194 ppbV for fires. In the free troposphere, the average CO contributions are estimated as 96 +/- 7 ppbV for CO inflow, 8 +/- 9 ppbV for CO from local anthropogenic sources and 18 +/- 13 ppbV for CO from fires. Accounting for the low bias in the CO fire emission inventory, the fire impact during the study period might have been up to a factor 4 higher than the given estimates.
Pommrich, R., R. Müller, J.-U. Grooß, P. Konopka, G. Günther, H.-C. Pumphrey, S. Viciani, F. D’Amato, and M. Riese (2011), Carbon monoxide as a tracer for tropical troposphere to stratosphere transport in the Chemical Lagrangian Model of the Stratosphere (CLaMS), Geoscientific Model Development Discussions, 4(2), 1185–1211, doi:10.5194/gmdd-4-1185-2011.
Variations in the mixing ratio of trace gases of tropospheric origin entering the stratosphere in the tropics are of interest for assessing both troposphere to stratosphere transport fluxes in the tropics and the impact on the composition of the tropical lower stratosphere of quasi-horizontal in-mixing into the tropical tropopause layer from the mid-latitude stratosphere. Here, we present a simplified chemistry scheme for the Chemical Lagrangian Model of the Stratosphere (CLaMS) for the simulation, at comparatively low numerical cost, of CO, ozone, and long-lived trace substances (CH4, N2O, CCl3F, and CO2) in the lower tropical stratosphere. The boundary conditions at the ground are represented for the long-lived trace substances CH4, N2O, CCl3F, and CO2 based on ground-based measurements. The boundary condition for CO in the free troposphere is deduced from MOPITT measurements. We find that the zonally averaged tropical CO anomaly patterns simulated by this model version of CLaMS are in good agreement with observations. The introduction of a new scheme in the ECMWF integrated forecast system (Tompkins et al., 2007) for the ice supersaturation after September 2006, results in a somewhat less good agreement between observed and simulated CO patterns in the tropical lower stratosphere after this date.
Sitnov, S. A. (2011a), Aerosol optical thickness and the total carbon monoxide content over the  European Russia territory in the 2010 summer period of mass fires:  Interrelation between the variation in pollutants and meteorological  parameters, Izv. Atmos. Ocean. Phys., 47(6), 714–728, doi:10.1134/S0001433811060156.
The spatial and temporal variabilities of the aerosol optical thickness (AOT) and the total carbon monoxide content (CO) in the period of development and weakening of mass forest and peatbog fires in the European Russia territory (ERT) in the summer of 2010 are investigated from data of the AOT and CO satellite observations. The intensities of aerosol and CO emissions in the period of mass fires and the ratio of the emission factors of aerosol particles and CO are estimated on the basis of calculations of the smoke and CO masses over the ERT. The interrelation between variations in the levels of the regional pollution by combustion products and the variability of meteorological parameters is investigated. Various aspects of the manifestation of radiation effects of aerosols are discussed. The synchronization of weekly signals of the AOT, CO, and meteorological parameters in the period of mass fires is noted.
Sitnov, S. A. (2011b), Analysis of satellite observations of aerosol optical properties and gaseous species over Central District of Russian Federation in the period of abnormally high, summer temperature and mass wild fires in 2010, Optika Atmosfery i Okeana, 24(7), 572–581.
The optical properties of aerosol ( tau sub(0.55), omega sub(o.50), and absorbing aerosol index) and the contents of atmospheric gaseous species (CO, NO sub(2), SO sub(2), CH sub(2)O, O sub(3), H sub(2)O), obtained with the help of the satellite instruments MODIS, MOPITT, and OMI over the territory of the central region of Russian Federation (52-59 degree N, 29-45 degree E) in the period from April till September 2010 are analyzed. Abnormal increasing of temperature and the changes in atmospheric composition due to the forest and peatbog fires are clearly revealed in the interrelated changes of most of the atmospheric parameters. In the period from the middle of July till August, 7, the regionally averaged value of tau 0.55 was icreased more than by 20 times (from 0.09 to 2.12) and the CO total column was increased more than twice (from 1.9 times 10 super(18) to 4.0 times 10 super(18) molec. times cm super(-2)), while in July-August the tropospheric NO sub(2) content in 2010 was 65% higher than in 2009. The spatial-temporal evolution of aerosol characteristics and gaseous species before, during, and after mass wild fires is studied, as well as radiation effects of smoke are analyzed.
Sitnov, S. A. (2011c), Satellite monitoring of atmospheric gaseous species and optical characteristics of atmospheric aerosol over the European part of Russia in April–September 2010, Dokl. Earth Sc., 437(1), 368–373, doi:10.1134/S1028334X11030081.
The results of satellite monitoring of carbon monoxide (CO₂), nitrogen dioxide (NO₂), formaldehyde (HCNO), water vapor (H₂O), and ozone (O₃), aerosol optical thickness (AOT) and Angström parameter (α) over the European part of Russia in April-September 2010 are presented. The interrelation between the changes of various atmospheric parameters and spatial distributions of atmospheric pollutants during the development of regional weather anomaly and the beginning of massive wildfires that led to smog in the region is analyzed.
Tilmes, S., L. K. Emmons, K. S. Law, G. Ancellet, H. Schlager, J.-D. Paris, H. E. Fuelberg, D. G. Streets, C. Wiedinmyer, G. S. Diskin, Y. Kondo, J. Holloway, J. P. Schwarz, J. R. Spackman, T. Campos, P. Nédélec, and M. V. Panchenko (2011), Source contributions to Northern Hemisphere CO and black carbon during spring and summer 2008 from POLARCAT and START08/preHIPPO observations and MOZART-4, Atmospheric Chemistry and Physics Discussions, 11(2), 5935–5983, doi:10.5194/acpd-11-5935-2011.
Anthropogenic pollution and wildfires are main producers of carbon monoxide (CO) and black carbon (BC) in the Northern Hemisphere. High concentrations of these compounds are transported into the Arctic troposphere, influencing the ecosystem in high northern latitudes and the global climate. The global chemical transport model MOZART-4 is used to quantify the seasonal evolution of the contribution of CO and BC from different source regions in spring and summer 2008 by tagging their emissions. Aircraft observations from the POLARCAT experiments, in particular NASA ARCTAS, NOAA ARCPAC, POLARCAT-France, DLR GRACE and YAK-AEROSIB, as well as the NSF START08/preHIPPO experiments during Spring-Summer 2008 are combined to quantify the representation of simulated tracer characteristics in anthropogenic and fire plumes. In general, the model reproduces CO and BC well. Based on aircraft measurements and FLEXPART back-trajectories, the altitude contribution of emissions coming from different source regions is well captured in the model. Uncertainties of the MOZART-4 model are identified by comparing the data with model results on the flight tracks and using MOPITT satellite observations. Anthropogenic emissions are underestimated by about 10% in high northern latitudes in spring, and shortcomings exist in simulating fire plumes. The remote impact of East-Siberian fire emissions is underestimated for spring, whereas the impact of Southeast Asian fire emissions to mid-latitude CO values is overestimated by the model. In summer, mid-latitude CO values agree well between model and observations, whereas summer high latitude East-Siberian fire emissions in the model are overestimated by 20% in comparison to observations in the region. On the other hand, CO concentrations are underestimated by about 30% over Alaska and Canada at altitudes above 4 km. BC values are overestimated by the model at altitudes above 4 km in summer. Based on MOZART-4, with tagged CO and BC tracers, anthropogenic emissions of Asia, Europe and the US have the largest contribution to the CO and BC in mid- and high latitudes in spring and summer. Southeast Asian, Chinese and Indian fires have a large impact on CO pollution in spring in low latitudes with a maximum between 20° and 30°, whereas Siberian fires contribute largely to the pollution in high latitudes, up to 10% in spring and up to 30% in summer. The largest contributions to BC values in high latitudes are from anthropogenic emissions (about 70%). CO and BC have larger mass loadings in April than in July, as a result of photochemistry and dynamics.
Xu, W. Y., C. S. Zhao, L. Ran, Z. Z. Deng, P. F. Liu, N. Ma, W. L. Lin, X. B. Xu, P. Yan, X. He, J. Yu, W. D. Liang, and L. L. Chen (2011), Characteristics of pollutants and their correlation to meteorological conditions at a suburban site in the North China Plain, Atmos. Chem. Phys., 11(9), 4353–4369, doi:10.5194/acp-11-4353-2011.
North China Plain (NCP) is one of the most densely populated regions in China and has experienced enormous economic growth in the past decades. Its regional trace gas pollution has also become one of the top environmental concerns in China. Measurements of surface trace gases, including O sub(3), NO sub(x), SO sub(2) and CO were carried out within the HaChi (Haze in China) project at Wuqing Meteorology Station, located between 2 mega-cities (Beijing and Tianjin) in the NCP, from 9 July 2009 to 21 January 2010. Detailed statistical analyses were made in order to provide information on the levels of the measured air pollutants and their characteristics. Gaseous air pollutant concentrations were also studied together with meteorological data and satellite data to help us better understand the causes of the observed variations in the trace gases during the field campaign. In comparison to measurements from other rural and background stations in the NCP, relatively high concentrations were detected in Wuqing, presumably due to regional mixing and transport of pollutants. Local meteorology had deterministic impacts on air pollution levels, which have to be accounted for when evaluating other effects on pollutant concentrations. Trace gas concentrations showed strong dependence on wind, providing information on regional pollution characteristics. O sub(3) mixing ratio also showed clear dependencies on temperature and relative humidity.
Yurganov, L. N., V. Rakitin, A. Dzhola, T. August, E. Fokeeva, M. George, G. Gorchakov, E. Grechko, S. Hannon, A. Karpov, L. Ott, E. Semutnikova, R. Shumsky, and L. Strow (2011), Satellite- and ground-based CO total column observations over 2010 Russian fires: accuracy of top-down estimates based on thermal IR satellite data, Atmos. Chem. Phys., 11(15), 7925–7942, doi:10.5194/acp-11-7925-2011.
CO total column data are presented from three space sounders and two ground-based spectrometers in Moscow and its suburbs during the forest and peat fires that occurred in Central Russia in July-August 2010. Also presented are ground-based in situ CO measurements. The Moscow area was strongly impacted by the CO plume from these fires. Concurrent satellite- and ground-based observations were used to quantify the errors of CO top-down emission estimates. On certain days, CO total columns retrieved from the data of the space-based sounders were 2-3 times less than those obtained from the ground-based sun-tracking spectrometers. The depth of the polluted layer over Moscow was estimated using total column measurements compared with CO volume mixing ratios in the surface layer and on the TV tower and found to be around 360 m. The missing CO that is the average difference between the CO total column accurately determined by the ground spectrometers and that retrieved by AIRS, MOPITT, and IASI was determined for the Moscow area between 1.6 and 3.3 × 1018 molec cm-2. These values were extrapolated onto the entire plume; subsequently, the CO burden (total mass) over Russia during the fire event was corrected. A top-down estimate of the total emitted CO, obtained by a simple mass balance model increased by 40-100 % for different sensors due to this correction. Final assessments of total CO emitted by Russian wildfires obtained from different sounders are between 34 and 40 Tg CO during July-August 2010.
Zhang, Y. (2011), Mean global and regional distributions of MOPITT carbon monoxide during 2000–2009 and during ENSO, Atmospheric Environment, 45(6), 1347–1358, doi:10.1016/j.atmosenv.2010.11.044.
The MOPITT (Measurements Of Pollution In The Troposphere) CO measurements over a 10-year period (2000–2009) reveal consistently positive trends on the order of 0.13–0.19 × 1016 mol cm−2 per month in CO total column concentrations over the entire globe and the hemispheres. Two maxima in globally averaged CO concentrations are identified: one in April and one in October, with two minima in July and December. These maxima and minima are attributable to the respective maxima and minima in CO concentrations over the Northern and Southern Hemispheres. Over the Tropics, maximum and minimum CO concentrations are noted in October and June, respectively, due primarily to biomass burning.  During El Niño DJF (December–January–February) and JJA (June–July–August), predominantly positive anomalies in CO total column are noted over the entire globe except for the high latitudes of both hemispheres and the central part of the South America where negative anomalies are identified. La Niña DJF and JJA are largely opposite to El Niño DJF and JJA in CO total column anomalies. Negative (positive) anomalies in CO total column tend to be associated with wet (dry) anomalies in precipitation over the major polluted areas during ENSO. It is suggested that changes in the atmospheric circulations during ENSO either enhance or weaken precipitation systems with the associated precipitation modulating CO total column. The correspondence between anomalies in CO total column and anomalies in Terra MODIS fire pixels during ENSO is rather poor over many parts of the world.

2010

Anu Rani Sharma, Shailesh Kumar Kharol, K. V. S. Badarinath, and Darshan Singh (2010), Impact of agriculture crop residue burning on atmospheric aerosol loading – a study over Punjab State, India, Ann. Geophys., 28(2), 367–379, doi:10.5194/angeo-28-367-2010.
The present study deals with the impact of agriculture crop residue burning on aerosol properties during October 2006 and 2007 over Punjab State, India using ground based measurements and multi-satellite data. Spectral aerosol optical depth (AOD) and Ångström exponent (α) values exhibited larger day to day variation during crop residue burning period. The monthly mean Ångström exponent “α” and turbidity parameter “β” values during October 2007 were 1.31±0.31 and 0.36±0.21, respectively. The higher values of “α” and “β” suggest turbid atmospheric conditions with increase in fine mode aerosols over the region during crop residue burning period. AURA-OMI derived Aerosol Index (AI) and Nitrogen dioxide (NO2) showed higher values over the study region during October 2007 compared to October 2006 suggesting enhanced atmospheric pollution associated with agriculture crop residue burning.
Arellano, A. F., P. G. Hess, D. P. Edwards, and D. Baumgardner (2010), Constraints on black carbon aerosol distribution from Measurement of Pollution in the Troposphere (MOPITT) CO, Geophysical Research Letters, 37(17), 17801, doi:10.1029/2010GL044416.
We present an approach to constrain simulated atmospheric black carbon (BC) using carbon monoxide (CO) observations. The approach uses: (1) the Community Atmosphere Model with Chemistry to simulate the evolution of BC and CO within an ensemble of model simulations; (2) satellite CO retrievals from the MOPITT/Terra instrument to assimilate observed CO into these simulations; (3) the derived sensitivity of BC to CO within these simulations to correct the simulated BC distributions. We demonstrate the performance of this approach through model experiments with and without the BC corrections during the period coinciding with the Intercontinental Chemical Transport Experiment (INTEX-B). Our results show significant improvements (∼50%) in median BC profiles using constraints from MOPITT, based on comparisons with INTEX-B measurements. We find that assimilating MOPITT CO provides considerable impact on simulated BC concentrations, especially over source regions. This approach offers an opportunity to augment our current ability to predict BC distributions.
Beirle, S., H. Huntrieser, and T. Wagner (2010), Direct satellite observation of lightning-produced NOx, Atmos. Chem. Phys., 10(22), 10965–10986, doi:10.5194/acp-10-10965-2010.
Lightning is an important source of NO sub(x) in the free troposphere, especially in the tropics, with strong impact on ozone production. However, estimates of lightning NO sub(x) (LNO sub(x)) production efficiency (LNO sub(x) per flash) are still quite uncertain. In this study we present a systematic analysis of NO sub(2) column densities from SCIAMACHY measurements over active thunderstorms, as detected by the World-Wide Lightning Location Network (WWLLN), where the WWLLN detection efficiency was estimated using the flash climatology of the satellite lightning sensors LIS/OTD. Only events with high lightning activity are considered, where corrected WWLLN flash rate densities inside the satellite pixel within the last hour are above 1 /km super(2)/h. For typical SCIAMACHY ground pixels of 30 60 km super(2), this threshold corresponds to 1800 flashes over the last hour, which, for literature estimates of lightning NO sub(x) production, should result in clearly enhanced NO sub(2) column densities. From 2004-2008, we find 287 coincidences of SCIAMACHY measurements and high WWLLN flash rate densities. For some of these events, a clear enhancement of column densities of NO sub(2) could be observed, indeed. But overall, the measured column densities are below the expected values by more than one order of magnitude, and in most of the cases, no enhanced NO sub(2) could be found at all. Our results are in contradiction to the currently accepted range of LNO sub(x) production per flash of 15 (2-40)10 super(25) molec/flash. This probably partly results from the specific conditions for the events under investigation, i.e. events of high lightning activity in the morning (local time) and mostly (for 162 out of 287 events) over ocean. Within the detected coincidences, the highest NO sub(2) column densities were observed around the US Eastcoast. This might be partly due to interference with ground sources of NO sub(x) being uplifted by the convective systems. However, it could also indicate that flashes in this region are particularly productive. We conclude that current estimates of LNO sub(x) production might be biased high for two reasons. First, we observe a high variability of NO sub(2) for coincident lightning events. This high variability can easily cause a publication bias, since studies reporting on high NO sub(x) production have likely been published, while studies finding no or low amounts of NO sub(x) might have been rejected as errorneous or not significant. Second, many estimates of LNO sub(x) production in literature have been performed over the US, which is probably not representative for global lightning.
Bian, H., M. Chin, S. R. Kawa, H. Yu, T. Diehl, and T. Kucsera (2010), Multiscale carbon monoxide and aerosol correlations from satellite measurements and the GOCART model: Implication for emissions and atmospheric evolution, Journal of Geophysical Research: Atmospheres, 115(D7), n/a–n/a, doi:10.1029/2009JD012781.
Regional correlations of CO and aerosol on different time scales provide information on their sources, lifetimes, and transport pathways. We examine regional and global column CO and fine-mode aerosol optical depth (AODf) correlations from daily to seasonal scales using 7 years (2000–2006) of satellite observations from the Measurement of Pollution in the Troposphere and the Moderate Resolution Imaging Spectroradiometer and model simulations from the Goddard Chemistry Aerosol Radiative Transport model. Our analyses indicate that, globally, column CO and AODf have similar spatial distributions due to their common source locations, although CO is more spatially dispersed because of its longer lifetime. However, temporal CO-AODf correlations differ substantially over different timescales and different regions. On daily to synoptic scales CO and AODf have a positive correlation over the industrial and biomass burning source regions owing to the covariance of emissions and coherent dynamic transport. No such correlation is seen in remote regions because of the diverging influence of mixing and chemical processes during longer-range transport. On the seasonal scale in the Northern Hemisphere, CO and AODf are out of phase by 2–4 months. This phase lag is caused by photochemical production of sulfate, which is the major component of fine-mode aerosol in the Northern Hemisphere, and photochemical destruction of CO in reaction with OH (both at maximum in the summer and at minimum in the winter), together with the seasonality of fine-mode dust, which peaks in the boreal spring season. In the Southern Hemisphere tropics and subtropics, however, CO and AODf are generally in-phase because the variability is dominated by direct release from biomass burning emissions.
Choi, Y., G. Osterman, A. Eldering, Y. Wang, and E. Edgerton (2010), Understanding the contributions of anthropogenic and biogenic sources to CO enhancements and outflow observed over North America and the western Atlantic Ocean by TES and MOPITT, Atmospheric Environment, 44(16), 2033–2042, doi:10.1016/j.atmosenv.2010.01.029.
We investigate the effects of anthropogenic and biogenic sources on tropospheric CO enhancements and outflow over North America and the Atlantic during July August 2006, the 3rd warmest summer on record. The analysis is performed using the 3D Regional chEmical trAnsport Model (REAM), satellite data from TES on the Aura satellite, MOPITT on the Terra satellite and surface monitor data from the SEARCH network. The satellite measurements of CO provide insight into the location of regional CO enhancements along with the ability to resolve vertical features. Satellite and surface monitor data are used to compare with REAM, illustrating model’s ability to reproduce observed CO concentrations. The REAM model used in this study features CO emissions reduced by 50% from the 1999 EPA NEI and biogenic VOC emissions scaled by EPA-observed isoprene concentrations (20% reduction). The REAM simulations show large variations in surface CO, lower tropospheric CO and column CO, which are also observed by the surface observations and satellite data. Over the US, during July August 2006, the model estimates monthly CO production from anthropogenic sources (5.3 and 51 Tg CO) is generally larger than biogenic sources (4.3 and 3.5 Tg CO). However, the model shows that for very warm days, biogenic sources produce as much CO as anthropogenic sources, a result of increased biogenic production due to warmer temperatures. The satellite data show CO outflow occurs along the East Coast of the US and Canada in July and is more broadly distributed over the Atlantic in August. REAM results show the longitudinally exported CO enhancements from anthropogenic sources (3.3 and 3.9 Tg CO) are larger than biogenic sources (2 8 and 2.7 Tg CO) along the eastern boundary of REAM for July August 2006 We show that when compared with the impacts of both sources on increasing tropospheric CO exports, the relative Impacts in August are greater than in July because of preferable outflow transport (C) 2010 Elsevier Ltd. All rights reserved.
Claeyman, M., J.-L. Attié, L. El Amraoui, D. Cariolle, V.-H. Peuch, H. Teyssèdre, B. Josse, P. Ricaud, S. Massart, A. Piacentini, J.-P. Cammas, N. J. Livesey, H. C. Pumphrey, and D. P. Edwards (2010), A linear CO chemistry parameterization in a chemistry-transport model: evaluation and application to data assimilation, Atmos. Chem. Phys., 10(13), 6097–6115, doi:10.5194/acp-10-6097-2010.
This paper presents an evaluation of a new linear parameterization valid for the troposphere and the stratosphere, based on a first order approximation of the carbon monoxide (CO) continuity equation. This linear scheme (hereinafter noted LINCO) has been implemented in the 3-D Chemical Transport Model (CTM) MOCAGE (MOdele de Chimie Atmospherique Grande Echelle). First, a one and a half years of LINCO simulation has been compared to output obtained from a detailed chemical scheme output. The mean differences between both schemes are about +/- 25 ppbv (part per billion by volume) or 15% in the troposphere and +/- 10 ppbv or 100% in the stratosphere. Second, LINCO has been compared to diverse observations from satellite instruments covering the troposphere (Measurements Of Pollution In The Troposphere: MOPITT) and the stratosphere (Microwave Limb Sounder: MLS) and also from aircraft (Measurements of ozone and water vapour by Airbus in-service aircraft: MOZAIC programme) mostly flying in the upper troposphere and lower stratosphere (UTLS). In the troposphere, the LINCO seasonal variations as well as the vertical and horizontal distributions are quite close to MOPITT CO observations. However, a bias of similar to -40 ppbv is observed at 700 hPa between LINCO and MOPITT. In the stratosphere, MLS and LINCO present similar large-scale patterns, except over the poles where the CO concentration is underestimated by the model. In the UTLS, LINCO presents small biases less than 2% compared to independent MOZAIC profiles. Third, we assimilated MOPITT CO using a variational 3D-FGAT (First Guess at Appropriate Time) method in conjunction with MOCAGE for a long run of one and a half years. The data assimilation greatly improves the vertical CO distribution in the troposphere from 700 to 350 hPa compared to independent MOZAIC profiles. At 146 hPa, the assimilated CO distribution is also improved compared to MLS observations by reducing the bias up to a factor of 2 in the tropics. This study confirms that the linear scheme is able to simulate reasonably well the CO distribution in the troposphere and in the lower stratosphere. Therefore, the low computing cost of the linear scheme opens new perspectives to make free runs and CO data assimilation runs at high resolution and over periods of several years.
Deeter, M. N., D. P. Edwards, J. C. Gille, L. K. Emmons, G. Francis, S.-P. Ho, D. Mao, D. Masters, H. Worden, J. R. Drummond, and P. C. Novelli (2010), The MOPITT version 4 CO product: Algorithm enhancements, validation, and  long-term stability, J. Geophys. Res.-Atmos., 115(D7), doi:10.1029/2009JD013005. [online] Available from: http://onlinelibrary.wiley.com/doi/10.1029/2009JD013005/abstract .
Vertical profiles of carbon monoxide (CO) concentration and corresponding total column values derived from measurements made by the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument are now being processed operationally with the “version 4” (V4) retrieval algorithm. This algorithm exploits the results of analyses of in situ data, chemical transport modeling, and radiative transfer modeling in the MOPITT postlaunch era. Improvements in the V4 product are evident in both clean and polluted conditions. The new products are validated using CO in situ measurements acquired from aircraft from 2000 to 2007. As determined by both retrieval simulations and observations, retrieval bias drift is typically about 1 ppbv/yr for levels in the middle troposphere and about 2 ppbv/yr in the upper troposphere. Retrieval simulations indicate that observed bias drift may be the result of gradual on-orbit changes in the instrument’s modulation cell parameters.
Drummond, J. R., J. Zou, F. Nichitiu, J. Kar, R. Deschambaut, and J. Hackett (2010), A review of 9-year performance and operation of the MOPITT instrument, Advances in Space Research, 45(6), 760–774, doi:10.1016/j.asr.2009.11.019.
The MOPITT (Measurements of Pollution in the Troposphere) instrument has provided more than nine years of global carbon monoxide (CO) measurements on a continuous basis since its launch aboard the Terra Spacecraft on December 18th, 1999. This paper gives an overview of the core sub-system performance and major issues of the in-flight instrument over the mission period. Some of the instrument anomalies are also discussed. The major successes are: (1) the concept of using a combination of correlation systems such as Length Modulated Cells (LMCs) and Pressure Modulated Cells (PMCs) to retrieve CO profiles in the troposphere; (2) the redundant design in the instrumentation which was crucial for coping with unexpected in-flight anomalies and for continuing the mission in the case of component failure; (3) the thermal environment on orbit that is so stable that some calibration procedures are not necessary; and (4) the recent production of CO total column retrieved from the MOPITT 2.3 μm channel.
El Amraoui, L., J.-L. Attié, N. Semane, M. Claeyman, V.-H. Peuch, J. Warner, P. Ricaud, J.-P. Cammas, A. Piacentini, B. Josse, D. Cariolle, S. Massart, and H. Bencherif (2010), Midlatitude stratosphere – troposphere exchange as diagnosed by MLS O3 and MOPITT CO assimilated fields, Atmos. Chem. Phys., 10(5), 2175–2194, doi:10.5194/acp-10-2175-2010.
This paper presents a comprehensive characterization of a very deep stratospheric intrusion which occurred over the British Isles on 15 August 2007. The signature of this event is diagnosed using ozonesonde measurements over Lerwick, UK (60.14° N, 1.19° W) and is also well characterized using meteorological analyses from the global operational weather prediction model of Météo-France, ARPEGE. Modelled as well as assimilated fields of both ozone (O3) and carbon monoxide (CO) have been used in order to better document this event. O3 and CO from Aura/MLS and Terra/MOPITT instruments, respectively, are assimilated into the three-dimensional chemical transport model MOCAGE of Météo-France using a variational 3-D-FGAT (First Guess at Appropriate Time) method. The validation of O3 and CO assimilated fields is done using self-consistency diagnostics and by comparison with independent observations such as MOZAIC (O3 and CO), AIRS (CO) and OMI (O3). It particularly shows in the upper troposphere and lower stratosphere region that the assimilated fields are closer to MOZAIC than the free model run. The O3 bias between MOZAIC and the analyses is -11.5 ppbv with a RMS of 22.4 ppbv and a correlation coefficient of 0.93, whereas between MOZAIC and the free model run, the corresponding values are 33 ppbv, 38.5 ppbv and 0.83, respectively. In the same way, for CO, the bias, RMS and correlation coefficient between MOZAIC and the analyses are -3.16 ppbv, 13 ppbv and 0.79, respectively, whereas between MOZAIC and the free model they are 6.3 ppbv, 16.6 ppbv and 0.71, respectively. The paper also presents a demonstration of the capability of O3 and CO assimilated fields to better describe a stratosphere-troposphere exchange (STE) event in comparison with the free run modelled O3 and CO fields. Although the assimilation of MLS data improves the distribution of O3 above the tropopause compared to the free model run, it is not sufficient to reproduce the STE event well. Assimilated MOPITT CO allows a better qualitative description of the stratospheric intrusion event. The MOPITT CO analyses appear more promising than the MLS O3 analyses in terms of their ability to capture a deep STE event. Therefore, the results of this study open the perspectives for using MOPITT CO in the STE studies.
Elguindi, N., H. Clark, C. Ordóñez, V. Thouret, J. Flemming, O. Stein, V. Huijnen, P. Moinat, A. Inness, V.-H. Peuch, A. Stohl, S. Turquety, G. Athier, J.-P. Cammas, and M. Schultz (2010), Current status of the ability of the GEMS/MACC models to reproduce the tropospheric CO vertical distribution as measured by MOZAIC, Geoscientific Model Development, 3, 501–518, doi:10.5194/gmd-3-501-2010.
Vertical profiles of CO taken from the MOZAIC aircraft database are used to globally evaluate the performance of the GEMS/MACC models, including the ECMWF-Integrated Forecasting System (IFS) model coupled to the CTM MOZART-3 with 4DVAR data assimilation for the year 2004. This study provides a unique opportunity to compare the performance of three offline CTMs (MOZART-3, MOCAGE and TM5) driven by the same meteorology as well as one coupled atmosphere/CTM model run with data assimilation, enabling us to assess the potential gain brought by the combination of online transport and the 4DVAR chemical satellite data assimilation. First we present a global analysis of observed CO seasonal averages and interannual variability for the years 2002-2007. Results show that despite the intense boreal forest fires that occurred during the summer in Alaska and Canada, the year 2004 had comparably lower tropospheric CO concentrations. Next we present a validation of CO estimates produced by the MACC models for 2004, including an assessment of their ability to transport pollutants originating from the Alaskan/Canadian wildfires. In general, all the models tend to underestimate CO. The coupled model and the CTMs perform best in Europe and the US where biases range from 0 to -25% in the free troposphere and from 0 to -50% in the surface and boundary layers (BL). Using the 4DVAR technique to assimilate MOPITT V4 CO significantly reduces biases by up to 50% in most regions. However none of the models, even the IFS-MOZART-3 coupled model with assimilation, are able to reproduce well the CO plumes originating from the Alaskan/Canadian wildfires at downwind locations in the eastern US and Europe. Sensitivity tests reveal that deficiencies in the fire emissions inventory and injection height play a role.
Emmons, L. K., S. Walters, P. G. Hess, J.-F. Lamarque, G. G. Pfister, D. Fillmore, C. Granier, A. Guenther, D. Kinnison, T. Laepple, J. Orlando, X. Tie, G. Tyndall, C. Wiedinmyer, S. L. Baughcum, and S. Kloster (2010), Description and evaluation of the Model for Ozone and Related chemical Tracers, version 4 (MOZART-4), Geoscientific Model Development, 3(1), 43–67, doi:10.5194/gmd-3-43-2010.
The Model for Ozone and Related chemical Tracers, version 4 (MOZART-4) is an offline global chemical transport model particularly suited for studies of the troposphere. The updates of the model from its previous version MOZART-2 are described, including an expansion of the chemical mechanism to include more detailed hydrocarbon chemistry and bulk aerosols. Online calculations of a number of processes, such as dry deposition, emissions of isoprene and monoterpenes and photolysis frequencies, are now included. Results from an eight-year simulation (2000–2007) are presented and evaluated. The MOZART-4 source code and standard input files are available for download from the NCAR Community Data Portal (http://cdp.ucar.edu).
Ghude, S. D., P. S. Kulkarni, G. Beig, S. L. Jain, and B. C. Arya (2010), Global distribution of tropospheric ozone and its precursors: a view from space, Int. J. Remote Sens., 31(2), 485–495, doi:10.1080/01431160902893519.
Satellite-borne tropospheric ozone measurements obtained from the tropospheric ozone residual (TOR) method, CO from the MOPITT (at 850 hPa level) measurements and NO(2) from the SCIAMACHY measurements for the three-year period 2003-2005 have been utilized to examine the distribution of the pollutant sources and long-range transport on a global scale. Elevated tropospheric ozone columns have been observed over regions of high NO2 and CO concentrations in the northern and southern hemispheres. High levels of the tropospheric ozone column have been observed below about 5 degrees S in the vicinity of the biomass burning regions and extend from continents out over the Atlantic during October. The seasonal distribution of tropospheric O(3) and its precursors in the southern hemisphere shows the strong correlation with the seasonal variation of biomass burning in Africa and South America. Northern hemisphere summer shows the widespread ozone and CO pollution throughout the middle latitudes. The inter-hemispheric gradient of ozone and CO found to be decreased during October. Large-scale transport of the ozone and CO over the Atlantic and Pacific Oceans has been clearly identified. Strong intercontinental transport has been observed to occur from west to east along with the mid-latitude winds in the northern hemisphere.
Imran Asatar, G., and P. R. Nair (2010), Spatial distribution of near-surface CO over bay of Bengal during winter: role of transport, Journal of Atmospheric and Solar-Terrestrial Physics, 72(17), 1241–1250, doi:10.1016/j.jastp.2010.07.025.
As part of Integrated Campaign for Aerosols, gases and Radiation Budget (ICARB), cruise-based measurements of near-surface CO were carried out over Bay of Bengal (BoB) covering the latitude–longitude sector 3.5°N–21.0°N and 76.0°E–98.0°E, during winter months of December 2008 to January 2009. These in-situ measured CO mixing ratio varied in the range of 80–480 ppbv over this marine environment with the distinct spatial pattern. The highest mixing ratios were measured over southeast-BoB with mean value of 379±58 ppbv. CO mixing ratios were high over north-BoB compared to southern BoB. These in-situ measurements were compared with the satellite-measured surface CO obtained from Measurements of Pollution in the Troposphere (MOPITT) onboard TERRA and found to be in good agreement over most of the regions, except at southeast-BoB. Surface CO and column CO from MOPITT data showed a similar spatial pattern. Based on the analysis of airmass back-trajectories, satellite-based spatial map of CO distribution over Asian region and Potential Source Contribution Function analysis, different pathways of transport of CO were identified. Transport from northern landmass as well as from south-east Asia has a significant influence in the spatial variation of CO over BoB. Winter-time mixing ratio of CO was found to be higher compared to those measured during other campaigns conducted during February–March 1999, 2001 (pre-monsoon) and September–October, 2002 (post-monsoon).
Jacob, D. J., J. H. Crawford, H. Maring, A. D. Clarke, J. E. Dibb, L. K. Emmons, R. A. Ferrare, C. A. Hostetler, P. B. Russell, H. B. Singh, A. M. Thompson, G. E. Shaw, E. McCauley, J. R. Pederson, and J. A. Fisher (2010), The Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission: design, execution, and first results, Atmos. Chem. Phys., 10(11), 5191–5212, doi:10.5194/acp-10-5191-2010.
The NASA Arctic Research of the Composition of the Troposphere from Aircraft and Satellites (ARCTAS) mission was conducted in two 3-week deployments based in Alaska (April 2008) and western Canada (June–July 2008). Its goal was to better understand the factors driving current changes in Arctic atmospheric composition and climate, including (1) influx of mid-latitude pollution, (2) boreal forest fires, (3) aerosol radiative forcing, and (4) chemical processes. The June–July deployment was preceded by one week of flights over California (ARCTAS-CARB) focused on (1) improving state emission inventories for greenhouse gases and aerosols, (2) providing observations to test and improve models of ozone and aerosol pollution. ARCTAS involved three aircraft: a DC-8 with a detailed chemical payload, a P-3 with an extensive aerosol and radiometric payload, and a B-200 with aerosol remote sensing instrumentation. The aircraft data augmented satellite observations of Arctic atmospheric composition, in particular from the NASA A-Train. The spring phase (ARCTAS-A) revealed pervasive Asian pollution throughout the Arctic as well as significant European pollution below 2 km. Unusually large Siberian fires in April 2008 caused high concentrations of carbonaceous aerosols and also affected ozone. Satellite observations of BrO column hotspots were found not to be related to Arctic boundary layer events but instead to tropopause depressions, suggesting the presence of elevated inorganic bromine (5–10 pptv) in the lower stratosphere. Fresh fire plumes from Canada and California sampled during the summer phase (ARCTAS-B) indicated low NOx emission factors from the fires, rapid conversion of NOx to PAN, no significant secondary aerosol production, and no significant ozone enhancements except when mixed with urban pollution.
Kar, J., M. N. Deeter, J. Fishman, Z. Liu, A. Omar, J. K. Creilson, C. R. Trepte, M. A. Vaughan, and D. M. Winker (2010), Wintertime pollution over the Eastern Indo-Gangetic Plains as observed from MOPITT, CALIPSO and tropospheric ozone residual data, Atmos. Chem. Phys., 10(24), 12273–12283, doi:10.5194/acp-10-12273-2010.
A large wintertime increase in pollutants has been observed over the eastern parts of the Indo Gangetic Plains. We use improved version 4 carbon monoxide (CO) retrievals from the Measurements of Pollution in the Troposphere (MOPITT) along with latest version 3 aerosol data from the Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observations (CALIPSO) lidar instrument and the tropospheric ozone residual products to characterize this pollution pool. The feature is seen primarily in the lower troposphere from about November to February with strong concomitant increases in CO and aerosol optical depth (AOD). The signature of the feature is also observed in tropospheric ozone column data. The height resolved aerosol data from CALIPSO confirm the trapping of the pollution pool at the lowest altitudes. The observations indicate that MOPITT can capture this low altitude phenomenon even in winter conditions as indicated by the averaging kernels.
Kopacz, M., D. J. Jacob, J. A. Fisher, J. A. Logan, L. Zhang, I. A. Megretskaia, R. M. Yantosca, K. Singh, D. K. Henze, J. P. Burrows, M. Buchwitz, I. Khlystova, W. W. McMillan, J. C. Gille, D. P. Edwards, A. Eldering, V. Thouret, and P. Nedelec (2010), Global estimates of CO sources with high resolution by adjoint inversion of multiple satellite datasets (MOPITT, AIRS, SCIAMACHY, TES), Atmos. Chem. Phys., 10(3), 855–876, doi:10.5194/acp-10-855-2010.
We combine CO column measurements from the MOPITT, AIRS, SCIAMACHY, and TES satellite instruments in a full-year (May 2004-April 2005) global inversion of CO sources at 4°×5° spatial resolution and monthly temporal resolution. The inversion uses the GEOS-Chem chemical transport model (CTM) and its adjoint applied to MOPITT, AIRS, and SCIAMACHY. Observations from TES, surface sites (NOAA/GMD), and aircraft (MOZAIC) are used for evaluation of the a posteriori solution. Using GEOS-Chem as a common intercomparison platform shows global consistency between the different satellite datasets and with the in situ data. Differences can be largely explained by different averaging kernels and a priori information. The global CO emission from combustion as constrained in the inversion is 1350 Tg a-1. This is much higher than current bottom-up emission inventories. A large fraction of the correction results from a seasonal underestimate of CO sources at northern mid-latitudes in winter and suggests a larger-than-expected CO source from vehicle cold starts and residential heating. Implementing this seasonal variation of emissions solves the long-standing problem of models underestimating CO in the northern extratropics in winter-spring. A posteriori emissions also indicate a general underestimation of biomass burning in the GFED2 inventory. However, the tropical biomass burning constraints are not quantitatively consistent across the different datasets.
de Laat, A. T. J., A. M. S. Gloudemans, I. Aben, and H. Schrijver (2010a), Global evaluation of SCIAMACHY and MOPITT carbon monoxide column differences for 2004–2005, Journal of Geophysical Research: Atmospheres, 115(D6), n/a–n/a, doi:10.1029/2009JD012698.
This paper presents a detailed global comparison of Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) and Measurement of Pollution in the Troposphere (MOPITT) carbon monoxide (CO) column measurements for the years 2004 and 2005. Qualitatively, spatiotemporal variations of SCIAMACHY and MOPITT are similar. Quantitative comparisons have been performed taking the effects of instrument noise errors, vertical sensitivities via the averaging kernel and a priori, different spatiotemporal sampling and clouds into account using simulated CO profiles from the TM4 model. SCIAMACHY and MOPITT CO columns are similar over tropical, subtropical, and Northern Hemisphere oceans as well as over boreal regions where SCIAMACHY and MOPITT agree to within 10% or 2 × 1017 molecules/cm2. The short-wave infrared SCIAMACHY observations also provide information about lower tropospheric CO in Arctic and subarctic regions north of 60°N, where the MOPITT sensitivity is strongly reduced. South of 45°S, SCIAMACHY CO columns are 3–5 × 1017 molecules/cm2 smaller than MOPITT CO columns. Approximately 1.5 × 1017 molecules/cm2 (∼10%) of this difference is attributed to a bias in the SCIAMACHY CO columns, which is currently under investigation. The remaining difference is possibly related to MOPITT biases in this region. In the transition from oceans to dry desert regions, MOPITT CO total columns show a rapid increase of approximately 3 × 1017 molecules/cm2 (∼15%). While MOPITT and SCIAMACHY agree over oceans, MOPITT is approximately 5 × 1017 molecules/cm2 (∼25%) larger than SCIAMACHY results over dry land regions. The origin of this bias needs further investigation.
de Laat, A. T. J., A. M. S. Gloudemans, H. Schrijver, I. Aben, Y. Nagahama, K. Suzuki, E. Mahieu, N. B. Jones, C. Paton-Walsh, N. M. Deutscher, D. W. T. Griffith, M. De Mazière, R. L. Mittermeier, H. Fast, J. Notholt, M. Palm, T. Hawat, T. Blumenstock, F. Hase, M. Schneider, C. Rinsland, A. V. Dzhola, E. I. Grechko, A. M. Poberovskii, M. V. Makarova, J. Mellqvist, A. Strandberg, R. Sussmann, T. Borsdorff, and M. Rettinger (2010b), Validation of five years (2003-2007) of SCIAMACHY CO total column measurements using ground-based spectrometer observations, Atmospheric Measurement Techniques, 3(5), 1457–1471, doi:10.5194/amt-3-1457-2010.
This paper presents a validation study of SCanning Imaging Absorption spectroMeter for Atmospheric CHartographY (SCIAMACHY) carbon monoxide (CO) total column measurements from the Iterative Maximum Likelihood Method (IMLM) algorithm using ground-based spectrometer observations from twenty surface stations for the five year time period of 2003-2007. Overall we find a good agreement between SCIAMACHY and ground-based observations for both mean values as well as seasonal variations. For high-latitude Northern Hemisphere stations absolute differences between SCIAMACHY and ground-based measurements are close to or fall within the SCIAMACHY CO 2 sigma precision of 0.2 x 10(18) molecules/cm(2) (similar to 10%) indicating that SCIAMACHY can observe CO accurately at high Northern Hemisphere latitudes. For Northern Hemisphere mid-latitude stations the validation is complicated due to the vicinity of emission sources for almost all stations, leading to higher ground-based measurements compared to SCIAMACHY CO within its typical sampling area of 8 degrees x 8 degrees. Comparisons with Northern Hemisphere mountain stations are hampered by elevation effects. After accounting for these effects, the validation provides satisfactory results. At Southern Hemisphere mid-to high latitudes SCIAMACHY is systematically lower than the ground-based measurements for 2003 and 2004, but for 2005 and later years the differences between SCIAMACHY and ground-based measurements fall within the SCIAMACHY precision. The 2003-2004 bias is consistent with previously reported results although its origin remains under investigation. No other systematic spatial or temporal biases could be identified based on the validation presented in this paper. Validation results are robust with regard to the choices of the instrument-noise error filter, sampling area, and time averaging required for the validation of SCIAMACHY CO total column measurements. Finally, our results show that the spatial coverage of the ground-based measurements available for the validation of the 2003-2007 SCIAMACHY CO columns is sub-optimal for validation purposes, and that the recent and ongoing expansion of the ground-based network by carefully selecting new locations may be very beneficial for SCIAMACHY CO and other satellite trace gas measurements validation efforts.
Lin, Y. C., C. Y. Lin, and W. T. Hsu (2010), Observations of carbon monoxide mixing ratios at a mountain site in central Taiwan during the Asian biomass burning season, Atmospheric Research, 95(2–3), 270–278, doi:10.1016/j.atmosres.2009.10.006.
Carbon monoxide (CO) mixing ratios were observed from 30 January to 7 April 2008 at Mt. Lulin (23.51°N, 120.92°E, 2862 m asl) in central Taiwan to investigate characteristics of CO during biomass burning periods. During the sampling campaign, the average mixing ratio of CO was 234 ± 63 ppb with higher levels observed in March. The elevated CO in March can, on the basis of backward trajectories and satellite fire spots analyses, possibly be attributed to biomass burning activities in the Asian continent. Significant diurnal variations of CO mixing ratios were observed at the remote site. The higher CO levels in the afternoon were influenced by the transport of boundary layer pollution to the site during daytime upslope flow. Backward trajectory analysis showed that air masses mainly originated from India (ID), the Indochina Peninsula (IP) and South Coastal China (SC), which together accounted for 85% of the total trajectories. Higher mixing ratios of CO were found in the ID, IP, and SC categories, indicating significant impacts of anthropogenic emissions on the Pacific region. Furthermore, the air parcels were divided into two categories, those that passed over the fire regions and those that did not. The result showed that the average difference of CO levels between the two categories was approximately 79 ppb, suggesting that Asian biomass burning plays an important role in CO levels at this remote site during the springtime.
Longo, K. M., S. R. Freitas, M. O. Andreae, A. Setzer, E. Prins, and P. Artaxo (2010), The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 2: Model sensitivity to the biomass burning inventories, Atmos. Chem. Phys., 10(13), 5785–5795, doi:10.5194/acp-10-5785-2010.
We describe an estimation technique for biomass burning emissions in South America based on a combination of remote-sensing fire products and field observations, the Brazilian Biomass Burning Emission Model (3BEM). For each fire pixel detected by remote sensing, the mass of the emitted tracer is calculated based on field observations of fire properties related to the type of vegetation burning. The burnt area is estimated from the instantaneous fire size retrieved by remote sensing, when available, or from statistical properties of the burn scars. The sources are then spatially and temporally distributed and assimilated daily by the Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) in order to perform the prognosis of related tracer concentrations. Three other biomass burning inventories, including GFEDv2 and EDGAR, are simultaneously used to compare the emission strength in terms of the resultant tracer distribution. We also assess the effect of using the daily time resolution of fire emissions by including runs with monthly-averaged emissions. We evaluate the performance of the model using the different emission estimation techniques by comparing the model results with direct measurements of carbon monoxide both near-surface and airborne, as well as remote sensing derived products. The model results obtained using the 3BEM methodology of estimation introduced in this paper show relatively good agreement with the direct measurements and MOPITT data product, suggesting the reliability of the model at local to regional scales.
Luo, M., C. Boxe, J. Jiang, R. Nassar, and N. Livesey (2010), Interpretation of Aura satellite observations of CO and aerosol index related to the December 2006 Australia fires, Remote Sensing of Environment, 114(12), 2853–2862, doi:10.1016/j.rse.2010.07.003.
Enhanced carbon monoxide (CO) in the upper troposphere (UT) is shown by nearly collocated Tropospheric Emission Spectrometer (TES) and Microwave Limb Sounder (MLS) measurements near and down-wind from the known wildfire region of SE Australia from December 12th–19th, 2006. Enhanced ultraviolet (UV) aerosol index (AI) derived from the Ozone Monitoring Instrument (OMI) measurements correlates with these high CO concentrations. The Hybrid Single Particle Langrangian Integrated Trajectory (HYSPLIT) model back trajectories trace selected air parcels, where TES observes enhanced CO in the upper and lower troposphere, to the SE Australia fire region as their initial location. Simultaneously, they show a lack of vertical advection along their tracks. TES retrieved CO vertical profiles in the higher and lower southern latitudes are examined together with the averaging kernels and show that TES CO retrievals are most sensitive at approximately 300–400 hPa. The enhanced CO observed by TES in the upper (215 hPa) and lower (681 hPa) troposphere are, therefore, influenced by mid-tropospheric CO. GEOS-Chem model simulations with an 8-day emission inventory, as the wildfire source over Australia, are sampled to the TES/MLS observation times and locations. These simulations only show CO enhancements in the lower troposphere near and down-wind from the wildfire region of SE Australia with drastic underestimates of UT CO plumes. Although CloudSat along-track ice-water content curtains are examined to see whether possible vertical convection events can explain the high UT CO values, sparse observations of collocated Aura CO and CloudSat along-track ice-water content measurements for the single event precludes any conclusive correlation. Vertical convection that uplifts the fire-induced CO (i.e., most notably referred to as pyro-cumulonimbus (pyroCb)) may provide an explanation for the incongruence between these simulations and the TES/MLS observations of enhanced CO in the UT.
Mieville, A., C. Granier, C. Liousse, B. Guillaume, F. Mouillot, J.-F. Lamarque, J.-M. Grégoire, and G. Pétron (2010), Emissions of gases and particles from biomass burning during the 20th century using satellite data and an historical reconstruction, Atmospheric Environment, 44(11), 1469–1477, doi:10.1016/j.atmosenv.2010.01.011.
A new dataset of emissions of trace gases and particles resulting from biomass burning has been developed for the historical and the recent period (1900–2005). The purpose of this work is to provide a consistent gridded emissions dataset of atmospheric chemical species from 1900 to 2005 for chemistry-climate simulations. The inventory is built in two steps. First, fire emissions are estimated for the recent period (1997–2005) using satellite products (GBA2000 burnt areas and ATSR fire hotspots); the temporal and spatial distribution of the CO2 emissions for the 1997–2005 period is estimated through a calibration of ATSR fire hotspots. The historical inventory, covering the 1900–2000 period on a decadal basis, is derived from the historical reconstruction of burned areas from Mouillot and Field (2005). The historical emissions estimates are forced, for each main ecosystem, to agree with the recent inventory estimates, ensuring consistency between past and recent emissions. The methodology used for estimating the fire emissions is discussed, together with the time evolution of biomass burning emissions during the 20th century, first at the global scale and then for specific regions. The results are compared with the distributions provided by other inventories and results of inverse modeling studies.
Nam, J., Y. Wang, C. Luo, and D. A. Chu (2010), Trans-Pacific transport of Asian dust and CO: accumulation of biomass burning CO in the subtropics and dipole structure of transport, Atmos. Chem. Phys., 10(7), 3297–3308, doi:10.5194/acp-10-3297-2010.
In May 2003, both MODIS aerosol optical depth (AOD) and carbon monoxide (CO) measurements from MOPITT show significant trans-Pacific transport to North America. We apply the global chemical transport model, GEOS-Chem, to analyze the main features of the long-range transport events. Enhancements of MOPITT CO over the tropical Pacific are much broader than MODIS AOD enhancements. We find in model simulations that a major fraction of the CO enhancements in the subtropics in May is due to biomass burning in Southeast Asia in April. Biomass burning CO was recirculated into the subtropical high-pressure system and lingered for a much longer period than aerosols transported at higher latitudes. Simulated AOD enhancements are due to a combination of dust, sulfate, and organic and elemental carbons. Dust contribution dominates the AOD enhancements in early May. Model results indicate that dust transport takes place at higher altitude than the other aerosols. MODIS observations indicate a bias in model simulated pathway of dust transport in one out of the three cases analyzed. Sensitivities of dust transport pathways are analyzed in the model. The dipole structure of transport, consisting of the Aleutian Low to the north and the Pacific High to the south, over the Pacific is found to be a key factor. The placement of the dipole structure relative to model parameters such as up-stream wind field and source location may lead to the high sensitivity of simulated transport pathways.
Ordóñez, C., N. Elguindi, O. Stein, V. Huijnen, J. Flemming, A. Inness, H. Flentje, E. Katragkou, P. Moinat, V.-H. Peuch, A. Segers, V. Thouret, G. Athier, M. van Weele, C. S. Zerefos, J.-P. Cammas, and M. G. Schultz (2010), Global model simulations of air pollution during the 2003 European heat wave, Atmos. Chem. Phys., 10(2), 789–815, doi:10.5194/acp-10-789-2010.
Three global Chemistry Transport Models - MOZART, MOCAGE, and TM5 - as well as MOZART coupled to the IFS meteorological model including assimilation of ozone (O3) and carbon monoxide (CO) satellite column retrievals, have been compared to surface measurements and MOZAIC vertical profiles in the troposphere over Western/Central Europe for summer 2003. The models reproduce the meteorological features and enhancement of pollution during the period 2-14 August, but not fully the ozone and CO mixing ratios measured during that episode. Modified normalised mean biases are around -25% (except ∼5% for MOCAGE) in the case of ozone and from -80% to -30% for CO in the boundary layer above Frankfurt. The coupling and assimilation of CO columns from MOPITT overcomes some of the deficiencies in the treatment of transport, chemistry and emissions in MOZART, reducing the negative biases to around 20%. The high reactivity and small dry deposition velocities in MOCAGE seem to be responsible for the overestimation of O3 in this model. Results from sensitivity simulations indicate that an increase of the horizontal resolution to around 1°×1° and potential uncertainties in European anthropogenic emissions or in long-range transport of pollution cannot completely account for the underestimation of CO and O3 found for most models. A process-oriented TM5 sensitivity simulation where soil wetness was reduced results in a decrease in dry deposition fluxes and a subsequent ozone increase larger than the ozone changes due to the previous sensitivity runs. However this latest simulation still underestimates ozone during the heat wave and overestimates it outside that period. Most probably, a combination of the mentioned factors together with underrepresented biogenic emissions in the models, uncertainties in the modelling of vertical/horizontal transport processes in the proximity of the boundary layer as well as limitations of the chemistry schemes are responsible for the underestimation of ozone (overestimation in the case of MOCAGE) and CO found in the models during this extreme pollution event.
Pfister, G. G., L. K. Emmons, D. P. Edwards, A. Arellano, G Sachse, and T. Campos (2010), Variability of springtime transpacific pollution transport during 2000–2006: the INTEX-B mission in the context of previous years, Atmos. Chem. Phys., 10(3), 1345–1359, doi:10.5194/acp-10-1345-2010.
We analyze the transport of pollution across the Pacific during the NASA INTEX-B (Intercontinental Chemical Transport Experiment Part B) campaign in spring 2006 and examine how this year compares to the time period for 2000 through 2006. In addition to aircraft measurements of carbon monoxide (CO) collected during INTEX-B, we include in this study multi-year satellite retrievals of CO from the Measurements of Pollution in the Troposphere (MOPITT) instrument and simulations from the chemistry transport model MOZART-4. Model tracers are used to examine the contributions of different source regions and source types to pollution levels over the Pacific. Additional modeling studies are performed to separate the impacts of inter-annual variability in meteorology and dynamics from changes in source strength. Interannual variability in the tropospheric CO burden over the Pacific and the US as estimated from the MOPITT data range up to 7% and a somewhat smaller estimate (5%) is derived from the model. When keeping the emissions in the model constant between years, the year-to-year changes are reduced (2%), but show that in addition to changes in emissions, variable meteorological conditions also impact transpacific pollution transport. We estimate that about 1/3 of the variability in the tropospheric CO loading over the contiguous US is explained by changes in emissions and about 2/3 by changes in meteorology and transport. Biomass burning sources are found to be a larger driver for inter-annual variability in the CO loading compared to fossil and biofuel sources or photochemical CO production even though their absolute contributions are smaller. Source contribution analysis shows that the aircraft sampling during INTEX-B was fairly representative of the larger scale region, but with a slight bias towards higher influence from Asian contributions.
Reeves, C. E., P. Formenti, C. Afif, G. Ancellet, J.-L. Attié, J. Bechara, A. Borbon, F. Cairo, H. Coe, S. Crumeyrolle, F. Fierli, C. Flamant, L. Gomes, T. Hamburger, C. Jambert, K. S. Law, C. Mari, R. L. Jones, A. Matsuki, M. I. Mead, J. Methven, G. P. Mills, A. Minikin, J. G. Murphy, J. K. Nielsen, D. E. Oram, D. J. Parker, A. Richter, H. Schlager, A. Schwarzenboeck, and V. Thouret (2010), Chemical and aerosol characterisation of the troposphere over West Africa during the monsoon period as part of AMMA, Atmos. Chem. Phys., 10(16), 7575–7601, doi:10.5194/acp-10-7575-2010.
During June, July and August 2006 five aircraft took part in a campaign over West Africa to observe the aerosol content and chemical composition of the troposphere and lower stratosphere as part of the African Monsoon Multidisciplinary Analysis (AMMA) project. These are the first such measurements in this region during the monsoon period. In addition to providing an overview of the tropospheric composition, this paper provides a description of the measurement strategy (flights performed, instrumental payloads, wing-tip to wing-tip comparisons) and points to some of the important findings discussed in more detail in other papers in this special issue.  The ozone data exhibits an “S” shaped vertical profile which appears to result from significant losses in the lower troposphere due to rapid deposition to forested areas and photochemical destruction in the moist monsoon air, and convective uplift of ozone-poor air to the upper troposphere. This profile is disturbed, particularly in the south of the region, by the intrusions in the lower and middle troposphere of air from the southern hemisphere impacted by biomass burning. Comparisons with longer term data sets suggest the impact of these intrusions on West Africa in 2006 was greater than in other recent wet seasons. There is evidence for net photochemical production of ozone in these biomass burning plumes as well as in urban plumes, in particular that from Lagos, convective outflow in the upper troposphere and in boundary layer air affected by nitrogen oxide emissions from recently wetted soils. This latter effect, along with enhanced deposition to the forested areas, contributes to a latitudinal gradient of ozone in the lower troposphere. Biogenic volatile organic compounds are also important in defining the composition both for the boundary layer and upper tropospheric convective outflow.  Mineral dust was found to be the most abundant and ubiquitous aerosol type in the atmosphere over Western Africa. Data collected within AMMA indicate that injection of dust to altitudes favourable for long-range transport (i.e. in the upper Sahelian planetary boundary layer) can occur behind the leading edge of mesoscale convective system (MCS) cold-pools. Research within AMMA also provides the first estimates of secondary organic aerosols across the West African Sahel and have shown that organic mass loadings vary between 0 and 2 μg m−3 with a median concentration of 1.07 μg m−3. The vertical distribution of nucleation mode particle concentrations reveals that significant and fairly strong particle formation events did occur for a considerable fraction of measurement time above 8 km (and only there). Very low concentrations were observed in general in the fresh outflow of active MCSs, likely as the result of efficient wet removal of aerosol particles due to heavy precipitation inside the convective cells of the MCSs. This wet removal initially affects all particle size ranges as clearly shown by all measurements in the vicinity of MCSs.
Singh, R. P., J. Senthil Kumar, J. Zlotnicki, and M. Kafatos (2010), Satellite detection of carbon monoxide emission prior to the Gujarat earthquake of 26 January 2001, Applied Geochemistry, 25(4), 580–585, doi:10.1016/j.apgeochem.2010.01.014.
NOAA AVHRR images have clearly shown anomalous changes in land surface temperature associated with earthquakes in the past two decades. Soon after the Gujarat earthquake of January 26, 2001, an anomalous increase in land surface temperature was inferred from MODIS satellite data a few days prior to the main earthquake event. The cause of such an anomalous change in surface temperature prior to the earthquake is attributed to many probable phenomena, but no definite cause has been identified. In the present study, changes of a complementary nature were found of land surface temperature associated with the emission of CO from the epicentral region. The observed changes on land and atmosphere associated with the Gujarat earthquake of 26 January, 2001, show the existence of strong coupling between land, atmosphere and ionosphere.
Srivastava, S., S. Lal, D. B. Subrahamanyam, S. Gupta, S. Venkataramani, and T. A. Rajesh (2010), Seasonal variability in mixed layer height and its impact on trace gas distribution over a tropical urban site: Ahmedabad, Atmospheric Research, 96(1), 79–87, doi:10.1016/j.atmosres.2009.11.015.
Altitude profiles of virtual potential temperature (θv) and specific humidity (q) derived from meteorological data obtained from balloon-borne radiosonde ascents are used to investigate the seasonal variations in mixed layer height over Ahmedabad (23.03°N, 72.54°E), an urban site located on the western part of India. A total of 82 balloon ascents were conducted fortnightly in the morning hours during a period of about four years spanning from April 2003 to July 2007. Analysis of the vertical profiles of θv and q reveals a systematic seasonal variability in the mixed layer height (MLH), showing the decreasing trend from summer–monsoon to winter season. The MLH is observed to be maximum (∼ 1170 m) in summer–monsoon while a minimum (∼ 160 m) is observed during the winter months. In general, the mixed layer height was found to be highly variant during pre-monsoon and summer–monsoon seasons. This variability is observed to be comparatively lower in the post-monsoon and winter months. Effects of MLH have been investigated on the variations in surface ozone and MOPITT derived surface and vertical distributions of CO. The reverse trend is observed in surface ozone and CO with mixed layer seasonal variability. The impact of MLH over CO vertical distributions is observed up to an altitude of 3–4 km.
Stroppiana, D., P. A. Brivio, J.-M. Grégoire, C. Liousse, B. Guillaume, C. Granier, A. Mieville, M. Chin, and G. Pétron (2010), Comparison of global inventories of CO emissions from biomass burning derived from remotely sensed data, Atmos. Chem. Phys., 10(24), 12173–12189, doi:10.5194/acp-10-12173-2010.
We compare five global inventories of monthly CO emissions named VGT, ATSR, MODIS, GFED3 and MOPITT based on remotely sensed active fires and/or burned area products for the year 2003. The objective is to highlight similarities and differences by focusing on the geographical and temporal distribution and on the emissions for three broad land cover classes (forest, savanna/grassland and agriculture). Globally, CO emissions for the year 2003 range between 365 Tg CO (GFED3) and 1422 Tg CO (VGT). Despite the large uncertainty in the total amounts, some common spatial patterns typical of biomass burning can be identified in the boreal forests of Siberia, in agricultural areas of Eastern Europe and Russia and in savanna ecosystems of South America, Africa and Australia. Regionally, the largest difference in terms of total amounts (CV > 100%) and seasonality is observed at the northernmost latitudes, especially in North America and Siberia where VGT appears to overestimate the area affected by fires. On the contrary, Africa shows the best agreement both in terms of total annual amounts (CV = 31%) and of seasonality despite some overestimation of emissions from forest and agriculture observed in the MODIS inventory. In Africa VGT provides the most reliable seasonality. Looking at the broad land cover types, the range of contribution to the global emissions of CO is 64-74%, 23-32% and 3-4% for forest, savanna/grassland and agriculture, respectively. These results suggest that there is still large uncertainty in global estimates of emissions and it increases if the comparison is carried by out taking into account the temporal (month) and spatial (0.5° × 0.5° cell) dimensions. Besides the area affected by fires, also vegetation characteristics and conditions at the time of burning should also be accurately parameterized since they can greatly influence the global estimates of CO emissions.
Warner, J. X., Z. Wei, L. L. Strow, C. D. Barnet, L. C. Sparling, G. Diskin, and G. Sachse (2010), Improved agreement of AIRS tropospheric carbon monoxide products with other EOS sensors using optimal estimation retrievals, Atmos. Chem. Phys., 10(19), 9521–9533, doi:10.5194/acp-10-9521-2010.
We present in this paper an alternative retrieval algorithm for the Atmospheric Infrared Sounder (AIRS) tropospheric Carbon Monoxide (CO) products using the Optimal Estimation (OE) technique, which is different from the AIRS operational algorithm. The primary objective for this study was to compare AIRS CO, as well as the other retrieval properties such as the Averaging Kernels (AKs), the Degrees of Freedom for Signal (DOFS), and the error covariance matrix, against the Tropospheric Emission Spectrometer (TES) and the Measurement of Pollution in the Troposphere (MOPITT) CO, which were also derived using the OE technique. We also demonstrate that AIRS OE CO results are much more realistic than AIRS V5 operational CO, especially in the lower troposphere and in the Southern Hemisphere (SH). These products are validated with in situ profiles obtained by the Differential Absorption Carbon Monoxide Measurements (DACOM), which took place as part of NASA’s Intercontinental Chemical Transport Experiment (INTEX-B) field mission that was conducted over the northern Pacific in Spring 2006. To demonstrate the differences existing in the current operational products we first show a detailed direct comparison between AIRS V5 and TES operational V3 CO for the global datasets from December 2005 to July 2008. We then present global CO comparisons between AIRS OE, TES V3, and MOPITT V4 at selected pressure levels as well as for the total column amounts. We conclude that the tropospheric CO retrievals from AIRS OE and TES V3 agree to within 5–10 ppbv or 5% on average globally and throughout the free troposphere. The agreements in total column CO amounts between AIRS OE and MOPITT V4 have improved significantly compared to AIRS V5 with global relative RMS differences now being 12.7%.
Worden, H. M., M. N. Deeter, D. P. Edwards, J. C. Gille, J. R. Drummond, and P. Nédélec (2010), Observations of near-surface carbon monoxide from space using MOPITT multispectral retrievals, Journal of Geophysical Research (Atmospheres), 115(d14), 18314, doi:10.1029/2010JD014242.
Using both thermal infrared (TIR) and near infrared (NIR) channels of MOPITT (Measurements of Pollution in the Troposphere) on EOS-Terra, we demonstrate the first coincident multispectral retrievals of carbon monoxide (CO) from space. Exploiting both TIR and NIR channels has been possible due to recent progress in characterizing NIR channel radiance errors. This has allowed us to trade off sensitivity to near surface CO for larger random errors in the combined retrieval. By examining retrieval diagnostics such as DFS (degrees of freedom for signal) and averaging kernels for the multispectral retrieval (TIR + NIR) as compared to the TIR-only retrieval, we find that adding the NIR channel to the retrieval significantly increases sensitivity to CO, especially near the surface, but with high spatial variability due to surface albedo variations. The cases with the largest increases in DFS are over regions with low thermal contrast between the surface and lower atmosphere. In the tropics (23.4°S-23.4°N), the fraction of daytime land cases with at least 0.4 DFS in the surface layer (surface to 800 hPa) is 20% for TIR-only retrievals compared to 59% for multispectral retrievals. Vertical resolution for the surface layer is also improved, in some cases from around 6 km for TIR-only to roughly 1 km for TIR + NIR. Since we apply a single a priori CO profile (unlike MOPITT V4) and error covariance in all the retrievals reported here, these increases are due solely to the addition of the NIR channel. Enhanced sensitivity to near surface CO is especially evident in a case study for central/east Asia where source regions for urban areas with high population density are clearly identifiable. Although these retrievals are still a research product and require further validation and scientific evaluation, they demonstrate the increased sensitivity to CO in the lowermost troposphere that can be obtained from multispectral MOPITT data.
Yurganov, L., W. McMillan, E. Grechko, and A. Dzhola (2010), Analysis of global and regional CO burdens measured from space between 2000 and 2009 and validated by ground-based solar tracking spectrometers, Atmos. Chem. Phys., 10(8), 3479–3494, doi:10.5194/acp-10-3479-2010.
Interannual variations in AIRS and MOPITT retrieved CO burdens are validated, corrected, and compared with CO emissions from wild fires from the Global Fire Emission Dataset (GFED2) inventory. Validation of daily mean CO total column (TC) retrievals from MOPITT version 3 and AIRS version 5 is performed through comparisons with archived TC data from the Network for Detection of Atmospheric Composition Change (NDACC) ground-based Fourier Transform Spectrometers (FTS) between March 2000 and December 2007. MOPITT V3 retrievals exhibit an increasing temporal bias with a rate of 1.4-1.8% per year; thus far, AIRS retrievals appear to be more stable. For the lowest CO values in the Southern Hemisphere (SH), AIRS TC retrievals overestimate FTS TC by 20%. MOPITT’s bias and standard deviation do not depend on CO TC absolute values. Empirical corrections are derived for AIRS and MOPITT retrievals based on the observed annually averaged bias versus the FTS TC. Recently published MOPITT V4 is found to be in a good agreement with MOPITT V3 corrected by us (with exception of 2000-2001 period). With these corrections, CO burdens from AIRS V5 and MOPITT V3 (as well as MOPITT V4) come into good agreement in the mid-latitudes of the Northern Hemisphere (NH) and in the tropical belt. In the SH, agreement between AIRS and MOPITT CO burdens is better for the larger CO TC in austral winter and worse in austral summer when CO TC are smaller. Before July 2008, all variations in retrieved CO burden can be explained by changes in fire emissions. After July 2008, global and tropical CO burdens decreased until October before recovering by the beginning of 2009. The NH CO burden also decreased but reached a minimum in January 2009 before starting to recover. The decrease in tropical CO burdens is explained by lower than usual fire emissions in South America and Indonesia. This decrease in tropical emissions also accounts for most of the change in the global CO burden. However, no such diminution of NH biomass burning is indicated by GFED2. Thus, the CO burden decrease in the NH could result from a combination of lower fossil fuel emissions during the global economic recession and transport of CO-poor air from the tropics. More extensive modeling will be required to fully resolve this issue.
Zhang, Y., S. C. Olsen, and M. K. Dubey (2010), WRF/Chem simulated springtime impact of rising Asian emissions on air quality over the U.S., Atmospheric Environment, 44(24), 2799–2812, doi:10.1016/j.atmosenv.2010.05.003.
This paper examines the impact of tripled anthropogenic emissions from China and India over the base level (gaseous species and carbonaceous aerosols for 2000) on air quality over the U.S. using the WRF/Chem (Weather Research and Forecasting – Chemistry) model at 1° resolution. WRF/Chem is a state-of-the-science, fully coupled chemistry and meteorology system suitable for simulating the transport and dispersion of pollutants and their impacts. The analyses in this work were focused on MAM (March, April and May). The simulations indicate an extensive area of elevated pollutant concentrations spanning from the Arabian Sea to the Northern Pacific and to the Northern Atlantic. MAM mean contributions from the tripled Asian emissions over the U.S. are found to be: 6–12 ppbv for CO, 1.0–2.5 ppbv for O3, and 0.6–1.6 μg m−3 for PM2.5 on a daily basis.

2009

Badarinath, K. V. S., S. K. Kharol, A. R. Sharma, and V. Krishna Prasad (2009), Analysis of aerosol and carbon monoxide characteristics over Arabian Sea during crop residue burning period in the Indo-Gangetic Plains using multi-satellite remote sensing datasets, Journal of Atmospheric and Solar-Terrestrial Physics, 71(12), 1267–1276, doi:10.1016/j.jastp.2009.04.004.
In this study, we have used multi-satellite data to retrieve aerosol loadings and carbon monoxide (CO) pollution over the Arabian Sea, caused due to anthropogenic activities over the Indo-Gangetic Plains (IGP) in India. Relatively high aerosol and CO loadings during 9–14 November 2007 over Arabian Sea were attributed to crop residues burning in the IGP and fireworks during Diwali festival. Aerosol index (AI) obtained from ozone monitoring instrument (OMI) and CO from measurements of pollution in the troposphere instrument (MOPITT). CO showed higher values over the Arabian Sea suggesting long-range transport of anthropogenic aerosols and trace gases from the continental to Arabian Sea region.
Bowman, K. W., D. B. A. Jones, J. A. Logan, H. Worden, F. Boersma, R. Chang, S. Kulawik, G. Osterman, P. Hamer, and J. Worden (2009), The zonal structure of tropical O3 and CO as observed by the Tropospheric Emission Spectrometer in November 2004 – Part 2: Impact of surface emissions  on O3 and its precursors, Atmos. Chem. Phys., 9(11), 3563–3582, doi:10.5194/acp-9-3563-2009.
The impact of surface emissions on the zonal structure of tropical tropospheric ozone and carbon monoxide is investigated for November 2004 using satellite observations, in-situ measurements, and chemical transport models in conjunction with inverse-estimated surface emissions.Vertical ozone profiles from the Tropospheric Emission Spectrometer (TES) and ozone sonde measurements from the Southern Hemisphere Additional Ozonesondes (SHADOZ) network show elevated concentrations of ozone over Indonesia and Australia (60-70 ppb) in the lower troposphere against the backdrop of the well-known zonal ”wave-one” pattern with ozone concentrations of (70-80 ppb) centered over the Atlantic . Observational evidence from TES CO vertical profiles and Ozone Monitoring Instrument (OMI) NO2 columns point to regional surface emissions as an important contributor to the elevated ozone over Indonesia. This contribution is investigated with the GEOS-Chem chemistry and transport model using surface emission estimates derived from an optimal inverse model, which was constrained by TES and Measurements Of Pollution In The Troposphere (MOPITT) CO profiles (Jones et al., 2009). These a posteriori estimates, which were over a factor of 2 greater than climatological emissions, reduced differences between GEOS-Chem and TES ozone observations by 30-40% over Indonesia. The response of the free tropospheric chemical state to the changes in these emissions is investigated for ozone, CO, NOx, and PAN. Model simulations indicate that ozone over Indonesian/Australian is sensitive to regional changes in surface emissions of NOx but relatively insensitive to lightning NOx. Over sub-equatorial Africa and South America, free tropospheric NOx was reduced in response to increased surface emissions potentially muting ozone production.
Chen, D., Y. Wang, M. B. McElroy, K. He, R. M. Yantosca, and P. Le Sager (2009a), Regional CO pollution and export in China simulated by the high-resolution nested-grid GEOS-Chem model, Atmos. Chem. Phys., 9(11), 3825–3839, doi:10.5194/acp-9-3825-2009.
An updated version of the nested-grid GEOS-Chem model is developed allowing for higher horizontal (0.5 degree 0.667 degree ) resolution as compared to global models. CO transport over a heavily polluted region, the Beijing-Tianjin-Hebei (BTH) city cluster in China, and the pattern of outflow from East China in summertime are investigated. Comparison of the nested-grid with global models indicates that the fine-resolution nested-grid model is capable of resolving individual cities with high associated emission intensities. The nested-grid model indicates the presence of a high CO column density over the Sichuan Basin in summer, attributable to the low-level stationary vortex associated with the Basin’s topographical features. The nested-grid model provides good agreement also with measurements from a suburban monitoring site in Beijing during summer 2005. Tagged CO simulation results suggest that regional emissions make significant contributions to elevated CO levels over Beijing on polluted days and that the southeastward moving cyclones bringing northwest winds to Beijing are the key meteorological mechanisms responsible for dispersion of pollution over Beijing in summer. Overall CO fluxes to the NW Pacific from Asia are found to decrease by a factor of 3-4 from spring to summer. Much of the seasonal change is driven by decreasing fluxes from India and Southeast Asia in summer, while fluxes from East China are only 30% lower in summer than in spring. Compared to spring, summertime outflow from Chinese source regions is strongest at higher latitudes (north of 35 degree N). The deeper convection in summer transporting CO to higher altitudes where export is more efficient is largely responsible for enhanced export in summer.
Chen, Y., Q. Li, J. T. Randerson, E. A. Lyons, R. A. Kahn, D. L. Nelson, and D. J. Diner (2009b), The sensitivity of CO and aerosol transport to the temporal and vertical distribution of North American boreal fire emissions, Atmos. Chem. Phys., 9(17), 6559–6580, doi:10.5194/acp-9-6559-2009.
Forest fires in Alaska and western Canada represent important sources of aerosols and trace gases in North America. Among the largest uncertainties when modeling forest fire effects are the timing and injection height of biomass burning emissions. Here we simulate CO and aerosols over North America during the 2004 fire season, using the GEOS-Chem chemical transport model. We apply different temporal distributions and injection height profiles to the biomass burning emissions, and compare model results with satellite-, aircraft-, and ground-based measurements. We find that averaged over the fire season, the use of finer temporal resolved biomass burning emissions usually decreases CO and aerosol concentrations near the fire source region, and often enhances long-range transport. Among the individual temporal constraints, switching from monthly to 8-day time intervals for emissions has the largest effect on CO and aerosol distributions, and shows better agreement with measured day-to-day variability. Injection height substantially modifies the surface concentrations and vertical profiles of pollutants near the source region. Compared with CO, the simulation of black carbon aerosol is more sensitive to the temporal and injection height distribution of emissions. The use of MISR-derived injection heights improves agreement with surface aerosol measurements near the fire source. Our results indicate that the discrepancies between model simulations and MOPITT CO measurements near the Hudson Bay can not be attributed solely to the representation of injection height within the model. Frequent occurrence of strong convection in North America during summer tends to limit the influence of injection height parameterizations of fire emissions in Alaska and western Canada with respect to CO and aerosol distributions over eastern North America.
Chevallier, F., A. Fortems, P. Bousquet, I. Pison, S. Szopa, M. Devaux, and D. A. Hauglustaine (2009), African CO emissions between years 2000 and 2006 as estimated from MOPITT observations, Biogeosciences, 6(1), 103–111, doi:10.5194/bg-6-103-2009.
The space-time variations of the carbon budget at the Earth’s surface are highly variable and quantifying them represents a major scientific challenge. One strategy consists in inferring the carbon surface fluxes from the atmospheric concentrations. An inversion scheme for the hydrocarbon oxidation chain, that includes CO and CH(4), is presented here with a focus on the African continent. It is based on a variational principle. The multi-tracer system has been built as an extension of a system initially developed for CO(2) and includes a new simplified non-linear chemistry module. Individual in situ measurements of methyl-chloroform and individual retrievals of CO concentrations from the Measurements Of Pollution In The Troposphere (MOPITT) space-born instrument have been processed by the new system for the period 2000-2006 to infer the time series of CO emissions at the resolution of 2.5 degrees x 3.75 degrees (latitude, longitude). It is shown that the analysed concentrations improve the fit to five independent surface measurement stations located in or near Africa by up to 28% compared to standard inventories, which confirms that significant information about CO emissions can be obtained from MOPITT data. In practice, the inversion reduces the amplitude and the interannual variability of the seasonal cycle in the northern part of Africa, with a longer burning season. In the southern part, the inversion mainly shifts the emission peak by one month later in the season, consistent with previously-published inversion results.
Deeter, M. N., D. P. Edwards, J. C. Gille, and J. R. Drummond (2009), CO retrievals based on MOPITT near-infrared observations, Journal of Geophysical Research (Atmospheres), 114(d13), 4303, doi:10.1029/2008JD010872.
We report the first retrieval results of tropospheric carbon monoxide (CO) exclusively using near-infrared (NIR) radiances in the 2.3 μm CO overtone band observed by the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument. For daytime overpasses over land, such observations complement MOPITT’s thermal infrared (TIR) observations in the 4.7 μm CO fundamental band, especially for constraining the CO total column. Retrievals are performed in an optimal estimation framework in which effective radiance errors due to geophysical sources are estimated empirically. The new NIR-based retrievals are evaluated through comparisons with both the standard TIR-based MOPITT CO product and CO profile measurements.
Ding, A., T. Wang, L. Xue, J. Gao, A. Stohl, H. Lei, D. Jin, Y. Ren, X. Wang, X. Wei, Y. Qi, J. Liu, and X. Zhang (2009), Transport of north China air pollution by midlatitude cyclones: Case study of aircraft measurements in summer 2007, Journal of Geophysical Research: Atmospheres, 114(D8), n/a–n/a, doi:10.1029/2008JD011023.
Warm conveyor belts (WCBs) and frontal activity play important roles in the long-range transport of air pollutants by lifting them from the planetary boundary layer (PBL) into the free troposphere (FT) in midlatitudes. In summer 2007, an aircraft study was carried out in northeast (NE) China in order to understand the role of midlatitude cyclones in air pollution transport in north and east China in warm seasons. During a flight on 27 June, high concentrations of ozone and related trace gases were observed, with maximum concentrations (O3 ∼ 140 ppbv, SO2 ∼ 14.6 ppbv, CO ∼ 1185 ppbv) recorded at an altitude of 2.6 km. In this paper we present a detailed analysis of this flight. The mesoscale meteorological model Weather Research and Forecasting (WRF) and a Lagrangian dispersion model called FLEXPART were used to aid the diagnostic analysis of the atmospheric dynamic structure and the understanding of the transport characteristics of regional and local air pollution. The flight took place in a region adjacent to a warm front associated with a weak cyclone in north China. The aircraft sampled both the WCB and warm air frontal zone of the cyclone. The simulations show that the observed high air pollution in the FT mostly originated from the North China Plain, especially the megacities Beijing and Tianjin. Their plumes were vented by a stagnant front, probably through, in part, topographic lifting by the mountains in the north, and then were quickly transported in the FT to the study region. Trajectory analysis and satellite data suggest that the observed air masses were further lifted by the WCB into the middle and upper troposphere and were exported from Asia toward North America and the Arctic.
Edwards, D. P., A. F. Arellano, and M. N. Deeter (2009), A satellite observation system simulation experiment for carbon monoxide  in the lowermost troposphere, J. Geophys. Res.-Atmos., 114, doi:10.1029/2008JD011375.
We demonstrate the feasibility of using observing system simulation experiment (OSSE) studies to help define quantitative trace gas measurement requirements for satellite missions and to evaluate the expected performance of proposed observing strategies. The 2007 U. S. National Research Council Decadal Survey calls for a geostationary (GEO) satellite mission for atmospheric composition and air quality applications (Geostationary Coastal and Air Pollution Events Mission (GEO-CAPE)). The requirement includes a multispectral (near-infrared and thermal infrared) measurement of carbon monoxide (CO) at high spatiotemporal resolution with information on lowermost troposphere concentration. We present an OSSE to assess the improvement in surface CO characterization that would result from the addition of a GEO-CAPE CO measurement to current low Earth orbit (LEO) thermal infrared-only measurements. We construct instrument simulators for these two measurement scenarios and study the case of July 2004 when wildfires in Alaska and Canada led to significant CO pollution over the contiguous United States. Compared to a control experiment, an ensemble-based data assimilation of simulated satellite observations in a global model leads to improvements in both the surface CO distributions and the time evolution of CO profiles at locations affected by wildfire plumes and by urban emissions. In all cases, an experiment with the GEO-CAPE CO measurement scenario (overall model skill of 0.84) performed considerably better than the experiment with the current LEO/thermal infrared measurement (skill of 0.58) and the control (skill of 0.07). This demonstrates the advantages of increased sampling from GEO and enhanced measurement sensitivity to the lowermost troposphere with a multispectral retrieval.
Emmons, L. K., D. P. Edwards, M. N. Deeter, J. C. Gille, T. Campos, P. Nédélec, P. Novelli, and G. Sachse (2009), Measurements of Pollution In The Troposphere (MOPITT) validation through 2006, Atmos. Chem. Phys., 9(5), 1795–1803, doi:10.5194/acp-9-1795-2009.
Comparisons of aircraft measurements of carbon monoxide (CO) to the retrievals of CO using observations from the Measurements of Pollution in The Troposphere (MOPITT) instrument onboard the Terra satellite are presented. Observations made as part of the NASA INTEX-B and NSF MIRAGE field campaigns during March-May 2006 are used to validate the MOPITT CO retrievals, along with routine samples from 2001 through 2006 from NOAA and the MOZAIC measurements from commercial aircraft. A significant positive bias, around 20% for total column CO, in MOPITT CO was found in the comparison to in situ measurements during 2006. Comparisons to the long-term records of measurements from NOAA and MOZAIC revealed an increasing bias in the V3 MOPITT CO retrievals over time. The impact of an instrumental drift is illustrated through retrieval simulations.
Fortems-Cheiney, A., F. Chevallier, I. Pison, P. Bousquet, C. Carouge, C. Clerbaux, P.-F. Coheur, M. George, D. Hurtmans, and S. Szopa (2009), On the capability of IASI measurements to inform about CO surface emissions, Atmos. Chem. Phys., 9(22), 8735–8743, doi:10.5194/acp-9-8735-2009.
Between July and November 2008, simultaneous observations were conducted by several orbiting instruments that monitor carbon monoxide in the atmosphere, among them the Infrared Atmospheric Sounding Instrument (IASI) and Measurements Of Pollution In The Troposphere (MOPITT). In this paper, the concentration retrievals at about 700 hPa from these two instruments are successively used in a variational Bayesian system to infer the global distribution of CO emissions. Starting from a global emission budget of 479 Tg for the considered period, the posterior estimate of CO emissions using IASI retrievals gives a total of 643 Tg, which is in close agreement with the budget calculated with version 3 of the MOPITT data (649 Tg). The regional totals are also broadly consistent between the two inversions. Even though our theoretical error budget indicates that IASI constrains the emissions slightly less than MOPITT, because of lesser sensitivity in the lower troposphere, these first results indicate that IASI may play a major role in the quantification of the emissions of CO.
Freitas, S. R., K. M. Longo, M. A. F. Silva Dias, R. Chatfield, P. Silva Dias, P. Artaxo, M. O. Andreae, G. Grell, L. F. Rodrigues, A. Fazenda, and J. Panetta (2009), The Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS) – Part 1: Model description and evaluation, Atmos. Chem. Phys., 9(8), 2843–2861, doi:10.5194/acp-9-2843-2009.
We introduce the Coupled Aerosol and Tracer Transport model to the Brazilian developments on the Regional Atmospheric Modeling System (CATT-BRAMS). CATT-BRAMS is an on-line transport model fully consistent with the simulated atmospheric dynamics. Emission sources from biomass burning and urban-industrial-vehicular activities for trace gases and from biomass burning aerosol particles are obtained from several published datasets and remote sensing information. The tracer and aerosol mass concentration prognostics include the effects of sub-grid scale turbulence in the planetary boundary layer, convective transport by shallow and deep moist convection, wet and dry deposition, and plume rise associated with vegetation fires in addition to the grid scale transport. The radiation parameterization takes into account the interaction between the simulated biomass burning aerosol particles and short and long wave radiation. The atmospheric model BRAMS is based on the Regional Atmospheric Modeling System (RAMS), with several improvements associated with cumulus convection representation, soil moisture initialization and surface scheme tuned for the tropics, among others. In this paper the CATT-BRAMS model is used to simulate carbon monoxide and particulate material (PM2.5) surface fluxes and atmospheric transport during the 2002 LBA field campaigns, conducted during the transition from the dry to wet season in the southwest Amazon Basin. Model evaluation is addressed with comparisons between model results and near surface, radiosondes and airborne measurements performed during the field campaign, as well as remote sensing derived products. We show the matching of emissions strengths to observed carbon monoxide in the LBA campaign. A relatively good comparison to the MOPITT data, in spite of the fact that MOPITT a priori assumptions imply several difficulties, is also obtained.
George, M., C. Clerbaux, D. Hurtmans, S. Turquety, P.-F. Coheur, M. Pommier, J. Hadji-Lazaro, D. P. Edwards, H. Worden, M. Luo, C. Rinsland, and W. McMillan (2009), Carbon monoxide distributions from the IASI/METOP mission: evaluation with other space-borne remote sensors, Atmos. Chem. Phys., 9(21), 8317–8330, doi:10.5194/acp-9-8317-2009.
The Infrared Atmospheric Sounding Interferometer (IASI) onboard the MetOp satellite measures carbon monoxide (CO) on a global scale, twice a day. CO total columns and vertical profiles are retrieved in near real time from the nadir radiance spectra measured by the instrument in the thermal infrared (TIR) spectral range. This paper describes the measurement vertical sensitivity and provides a first assessment of the capabilities of IASI to measure CO distributions. On the global scale, 0.8 to 2.4 independent pieces of information are available for the retrieval. At mid latitudes, the information ranges between 1.5 and 2, which enables the lower and upper troposphere to be distinguished, especially when thermal contrast is significant. Global distributions of column CO are evaluated with correlative observations available from other nadir looking TIR missions currently in operation: the Measurements of Pollution in the Troposphere (MOPITT) onboard TERRA, the Atmospheric Infrared Sounder (AIRS) onboard AQUA and the Tropospheric Emission Spectrometer (TES) onboard AURA. The IASI CO columns are compared with MOPITT, AIRS and TES CO columns, adjusted with the a priori, for three different months: August 2008, November 2008 and February 2009. On average, total column discrepancies of about 7% are found between IASI and the three other sounders in the Northern Hemisphere and in the equatorial region. However when strong CO concentrations are present, such as during fire events, these discrepancies can climb as high as 17%. Instrument specifications of IASI versus other missions are also discussed.
Glatthor, N., T. von Clarmann, G. P. Stiller, B. Funke, M. E. Koukouli, H. Fischer, U. Grabowski, M. Höpfner, S. Kellmann, and A. Linden (2009), Large-scale upper tropospheric pollution observed by MIPAS HCN and C2H6 global distributions, Atmos. Chem. Phys., 9(24), 9619–9634, doi:10.5194/acp-9-9619-2009.
We present global upper tropospheric HCN and C2H6 amounts derived from MIPAS/ENVISAT limb emission spectra. HCN and C2H6 are retrieved in the spectral regions 715.5-782.7 cm-1 and 811.5-835.7 cm-1, respectively. The datasets consist of 54 days between September 2003 and March 2004. This period covers the peak and decline of the southern hemispheric biomass burning period and some months thereafter. HCN is a nearly unambiguous tracer of biomass burning with an assumed tropospheric lifetime of several months. Indeed, the most significant feature in the MIPAS HCN dataset is an upper tropospheric plume of enhanced values caused by southern hemispheric biomass burning, which in September and October 2003 extended from tropical South America over Africa, Australia to the Southern Pacific. The spatial extent of this plume agrees well with the MOPITT CO distribution of September 2003. Further there is good agreement with the shapes and mixing ratios of the southern hemispheric HCN and C2H6 fields measured by the ACE experiment between September and November 2005. The MIPAS HCN plume extended from the lowermost observation height of 8 km up to about 16 km altitude, with maximum values of 500-600 pptv in October 2003. It was still clearly visible in December 2003, but had strongly decreased by March 2004, confirming the assumed tropospheric lifetime. The main sources of C2H6 are production and transmission of fossil fuels, followed by biofuel use and biomass burning. The C2H6 distribution also clearly reflected the southern hemispheric biomass burning plume and its seasonal variation, with maximum amounts of 600-700 pptv. Generally there was good spatial overlap between the southern hemispheric distributions of both pollution tracers, except for the region between Peru and the mid-Pacific. Here C2H6was considerably enhanced, whereas the HCN amounts were low. Backward trajectory calculations suggested that industrial pollution was responsible for the elevated C2H6 concentration in these particular air masses. Except for the Asian monsoon anticyclone in September 2003, there were only comparably small regions of enhanced HCN in the Northern Hemisphere. However, C2H6 showed an equally strong northern hemispheric signal between the equator and low midlatitudes, persisting over the whole observation period. Backward trajectory calculations for air masses from this region also point to industrial sources of this pollution. Generally, C2H6/HCN ratios between 1 and 1.5 indicate biomass burning and ratios larger than 1.5 industrial pollution. However, in March 2004 ratios of up to 2 were also found in some regions of the former southern biomass burning plume.
Gloudemans, A. M. S., A. T. J. de Laat, H. Schrijver, I. Aben, J. F. Meirink, and G. R. van der Werf (2009), SCIAMACHY CO over land and oceans: 2003–2007 interannual variability, Atmos. Chem. Phys., 9(11), 3799–3813, doi:10.5194/acp-9-3799-2009.
We present a new method to obtain accurate SCIAMACHY CO columns over clouded ocean scenes. Based on an improved version of the Iterative Maximum Likelihood Method (IMLM) retrieval algorithm, we now have retrieved five years of data over both land and clouded ocean scenes between 2003 and 2007. The ocean-cloud method uses the CH4 columns retrieved simultaneously with the CO columns to determine the cloud top height. The CH4 cloud top height is in good agreement with the FRESCO+ cloud top height determined from UV-VIS oxygen-A band measurements, providing confidence that the CH4 cloud top height is a good diagnostic of the cloud top height over (partially) clouded ocean scenes. The CO measurements over clouded ocean scenes have been compared with collocated modeled CO columns over the same clouds and agree well. Using clouded ocean scenes quadruples the number of useful CO measurements compared to land-only measurements.
Ho, S.-P., D. P. Edwards, J. C. Gille, M. Luo, G. B. Osterman, S. S. Kulawik, and H. Worden (2009), A global comparison of carbon monoxide profiles and column amounts from Tropospheric Emission Spectrometer (TES) and Measurements of Pollution in the Troposphere (MOPITT), Journal of Geophysical Research: Atmospheres, 114(D21), n/a–n/a, doi:10.1029/2009JD012242.
In this study, we compare carbon monoxide (CO) products from the Measurements of Pollution in the Troposphere (MOPITT) and Tropospheric Emission Spectrometer (TES) and investigate the possible causes of the differences between retrievals for these two data sets. Direct comparisons of CO retrievals for July 2006 show that TES CO concentrations are consistently biased lower than those of MOPITT by 25 ppbv near the surface and by 20 ppbv at 150 hPa, primarily due to different a priori profiles and covariance matrices used in the TES and MOPITT CO retrievals. To reduce the effects of different a priori constraints, we apply TES a priori profiles and covariance matrices to a modified MOPITT retrieval algorithm. The mean TES-MOPITT CO difference decreases from −25 to −10 ppbv near the surface. To further account for retrieval smoothing errors due to different TES and MOPITT averaging kernels, TES averaging kernels are used to smooth MOPITT CO profiles to derive TES-equivalent CO profiles. Compared to these, TES CO profiles are biased 1 ppbv lower near the surface and 4–9 ppbv lower in the troposphere, and the mean absolute TES and TES-equivalent CO column difference is less than 6.5%. The mean TES and MOPITT CO differences due to smoothing errors are close to zero, and the remaining bias is primarily due to the combined effects of radiance biases, forward model errors, and the spatial and temporal mismatches of TES and MOPITT pixels.
Isaksen, I. S. A., C. Granier, G. Myhre, T. K. Berntsen, S. B. Dalsøren, M. Gauss, Z. Klimont, R. Benestad, P. Bousquet, W. Collins, T. Cox, V. Eyring, D. Fowler, S. Fuzzi, P. Jöckel, P. Laj, U. Lohmann, M. Maione, P. Monks, A. S. H. Prevot, F. Raes, A. Richter, B. Rognerud, M. Schulz, D. Shindell, D. S. Stevenson, T. Storelvmo, W.-C. Wang, M. van Weele, M. Wild, and D. Wuebbles (2009), Atmospheric composition change: Climate–Chemistry interactions, Atmospheric Environment, 43(33), 5138–5192, doi:10.1016/j.atmosenv.2009.08.003.
Chemically active climate compounds are either primary compounds like methane (CH4), removed by oxidation in the atmosphere, or secondary compounds like ozone (O3), sulfate and organic aerosols, both formed and removed in the atmosphere. Man-induced climate–chemistry interaction is a two-way process: Emissions of pollutants change the atmospheric composition contributing to climate change through the aforementioned climate components, and climate change, through changes in temperature, dynamics, the hydrological cycle, atmospheric stability, and biosphere-atmosphere interactions, affects the atmospheric composition and oxidation processes in the troposphere. Here we present progress in our understanding of processes of importance for climate–chemistry interactions, and their contributions to changes in atmospheric composition and climate forcing. A key factor is the oxidation potential involving compounds like O3 and the hydroxyl radical (OH). Reported studies represent both current and future changes. Reported results include new estimates of radiative forcing based on extensive model studies of chemically active climate compounds like O3, and of particles inducing both direct and indirect effects. Through EU projects like ACCENT, QUANTIFY, and the AeroCom project, extensive studies on regional and sector-wise differences in the impact on atmospheric distribution are performed. Studies have shown that land-based emissions have a different effect on climate than ship and aircraft emissions, and different measures are needed to reduce the climate impact. Several areas where climate change can affect the tropospheric oxidation process and the chemical composition are identified. This can take place through enhanced stratospheric–tropospheric exchange of ozone, more frequent periods with stable conditions favoring pollution build up over industrial areas, enhanced temperature induced biogenic emissions, methane releases from permafrost thawing, and enhanced concentration through reduced biospheric uptake. During the last 5–10 years, new observational data have been made available and used for model validation and the study of atmospheric processes. Although there are significant uncertainties in the modeling of composition changes, access to new observational data has improved modeling capability. Emission scenarios for the coming decades have a large uncertainty range, in particular with respect to regional trends, leading to a significant uncertainty range in estimated regional composition changes and climate impact.
Jones, D. B. A., K. W. Bowman, J. A. Logan, C. L. Heald, J. Liu, M. Luo, J. Worden, and J. Drummond (2009), The zonal structure of tropical O3 and CO as observed by the Tropospheric Emission Spectrometer in November 2004 – Part 1: Inverse modeling of CO emissions, Atmos. Chem. Phys., 9(11), 3547–3562, doi:10.5194/acp-9-3547-2009.
We conduct an inverse modeling analysis of measurements of atmospheric CO from the TES and MOPITT satellite instruments using the GEOS-Chem global chemical transport model to quantify emissions of CO in the tropics in November 2004. We also assess the consistency of the information provided by TES and MOPITT on surface emissions of CO. We focus on the tropics in November 2004, during the biomass burning season., because TES observations of CO and O-3 and MOPITT observations of CO reveal significantly greater abundances of these gases than simulated by the GEOS-Chem model during that period. We find that both datasets suggest substantially greater emissions of CO from sub-equatorial Africa and the Indonesian/Australian re-ion than in the climatological emissions in the model. The a posteriori emissions from sub-equatorial Africa based on TES and MOPITT data were 173 Tg CO/yr and 184 Tg CO/yr, respectively, compared to the a priori of 95 Tg CO/yr. In the Indonesian/Australian region, the a posteriori emissions inferred from TES and MOPITT data were 155 Tg CO/yr and 185 Tg CO/yr, respectively, whereas the a priori was 69 Tg CO/yr. The differences between the a posteriori emission estimates obtained from the two datasets are generally less than 20%. The a posteriori emissions significantly improve the simulated distribution of CO, however, large regional residuals remain, and are likely due to systematic errors in the analysis. Reducing these residuals and improving the accuracy of top-down emission estimates will require better characterization of systematic errors in the observations and the model (chemistry and transport).
Khlystova, I., M. Buchwitz, J. P. Burrows, H. Bovensmann, and D. Fowler (2009), Carbon monoxide spatial gradients over source regions as observed by  SCIAMACHY: A case study for the United Kingdom, Adv. Space Res., 43(6), 923–929, doi:10.1016/j.asr.2008.10.012.
Carbon monoxide (CO) is an important air pollutant whose emissions and atmospheric concentrations need to be monitored. The measurements of the SCIAMACHY instrument oil ENVISAT are sensitive to CO concentration changes at all atmospheric altitude levels including the boundary layer. The SCIAMACHY CO measurements therefore contain information on CO emissions. Until now no studies have been published where the SCIAMACHY CO measurements have been used to quantify CO emissions by applying, for example, inverse modelling approaches. Here we report about a step in this direction. We have analysed three years of CO columns to investigate if spatial gradients resulting from United Kingdom (UK) CO emissions can be observed from space. The UK is an interesting target area because the UK is a relatively well isolated CO source region. Oil the other hand, the UK is not the easiest target as its emissions are only moderate and because the surrounding water has low reflectivity in the 2.3 mu m spectral region used for CO retrieval. We determined horizontal CO gradients from seasonally and yearly averaged CO during 2003-2005 over the UK taking into account daily wind fields. We show that the measured CO longitudinal (downwind) gradients have the expected order of magnitude. The estimated 2 sigma error of the gradients depends on time period and applied filtering criteria (e.g., land only, cloud free) and is typically 10-20% of the total column. The gradients are barely statistically significant within the 2 sigma error margin. This is mainly because of the relatively high noise of the SCIAMACHY CO measurements in combination with a quite low number of measurements (similar to 100) mainly due to cloud cover. (C) 2008 COSPAR. Published by Elsevier Ltd. All rights reserved.
Kopacz, M., D. J. Jacob, D. K. Henze, C. L. Heald, D. G. Streets, and Q. Zhang (2009), Comparison of adjoint and analytical Bayesian inversion methods for constraining Asian sources of carbon monoxide using satellite (MOPITT) measurements of CO columns, Journal of Geophysical Research (Atmospheres), 114(d13), 4305, doi:10.1029/2007JD009264.
We apply the adjoint of an atmospheric chemical transport model (GEOS-Chem CTM) to constrain Asian sources of carbon monoxide (CO) with 2° × 2.5° spatial resolution using Measurement of Pollution in the Troposphere (MOPITT) satellite observations of CO columns in February-April 2001. Results are compared to the more common analytical method for solving the same Bayesian inverse problem and applied to the same data set. The analytical method is more exact but because of computational limitations it can only constrain emissions over coarse regions. We find that the correction factors to the a priori CO emission inventory from the adjoint inversion are generally consistent with those of the analytical inversion when averaged over the large regions of the latter. The adjoint solution reveals fine-scale variability (cities, political boundaries) that the analytical inversion cannot resolve, for example, in the Indian subcontinent or between Korea and Japan, and some of that variability is of opposite sign which points to large aggregation errors in the analytical solution. Upward correction factors to Chinese emissions from the prior inventory are largest in central and eastern China, consistent with a recent bottom-up revision of that inventory, although the revised inventory also sees the need for upward corrections in southern China where the adjoint and analytical inversions call for downward correction. Correction factors for biomass burning emissions derived from the adjoint and analytical inversions are consistent with a recent bottom-up inventory on the basis of MODIS satellite fire data.
Pison, I., P. Bousquet, F. Chevallier, S. Szopa, and D. Hauglustaine (2009), Multi-species inversion of CH4, CO and H2 emissions from surface measurements, Atmos. Chem. Phys., 9(14), 5281–5297, doi:10.5194/acp-9-5281-2009.
In order to study the spatial and temporal variations of the emissions of greenhouse gases and of their precursors, we developed a data assimilation system and applied it to infer emissions of CH4, CO and H-2 for one year. It is based on an atmospheric chemical transport model and on a simplified scheme for the oxidation chain of hydrocarbons, including methane, formaldehyde, carbon monoxide and molecular hydrogen together with methyl chloroform. The methodology is exposed and a first attempt at evaluating the inverted fluxes is made. Inversions of the emission fluxes of CO, CH4 and H-2 and concentrations of HCHO and OH were performed for the year 2004, using surface concentration measurements of CO, CH4, H-2 and CH3CCl3 as constraints. Independent data from ship and aircraft measurements and satellite retrievals are used to evaluate the results. The total emitted mass of CO is 30% higher after the inversion, due to increased fluxes by up to 35% in the Northern Hemisphere. The spatial distribution of emissions of CH4 is modified by a decrease of fluxes in boreal areas up to 60%. The comparison between mono- and multi-species inversions shows that the results are close at a global scale but may significantly differ at a regional scale because of the interactions between the various tracers during the inversion.
Reidmiller, D. R., D. A. Jaffe, D. Chand, S. Strode, P. Swartzendruber, G. M. Wolfe, and J. A. Thornton (2009), Interannual variability of long-range transport as seen at the Mt. Bachelor observatory, Atmos. Chem. Phys., 9(2), 557–572, doi:10.5194/acp-9-557-2009.
Interannual variations in background tropospheric trace gases (such as carbon monoxide, CO) are largely driven by variations in emissions (especially wildfires) and transport pathways. Understanding this variability is essential to quantify the intercontinental contribution to US air quality. We investigate the interannual variability of long-range transport of Asian pollutants to the Northeast Pacific via measurements from the Mt. Bachelor Observatory (MBO: 43.98° N, 121.69° W; 2.7 km a.s.l.) and GEOS-Chem chemical transport model simulations in spring 2005 vs. the INTEX-B campaign during spring 2006. Measurements of CO at MBO were significantly enhanced during spring 2005 relative to the same time in 2006 (the INTEX-B study period); a decline in monthly mean CO of 41 ppbv was observed between April 2005 and April 2006. A backtrajectory-based meteorological index shows that long-range transport of CO from the heavily industrialized region of East Asia was significantly greater in early spring 2005 than in 2006. In addition, spring 2005 was an anomalously strong biomass burning season in Southeast Asia. Data presented by Yurganov et al. (2008) using MOPITT satellite retrievals from this area reveal an average CO burden anomaly (referenced to March 2000-February 2002 mean values) between October 2004 through April 2005 of 2.6 Tg CO vs. 0.6 Tg CO for the same period a year later. The Naval Research Laboratory’s global aerosol transport model, as well as winds from NCEP reanalysis, show that emissions from these fires were efficiently transported to MBO throughout April 2005. Asian dust transport, however, was substantially greater in 2006 than 2005, particularly in May. Monthly mean aerosol light scattering coefficient at 532 nm (σsp) at MBO more than doubled from 2.7 Mm-1 in May 2005 to 6.2 Mm-1 in May 2006. We also evaluate CO interannual variability throughout the western US via Earth System Research Laboratory ground site data and throughout the Northern Hemisphere via MOPITT and TES satellite observations. Both in the Northeast Pacific and on larger scales, we reveal a significant decrease (from 2-21%) in springtime maximum CO between 2005 and 2006, evident in all platforms and the GEOS-Chem model. We attribute this to (a) anomalously strong biomass burning in Southeast Asia during winter 2004 through spring 2005, and (b) the transport pattern in March and April 2006 which limited the inflow of Asian pollution to the lower free troposphere over western North America.
Shukla, B. P., and Ajai (2009), Retrieval of Carbon monoxide profiles over Indian region using MOPITT data, Atmospheric Environment, 43(22–23), 3472–3480, doi:10.1016/j.atmosenv.2009.04.037.
Vertical profiles of carbon monoxide (CO) over the Indian region have scarcely been monitored. Satellite sensor, Measurement Of Pollution In The Troposphere (MOPITT) provides profiles of CO using a global retrieval scheme, which converts measured radiances to CO mixing ratios. In this study we have developed a regional retrieval scheme, valid over the Indian region, which employs Line-By-Line (LBL) calculations over a tropical model atmosphere to generate a Look-Up-Table (LUT) forward model function and uses a regional a priori dataset of CO along with seasonally variable emissivity to invert the MOPITT radiances to CO profiles. This baseline study provides an approach to optimizing retrievals for specific regional applications. A case study was carried out over a forest fire prone region in Northern India from February to April 2005 to validate the retrieval algorithm. The results are in agreement with the fire maps generated from MODerate resolution Imaging Spectro-radiometer (MODIS). The shape of the CO profiles over the region matches quite well with the vertical structure of CO during the INDOEX campaign, especially during the polluted month of April. Inter-comparisons with the MOPITT data product indicate some discrepancies in the lower troposphere, especially during the forest fire season. Future studies with in-situ measurements may be able to diagnose these disparities.
Stremme, W., I. Ortega, and M. Grutter (2009), Using ground-based solar and lunar infrared spectroscopy to study the diurnal trend of carbon monoxide in the Mexico City boundary layer, Atmos. Chem. Phys., 9(20), 8061–8078, doi:10.5194/acp-9-8061-2009.
Carbon monoxide (CO) is an important pollutant in urban agglomerations. Quantifying the total burden of this pollutant in a megacity is challenging because not only its surface concentration but also its vertical dispersion present different behaviours and high variability. The diurnal trend of columnar CO in the boundary layer of Mexico City has been measured during various days with ground-based infrared absorption spectroscopy. Daytime CO total columns are retrieved from solar spectra and for the first time, nocturnal CO total columns using moonlight have been retrieved within a megacity. The measurements were taken at the Universidad Nacional Autonoma de Mexico (UNAM) campus located in Mexico City (19.33 degree N, 99.18 degree W, 2260 m a.s.l.) from October 2007 until February 2008 with a Fourier-transform infrared spectrometer at 0.5 cm super(− 1) resolution. The atmospheric CO background column was measured from the high altitude site Altzomoni (19.12 degree N, 98.65 degree W, 4010 m a.s.l.) located 60 km southeast of Mexico City. The total CO column within the city presents large variations. Fresh CO emissions at the surface, the transport of cleaner or more polluted air masses within the field-of-view of the instrument and other processes contribute to this variability. The mean background value above the boundary mixing layer was found to be (8.4 plus or minus 0.5)10 super(17) molecules/cm super(2), while inside the city, the late morning mean on weekdays and Sundays was found to be (2.73 plus or minus 0.41)10 super(18) molecules/cm super(2) and (2.04 plus or minus 0.57)10 super(18) molecules/cm super(2), respectively. Continuous CO column retrieval during the day and night (when available), in conjunction with surface CO measurements, allow for a reconstruction of the effective mixing layer height. The limitations from this simplified approach, as well as the potential of using continuous column measurements in order to derive top-down CO emissions from a large urban area, are discussed. Also, further monitoring will provide more insight in daily and weekly emission patterns and a usable database for the quantitative validation of CO from satellite observations in a megacity.
Tangborn, A., I. Stajner, M. Buchwitz, I. Khlystova, S. Pawson, J. Burrows, R. Hudman, and P. Nedelec (2009), Assimilation of SCIAMACHY total column CO observations: Global and regional analysis of data impact, J. Geophys. Res.-Atmos., 114(D7), n/a–n/a, doi:10.1029/2008JD010781.
Carbon monoxide (CO) total column observations from the Scanning Imaging Absorption Spectrometer for Atmospheric Cartography (SCIAMACHY) on board Envisat-1 are assimilated into the Global Modeling and Assimilation Office constituent assimilation system for the period 1 April to 20 December 2004. The impact of the assimilation on CO distribution is evaluated using independent surface flask observations from the National Oceanic and Atmospheric Administration (NOAA)/ESRL global cooperative air sampling network and Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) in situ CO profiles. Assimilation of SCIAMACHY data improves agreement of CO assimilation with both of these data sets on both global and regional scales compared to the free-running model. Regional comparisons with MOZAIC profiles made in western Europe, the northeastern United States, and the Arabian Peninsula show improvements at all three locations in the free troposphere and into the boundary layer over Arabia and the northeastern United States. Comparisons with NOAA Earth System Research Laboratory data improve at about two thirds of the surface observation sites. The systematic model errors related to the uncertainty of CO surface sources and the chemistry of CO losses are investigated through experiments with increased surface CO emissions over the Arabian Peninsula and/or globally reduced hydroxyl radical (OH) concentrations. Both model changes decrease mean CO errors at all altitudes in comparison to MOZAIC data over Dubai and Abu Dhabi. In contrast, errors in the assimilated CO are reduced by the increased emissions for pressures ≥800 hPa and by the reduced OH for pressures ≤600 hPa. Our analysis suggests that CO emissions over Dubai in 2004 are more than double those in the 1998 emissions inventory.
Turquety, S., D. Hurtmans, J. Hadji-Lazaro, P.-F. Coheur, C. Clerbaux, D. Josset, and C. Tsamalis (2009), Tracking the emission and transport of pollution from wildfires using the IASI CO retrievals: analysis of the summer 2007 Greek fires, Atmos. Chem. Phys., 9(14), 4897–4913, doi:10.5194/acp-9-4897-2009.
In this paper, we analyze the performance of the Infrared Atmospheric Sounding Interferometer (IASI), launched in October 2006 on board METOP-A, for the monitoring of carbon monoxide (CO) during extreme fire events, focusing on the record-breaking fires which devastated thousands of square kilometers of forest in Greece during the last week (23-30) of August 2007. After an assessment of the quality of the profiles retrieved using the Fast Optimal Retrievals on Layers for IASI (FORLI) algorithm, the information provided on fire emissions and subsequent pollution outflow is discussed. Large CO plumes were observed above the Mediterranean Basin and North Africa, with total CO columns exceeding 24x10(18) molecules/cm(2) and absolute volume mixing ratios up to 4 ppmv on the 25 August. Up to 30x10(18) molecules/cm(2) and 22 ppmv in the lower troposphere are retrieved close to the fires above the Peloponnese, but with larger uncertainty. The average root-mean-square (RMS) difference between simulated and observed spectra is close to the estimated radiometric noise level, slightly increasing (by similar to 14%) in the fresh fire plumes. CO profiles are retrieved with a vertical resolution of about 8 km, with similar to 1.7 pieces of independent information on the vertical in the region considered and a maximum sensitivity in the free troposphere (similar to 4-5 km). Using the integrated total amount, the increase in CO burden due to these fires is estimated to 0.321 Tg, similar to 40% of the total annual anthropogenic emissions in Greece. The patterns of these CO enhancements are in good agreement with the aerosol optical depth (AOD) retrieved from the MODIS measurements, highlighting a rapid transport of trace gases and aerosols across the Mediterranean Basin (less than one day). While the coarse vertical resolution will not allow the location of the exact plume height, the large CO enhancements observed in the lower troposphere are consistent with the maximum aerosol backscatter coefficient at similar to 2 km detected by the CALIPSO lidar in space (CALIOP).

2008

Clerbaux, C., D. P. Edwards, M. Deeter, L. Emmons, J.-F. Lamarque, X. X. Tie, S. T. Massie, and J. Gille (2008a), Carbon monoxide pollution from cities and urban areas observed by the Terra/MOPITT mission, Geophysical Research Letters, 35(3), n/a–n/a, doi:10.1029/2007GL032300.
Carbon monoxide (CO) is a key species for tracking pollution plumes. The Measurement Of Pollution in The Troposphere (MOPITT) mission onboard the Terra satellite has already provided 7.5 years of CO atmospheric concentration measurements around the globe. Limited sensitivity to the boundary layer is well known to be a weakness of nadir looking thermal infrared sounders. This paper investigates the possibility of using the MOPITT surface measurements to detect CO emitted by cities and urban centers. By selecting the data and averaging them over long time periods, we demonstrate that the CO pollution arising from the large cities and urban areas can be distinguished from the background transported pollution. The more favorable observations are obtained during daytime and at locations where the thermal contrast (temperature gradient) between the surface and lower atmosphere is significant.
Clerbaux, C., M. George, S. Turquety, K. A. Walker, B. Barret, P. Bernath, C. Boone, T. Borsdorff, J. P. Cammas, V. Catoire, M. Coffey, P.-F. Coheur, M. Deeter, M. De Mazière, J. Drummond, P. Duchatelet, E. Dupuy, R. de Zafra, F. Eddounia, D. P. Edwards, L. Emmons, B. Funke, J. Gille, D. W. T. Griffith, J. Hannigan, F. Hase, M. Höpfner, N. Jones, A. Kagawa, Y. Kasai, I. Kramer, E. Le Flochmoën, N. J. Livesey, M. López-Puertas, M. Luo, E. Mahieu, D. Murtagh, P. Nédélec, A. Pazmino, H. Pumphrey, P. Ricaud, C. P. Rinsland, C. Robert, M. Schneider, C. Senten, G. Stiller, A. Strandberg, K. Strong, R. Sussmann, V. Thouret, J. Urban, and A. Wiacek (2008b), CO measurements from the ACE-FTS satellite instrument: data analysis and validation using ground-based, airborne and spaceborne observations, Atmos. Chem. Phys., 8(9), 2569–2594, doi:10.5194/acp-8-2569-2008.
The Atmospheric Chemistry Experiment (ACE) mission was launched in August 2003 to sound the atmosphere by solar occultation. Carbon monoxide (CO), a good tracer of pollution plumes and atmospheric dynamics, is one of the key species provided by the primary instrument, the ACE-Fourier Transform Spectrometer (ACE-FTS). This instrument performs measurements in both the CO 1-0 and 2-0 ro-vibrational bands, from which vertically resolved CO concentration profiles are retrieved, from the mid-troposphere to the thermosphere. This paper presents an updated description of the ACE-FTS version 2.2 CO data product, along with a comprehensive validation of these profiles using available observations (February 2004 to December 2006). We have compared the CO partial columns with ground-based measurements using Fourier transform infrared spectroscopy and millimeter wave radiometry, and the volume mixing ratio profiles with airborne (both high-altitude balloon flight and airplane) observations. CO satellite observations provided by nadir-looking instruments (MOPITT and TES) as well as limb-viewing remote sensors (MIPAS, SMR and MLS) were also compared with the ACE-FTS CO products. We show that the ACE-FTS measurements provide CO profiles with small retrieval errors (better than 5% from the upper troposphere to 40 km, and better than 10% above). These observations agree well with the correlative measurements, considering the rather loose coincidence criteria in some cases. Based on the validation exercise we assess the following uncertainties to the ACE-FTS measurement data: better than 15% in the upper troposphere (8–12 km), than 30% in the lower stratosphere (12–30 km), and than 25% from 30 to 100 km.
Guan, H., R. B. Chatfield, S. R. Freitas, R. W. Bergstrom, and K. M. Longo (2008), Modeling the effect of plume-rise on the transport of carbon monoxide over Africa with NCAR CAM, Atmos. Chem. Phys., 8(22), 6801–6812, doi:10.5194/acp-8-6801-2008.
We investigated the effects of fire-induced plume-rise on the simulation of carbon monoxide (CO) over Africa and its export during SAFARI 2000 using the NCAR Community Atmosphere Model (CAM) with a CO tracer and a plume-rise parameterization scheme. The plume-rise parameterization scheme simulates the consequences of strong buoyancy of hot gases emitted from biomass burning, including both dry and cloud-associated (pyro-cumulus) lofting. The current implementation of the plume-rise parameterization scheme into the global model provides an opportunity to examine the effect of plume-rise on long-range transport. The CAM simulation with the plume-rise parameterization scheme seems to show a substantial improvement of the agreements between the modeled and aircraft-measured vertical distribution of CO over Southern Africa biomass-burning area. The plume-rise mechanism plays a crucial role in lofting biomass-burning pollutants to the middle troposphere. In the presence of deep convection we found that the plume-rise mechanism results in a decrease of CO concentration in the upper troposphere. The plume-rise depletes the boundary layer, and thus leaves lower concentrations of CO to be lofted by the deep convection process. The effect of the plume-rise on free troposphere CO concentration is more important for the source area (short-distance transport) than for remote areas (long-distance transport). A budget analysis of CO burden over Southern Africa reveals the plume-rise process to have a similar impact as the chemical production of CO by OH and CH4. In addition, the plume-rise process has an minor impact on the regional export. These results further confirm and extend previous findings in a regional model study. Effective lofting of large concentration of CO by the plume-rise mechanism also has implications for local air quality forecasting in areas affected by other fire-related pollutants.
Henne, S., J. Klausen, W. Junkermann, J. M. Kariuki, J. O. Aseyo, and B. Buchmann (2008), Representativeness and climatology of carbon monoxide and ozone at the global GAW station Mt. Kenya in equatorial Africa, Atmos. Chem. Phys., 8(12), 3119–3139, doi:10.5194/acp-8-3119-2008.
The tropics strongly influence the global atmospheric chemistry budget. However, continuous in-situ observations of trace gases are rare especially in equatorial Africa. The WMO Global Atmosphere Watch (GAW) programme aimed to close this gap with the installation of the Mt. Kenya (MKN) baseline station. Here, the first continuous measurements of carbon monoxide (CO) and ozone (O3) at this site covering the period June 2002 to June 2006 are presented. The representativeness of the site was investigated by means of statistical data analysis, air mass trajectory clustering, interpretation of biomass burning variability and evaluation of O3-CO relationships. Because of its location in eastern equatorial Africa, the site was rarely directly influenced by biomass burning emissions, making it suitable for background observations. Located at 3678m above sea level the night-time (21:00–04:00 UTC) measurements of CO and O3 were in general representative of the free troposphere, while day-time measurements were influenced by atmospheric boundary layer air. Increased night-time concentrations were observed in 25% of all nights and associated with residual layers of increased CO and water vapour in the free troposphere. Six representative flow regimes towards Mt. Kenya were determined: eastern Africa (21% of the time), Arabian Peninsula and Pakistan (16%), northern Africa free tropospheric (6%), northern Indian Ocean and India (17%), south-eastern Africa (18%) and southern India Ocean (21%) flow regimes. The seasonal alternation of these flow regimes was determined by the monsoon circulation and caused a distinct semi-annual cycle of CO with maxima during February (primary) and August (secondary, annually variable) and with minima in April (primary) and November (secondary, annually variable). O3 showed a weaker annual cycle with a minimum in November and a broad sum- Correspondence to: S. Henne (stephan.henne@empa.ch) mer maximum. Inter-annual variations were explained with differences in southern African biomass burning and transport towards MKN. Although biomass burning had little direct influence on the measurements at MKN it introduces inter-annual variability in the background concentrations of the southern hemisphere that subsequently reaches Kenya. The measurements atMKN were representative of air masses with little photochemical activity as indicated by weak O3- CO correlations, underlining the baseline character of the site. Inter-comparison of O3 at MKN with sounding data from Nairobi revealed a positive offset of the sounding data, most likely due to additional photochemical production of O3 in the Nairobi city plume. Future extensions of the measurement programme will provide better understanding of the atmospheric chemistry of this globally important region.
Kaminski, J. W., L. Neary, J. Struzewska, J. C. McConnell, A. Lupu, J. Jarosz, K. Toyota, S. L. Gong, J. Côté, X. Liu, K. Chance, and A. Richter (2008), GEM-AQ, an on-line global multiscale chemical weather modelling system: model description and evaluation of gas phase chemistry processes, Atmos. Chem. Phys., 8(12), 3255–3281, doi:10.5194/acp-8-3255-2008.
Tropospheric chemistry and air quality processes were implemented on-line in the Global Environmental Multiscale weather prediction model. The integrated model, GEM-AQ, was developed as a platform to investigate chemical weather at scales from global to urban. The current chemical mechanism is comprised of 50 gas-phase species, 116 chemical and 19 photolysis reactions, and is complemented by a sectional aerosol module with 5 aerosols types. All tracers are advected using the semi-Lagrangian scheme native to GEM. The vertical transport includes parameterized subgrid-scale turbulence and large scale deep convection. Dry deposition is included as a flux boundary condition in the vertical diffusion equation. Wet deposition of gas-phase species is treated in a simplified way, and only below-cloud scavenging is considered. The emissions used include yearly-averaged anthropogenic, and monthly-averaged biogenic, ocean, soil, and biomass burning emission fluxes, as well as NOx from lightning. In order to evaluate the ability to simulate seasonal variations and regional distributions of trace gases such as ozone, nitrogen dioxide and carbon monoxide, the model was run for a period of five years (2001-2005) on a global uniform 1.5 degrees x 1.5 degrees horizontal resolution domain and 28 hybrid levels extending up to 10 hPa. Model results were compared with observations from satellites, aircraft measurement campaigns and balloon sondes. We find that GEM-AQ is able to capture the spatial details of the chemical fields in the middle and lower troposphere. The modelled ozone consistently shows good agreement with observations, except over tropical oceans. The comparison of carbon monoxide and nitrogen dioxide with satellite measurements emphasizes the need for more accurate, year-specific emissions fluxes for biomass burning and anthropogenic sources. Other species also compare well with available observations.
Kar, J., D. B. A. Jones, J. R. Drummond, J. L. Attié, J. Liu, J. Zou, F. Nichitiu, M. D. Seymour, D. P. Edwards, M. N. Deeter, J. C. Gille, and A. Richter (2008), Measurement of low-altitude CO over the Indian subcontinent by MOPITT, Journal of Geophysical Research (Atmospheres), 113(d12), 16307, doi:10.1029/2007JD009362.
We show that the dayside MOPITT retrievals in the lower troposphere can provide useful information on surface sources of atmospheric CO over the Indian subcontinent. We find that MOPITT retrievals at 850 hPa show localized enhancements over the Indian subcontinent, which correlate with similar enhancements seen in the tropospheric NO2 columns from the SCIAMACHY instrument. In particular, high concentrations of CO over the Indo-Gangetic basin and some prominent cities are captured in the lower-tropospheric retrievals in spring. MOPITT averaging kernels (normalized to take into account the absorber amounts in the layers) indicate that the retrievals are sensitive to CO in the lower troposphere. In winter, MOPITT retrievals at 850 hPa can detect the strongest source areas over the eastern states of Bihar and West Bengal, thus confirming the so-called “Bihar pollution pool,” which was detected earlier in the aerosol measurements by the multiangle imaging spectroradiometer (MISR) aboard Terra. The pollution features are consistent with the spatial distribution of CO emissions in India, as reflected in the GEOS-Chem simulation of CO. Furthermore, these lower-tropospheric features in the simulation are still present after smoothing the modeled fields using the MOPITT averaging kernels and a priori profile, demonstrating that the retrievals do have sensitivity in the lower troposphere. This work indicates that although MOPITT retrievals are often most sensitive to CO in the middle and upper troposphere, they do provide information on lower-tropospheric CO in selected continental regions with strong thermal contrast and could be useful for pollution studies.
Kim, J. H., S. Na, R. V. Martin, K. H. Seo, and M. J. Newchurch (2008), Singular value decomposition analyses of tropical tropospheric ozone determined from TOMS, Geophysical Research Letters, 35(15), n/a–n/a, doi:10.1029/2008GL033690.
A controversial dispute in space-based tropospheric ozone remote sensing is the puzzling discrepancy in the spatiotemporal distribution between residual-based satellite ozone observations and biomass-burning activity in the tropics during boreal winter. This study focuses on evaluation and analyses of two tropospheric ozone products determined from Earth Probe TOMS measurements: Convective Cloud Differential measurements (CCD) and Scan Angle measurements (SAM). Rather than using the typical station-to-station inter-comparison with ozone sounding measurements, the evaluation was performed at the global scale using temporal and spatial patterns derived from Singular Value Decomposition (SVD) analyses. The satellite observations of ozone precursors from MOPITT CO and GOME NO2 serve as markers identifying airmasses influenced by biomass burning. The SVD analyses reveal that the SAM tropospheric ozone product is remarkably consistent (95% significance level) with the two measured ozone precursors, CO and NO2, in distribution as well as in seasonality. The analyses provide compelling evidence that there is no discrepancy between tropospheric ozone and its precursors during boreal winter.
Mari, C. H., G. Cailley, L. Corre, M. Saunois, J. L. Attié, V. Thouret, and A. Stohl (2008), Tracing biomass burning plumes from the Southern Hemisphere during the  AMMA 2006 wet season experiment, Atmos. Chem. Phys., 8(14), 3951–3961, doi:10.5194/acp-8-3951-2008.
The Lagrangian particle dispersion model FLEXPART coupled with daily active fire products provided by the MODIS instrument was used to forecast the intrusions of the southern hemispheric fire plumes in the Northern Hemisphere during the AMMA (African Monsoon Multidisciplinary Analysis) fourth airborne campaign from 25 July to 31 August 2006 (Special Operation Period SOP2_a2). The imprint of the biomass burning plumes over the Gulf of Guinea showed a well marked intraseasonal variability which is controlled by the position and strength of the southern hemispheric African Easterly Jet (AEJ-S). Three different periods were identified which correspond to active and break phases of the AEJ-S: 25 July 2 August (active phase), 3 August 8 August (break phase) and 9 August 31 August (active phase). During the AEJ-S active phases, the advection of the biomass burning plumes out over the Atlantic ocean was efficient in the mid-troposphere. During the AEJ-S break phases, pollutants emitted by fires were trapped over the continent where they accumulated. The continental circulation increased the possibility for the biomass burning plumes to reach the convective regions located further north. As a consequence, biomass burning plumes were found in the upper troposphere over the Gulf of Guinea during the AEJ-S break phase. Observational evidences from the ozonesounding network at Cotonou and the carbon monoxide measured by MOPITT confirmed the alternation of the AEJ-S phases with low ozone and CO in the mid-troposphere over the Gulf of Guinea during the break phase.
Petersen, A. K., T. Warneke, M. G. Lawrence, J. Notholt, and O. Schrems (2008), First ground-based FTIR observations of the seasonal variation of carbon monoxide in the tropics, Geophysical Research Letters, 35, 3813, doi:10.1029/2007GL031393.
We present the first ground-based solar absorption Fourier Transform Infrared (FTIR) spectrometric measurements in the inner tropics over several years. The FTIR observations agree well with satellite data from the MOPITT instrument. MATCH-MPIC model simulations reproduce the mean vertical structure of the FTIR observations. The model is generally not able to reproduce the extreme enhancements seen during the specific biomass burning events by both observation instruments. Nevertheless, the model indicates that beyond the background source of CO from methane oxidation, the main contributions to the CO mixing ratios are the episodic convective injection of NMHCs and CO from South American biomass burning into the upper troposphere, along with long range transport of African biomass burning CO, particularly during spring. In future studies with more extensive observed time series, observations such as these will be valuable for evaluating ongoing improvements in global chemistry transport models.
Senten, C., M. De Mazière, B. Dils, C. Hermans, M. Kruglanski, E. Neefs, F. Scolas, A. C. Vandaele, G. Vanhaelewyn, C. Vigouroux, M. Carleer, P. F. Coheur, S. Fally, B. Barret, J. L. Baray, R. Delmas, J. Leveau, J. M. Metzger, E. Mahieu, C. Boone, K. A. Walker, P. F. Bernath, and K. Strong (2008), Technical Note: New ground-based FTIR measurements at Ile de La Réunion: observations, error analysis, and comparisons with independent data, Atmos. Chem. Phys., 8(13), 3483–3508, doi:10.5194/acp-8-3483-2008.
Ground-based high spectral resolution Fourier-transform infrared (FTIR) solar absorption spectroscopy is a powerful remote sensing technique to obtain information on the total column abundances and on the vertical distribution of various constituents in the atmosphere. This work presents results from two FTIR measurement campaigns in 2002 and 2004, held at Ile de La Réunion (21° S, 55° E). These campaigns represent the first FTIR observations carried out at a southern (sub)tropical site. They serve the initiation of regular, long-term FTIR monitoring at this site in the near future. To demonstrate the capabilities of the FTIR measurements at this location for tropospheric and stratospheric monitoring, a detailed report is given on the retrieval strategy, information content and corresponding full error budget evaluation for ozone (O3), methane (CH4), nitrous oxide (N2O), carbon monoxide (CO), ethane (C2H6), hydrogen chloride (HCl), hydrogen fluoride (HF) and nitric acid (HNO3) total and partial column retrievals. Moreover, we have made a thorough comparison of the capabilities at sea level altitude (St.-Denis) and at 2200 m a.s.l. (Maïdo). It is proved that the performances of the technique are such that the atmospheric variability can be observed, at both locations and in distinct altitude layers. Comparisons with literature and with correlative data from ozone sonde and satellite (i.e., ACE-FTS, HALOE and MOPITT) measurements are given to confirm the results. Despite the short time series available at present, we have been able to detect the seasonal variation of CO in the biomass burning season, as well as the impact of particular biomass burning events in Africa and Madagascar on the atmospheric composition above Ile de La Réunion. We also show that differential measurements between St.-Denis and Maïdo provide useful information about the concentrations in the boundary layer.
Sitnov, S. A. (2008), Analysis of the quasi-biennial variability of carbon monoxide total column, Izv. Atmos. Ocean. Phys., 44(4), 459–466, doi:10.1134/S0001433808040063.
On the basis of satellite observations of column carbon monoxide (CO) and total ozone (TO), an analysis has been performed of the connection of the interannual variability of CO with the quasi-biennial oscillation (QBO) of the equatorial stratospheric wind and the QBO of total ozone. It is found that the CO total colomn over most of the globe in the westerly phase of the QBO is greater than that in the easterly phase. The global distribution of the CO QBO amplitudes exhibits a local maximum over Indonesia, where the peak-to-peak amplitude of the CO QBO signal averages 15% of the local annual mean CO in this region. Analysis shows that the QBOs of CO are well synchronized with the QBO of wind at 50 hPa. At the same time, a joint analysis of the characteristics of the CO QBO and TO QBO demonstrates no direct photochemical coupling between of the quasi-biennial variations of TO and CO.
Tanimoto, H., Y. Sawa, S. Yonemura, K. Yumimoto, H. Matsueda, I. Uno, T. Hayasaka, H. Mukai, Y. Tohjima, K. Tsuboi, and L. Zhang (2008), Diagnosing recent CO emissions and ozone evolution in East Asia using coordinated surface observations, adjoint inverse modeling, and MOPITT satellite data, Atmos. Chem. Phys., 8(14), 3867–3880, doi:10.5194/acp-8-3867-2008.
Simultaneous ground-based measurements of ozone (O3) and carbon monoxide (CO) were conducted in March 2005 as part of the East Asian Regional Experiment (EAREX) 2005 under the umbrella of the Atmospheric Brown Clouds (ABC) project. Multiple air quality monitoring networks were integrated by performing intercomparison of individual calibration standards and measurement techniques to ensure comparability of ambient measurements, along with providing consistently high time-resolution measurements of O3 and CO at the surface sites in East Asia. Ambient data collected from eight surface stations were compared with simulation results obtained by a regional chemistry transport model to infer recent changes in CO emissions from East Asia. Our inverse estimates of the CO emissions from China up to 2005 suggested an increase of 16% since 2001, in good agreement with the recent MOPITT satellite observations and the bottom-up estimates up to 2006. The O3 enhancement relative to CO in continental pollution plumes traversed in the boundary layer were examined as a function of transport time from the Asian continent to the western Pacific Ocean. The observed ΔO3/ΔCO ratios show increasing tendency during eastward transport events due likely to en-route photochemical O3 formation, suggesting that East Asia is an important O3 source region during spring.
Turquety, S., C. Clerbaux, K. Law, P.-F. Coheur, A. Cozic, S. Szopa, D. A. Hauglustaine, J. Hadji-Lazaro, A. M. S. Gloudemans, H. Schrijver, C. D. Boone, P. F. Bernath, and D. P. Edwards (2008), CO emission and export from Asia: an analysis combining complementary satellite measurements (MOPITT, SCIAMACHY and ACE-FTS) with global modeling, Atmos. Chem. Phys., 8(17), 5187–5204, doi:10.5194/acp-8-5187-2008.
This study presents the complementary picture of the pollution outflow provided by several satellite observations of carbon monoxide (CO), based on different observation techniques. This is illustrated by an analysis of the Asian outflow during the spring of 2005, through comparisons with simulations by the LMDz-INCA global chemistry transport model. The CO observations from the MOPITT and SCIAMACHY nadir sounders, which provide vertically integrated information with excellent horizontal sampling, and from the ACE-FTS solar occultation instrument, which has limited spatial coverage but allows the retrieval of vertical profiles, are used. Combining observations from MOPITT (mainly sensitive to the free troposphere) and SCIAMACHY (sensitive to the full column) allows a qualitative evaluation of the boundary layer CO. The model tends to underestimate this residual compared to the observations, suggesting underestimated emissions, especially in eastern Asia. However, a better understanding of the consistency and possible biases between the MOPITT and SCIAMACHY CO is necessary for a quantitative evaluation. Underestimated emissions, and possibly too low lofting and underestimated chemical production in the model, lead to an underestimate of the export to the free troposphere, as highlighted by comparisons with MOPITT and ACE-FTS. Both instruments observe large trans-Pacific transport extending from ∼20° N to ∼60° N, with high upper tropospheric CO observed by ACE-FTS above the eastern Pacific (with values of up to 300 ppbv around 50° N at 500 hPa and up to ∼200 ppbv around 30° N at 300 hPa). The low vertical and horizontal resolutions of the global model do not allow the simulation of the strong enhancements in the observed plumes. However, the transport patterns are well captured, and are mainly attributed to export from eastern Asia, with increasing contributions from South Asia and Indonesia towards the tropics. Additional measurements of C2H2, C2H6 and HCN by ACE-FTS provide further information on the plume history. C2H2 and C2H6 enhancements are well correlated with the CO plumes, indicating common sources and rapid trans-Pacific transport. HCN observations show that the biomass burning contributes mainly at latitudes lower than ∼40° N. This study provides a first step towards a full combination of complementary observations, but also highlights the need for a better evaluation of consistency between the datasets in order to allow precise quantitative analyses.
Yurganov, L. N., W. W. McMillan, A. V. Dzhola, E. I. Grechko, N. B. Jones, and G. R. van der Werf (2008), Global AIRS and MOPITT CO measurements: Validation, comparison, and links to biomass burning variations and carbon cycle, Journal of Geophysical Research: Atmospheres, 113(D9), n/a–n/a, doi:10.1029/2007JD009229.
New results of CO global total column measurements using the Atmospheric Infrared Sounder (AIRS) aboard the Aqua satellite in comparison with Measurements of Pollution in the Troposphere (MOPITT) sensor aboard the Terra satellite are presented. Both data sets are validated using ground-based total column measurements in Russia and Australia. A quality parameter based on the Profile Percent A Priori values from the standard MOPITT product is introduced. AIRS data (version 4) for biomass burning events are in agreement or lower than both MOPITT and ground measurements, but CO bursts can be seen by AIRS in most cases. For the cases of low CO amounts in the Southern Hemisphere AIRS has a positive bias of ∼30–40% compared to MOPITT and ground truth. MOPITT data were used to estimate interannual variations of CO sources assuming a standard seasonal cycle for the main CO remover OH. A positive trend of CO global emissions for the second half of the year between 2000 and 2006 was found with no visible trend for the first half of the year. CO annual emission in 2006 was 184 ± 40 Tg higher that that in 2000–2001. The monthly emission anomalies correlate well with an independently calculated Global Fire Emission Database (GFED2). Total carbon contribution from biomass burning in 1997, 1998 (both estimated by GFED2), and 2006 (according to MOPITT) were as high as (0.6–1) Pg C/year larger than in 2000, suggesting that fires can explain a substantial fraction of the interannual variability of CO2.

2007

Arellano, A. F., K. Raeder, J. L. Anderson, P. G. Hess, L. K. Emmons, D. P. Edwards, G. G. Pfister, T. L. Campos, and G. W. Sachse (2007), Evaluating model performance of an ensemble-based chemical data assimilation system during INTEX-B field mission, Atmos. Chem. Phys., 7(21), 5695–5710, doi:10.5194/acp-7-5695-2007.
We present a global chemical data assimilation system using a global atmosphere model, the Community Atmosphere Model (CAM3) with simplified chemistry and the Data Assimilation Research Testbed (DART) assimilation package. DART is a community software facility for assimilation studies using the ensemble Kalman filter approach. Here, we apply the assimilation system to constrain global tropospheric carbon monoxide (CO) by assimilating meteorological observations of temperature and horizontal wind velocity and satellite CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument. We verify the system performance using independent CO observations taken on board the NSF/NCAR C-130 and NASA DC-8 aircrafts during the April 2006 part of the Intercontinental Chemical Transport Experiment (INTEX-B). Our evaluations show that MOPITT data assimilation provides significant improvements in terms of capturing the observed CO variability relative to no MOPITT assimilation (i.e. the correlation improves from 0.62 to 0.71, significant at 99% confidence). The assimilation provides evidence of median CO loading of about 150 ppbv at 700 hPa over the NE Pacific during April 2006. This is marginally higher than the modeled CO with no MOPITT assimilation (∼140 ppbv). Our ensemble-based estimates of model uncertainty also show model overprediction over the source region (i.e. China) and underprediction over the NE Pacific, suggesting model errors that cannot be readily explained by emissions alone. These results have important implications for improving regional chemical forecasts and for inverse modeling of CO sources and further demonstrate the utility of the assimilation system in comparing non-coincident measurements, e.g. comparing satellite retrievals of CO with in-situ aircraft measurements.
Bhattacharjee, P. S., A. K. Prasad, M. Kafatos, and R. P. Singh (2007), Influence of a dust storm on carbon monoxide and water vapor over the Indo-Gangetic Plains, Journal of Geophysical Research: Atmospheres, 112(D18), n/a–n/a, doi:10.1029/2007JD008469.
Dust storms are meteorological phenomena that produce air quality hazards over specific regions lasting from a few hours to many days. They are common in the western part of India during the months of April–June, particularly over Delhi and the surrounding Indo-Gangetic (IG) plains. In this paper, a dust storm event over Delhi, Kanpur and Varanasi during 1–11 April 2005 was used to study the vertical changes in the atmosphere. We studied data from the Measurement of Pollution in the Atmosphere (MOPITT) instrument onboard the Terra satellite, daytime vertical carbon monoxide (CO) mixing ratio and the Atmospheric Infra-red Sounder (AIRS) onboard the Aqua satellite water vapor mass mixing ratio associated with dust storm over three locations in the IG plains. Evidence of vertical transport of CO to upper troposphere (UT) is observed from stability indices derived from radiosonde data, NCEP reanalysis wind and HYSPLIT model over Delhi. The strong upward convection during dust storms reduces CO in the lower troposphere and increases CO at around 350 hPa pressure level. Water vapor mass mixing ratio shows an increase at 700–850 hPa pressure level during the dust storm event over all locations. The changes of water vapor mass mixing ratio and CO during the dust storm are found to be more pronounced over Delhi and Kanpur while they are comparatively less over Varanasi, due to low intensity during transport of dust from west to east in the IG plains. The increased concentration of CO and water vapor mass mixing ratio at different pressure levels 350 hPa and 700–850 hPa respectively with corresponding decrease in surface concentration (at pressure level 700–1000 hPa and 925–1000 hPa respectively) have been investigated during a major dust storm period. The changes in CO and water vapor mass mixing ratio are found to be consistent with the observed changes in vertical stability of the atmosphere.
Bian, H., M. Chin, S. R. Kawa, B. Duncan, A. Arellano, and P. Kasibhatla (2007), Sensitivity of global CO simulations to uncertainties in biomass burning sources, Journal of Geophysical Research: Atmospheres, 112(D23), n/a–n/a, doi:10.1029/2006JD008376.
One of the largest uncertainties for the modeling of tropospheric carbon monoxide (CO) concentration is the timing, location, and magnitude of biomass burning emissions. We investigate the sensitivity of simulated CO in the Unified Chemistry Transport Model (UCTM) to several biomass burning emissions, including four bottom-up and two top-down inventories. We compare the sensitivity experiments with observations from MOPITT, surface and airborne NOAA Global Monitoring Division network data, and the TRACE-P field campaign. The variation of the global annual emissions of these six biomass burning inventories is within 30%; however, their regional variations are often much higher (factor of 2–5). These uncertainties translate to about 6% variation in the global simulated CO but more than a 100% variation in some regions. The annual mean CO variation is greater in the Southern Hemisphere (>12%) than in the Northern Hemisphere (<5%), largely because biomass burning is a higher percentage of the total source in the Southern Hemisphere. Comparisons with CO observations indicate that each model inventory has its strengths and shortcomings, and these regional variations are examined. Overall the model CO concentrations are within the observed range of variability at most stations including Ascension Island, which is strongly influenced by fire emissions. In addition, we discuss the systematic biases that exist in the inventories developed by the similar methodologies and original satellite data.
Bousserez, N., J. L. Attié, V. H. Peuch, M. Michou, G. Pfister, D. Edwards, L. Emmons, C. Mari, B. Barret, S. R. Arnold, A. Heckel, A. Richter, H. Schlager, A. Lewis, M. Avery, G. Sachse, E. V. Browell, and J. W. Hair (2007), Evaluation of the MOCAGE chemistry transport model during the ICARTT/ITOP experiment, Journal of Geophysical Research: Atmospheres, 112(D10), n/a–n/a, doi:10.1029/2006JD007595.
Intercontinental Transport of Ozone and Precursors (ITOP), part of International Consortium for Atmospheric Research on Transport and Transformation (ICARTT), was a large experimental campaign designed to improve our understanding of the chemical transformations within plumes during long-range transport (LRT) of pollution from North America to Europe. This campaign took place in July and August 2004, when a strong fire season occurred in North America. Burning by-products were transported over large distances, sometimes reaching Europe. A chemical transport model, Modélisation de la Chimie Atmosphérique Grande Echelle (MOCAGE), with a high grid resolution (0.5° × 0.5°) over the North Atlantic area and a daily inventory of biomass burning emissions over the United States, has been used to simulate the period. By comparing our results with available aircraft in situ measurements and satellite data (MOPITT CO and SCIAMACHY NO2), we show that MOCAGE is capable of representing the main characteristics of the tropospheric ozone-NOx-hydrocarbon chemistry during the ITOP experiment. In particular, high resolution allows the accurate representation of the pathway of exported pollution over the Atlantic, where plumes were transported preferentially at 6 km altitude. The model overestimates OH mixing ratios up to a factor of 2 in the lower troposphere, which results in a global overestimation of hydrocarbons oxidation by-products (PAN and ketones) and an excess of O3 (30–50 ppbv) in the planetary boundary layer (PBL) over the continental United States. Sensitivity study revealed that lightning NO emissions contributed significantly to the NOx budget in the upper troposphere of northeast America during the summer 2004.
Buchwitz, M., I. Khlystova, H. Bovensmann, and J. P. Burrows (2007), Three years of global carbon monoxide from SCIAMACHY: comparison with MOPITT and first results related to the detection of enhanced CO over cities, Atmos. Chem. Phys., 7(9), 2399–2411, doi:10.5194/acp-7-2399-2007.
Carbon monoxide (CO) is an important atmospheric constituent affecting air quality and climate. SCIAMACHY on ENVISAT is currently the only satellite instrument that can measure the vertical column of CO with nearly equal sensitivity at all altitudes down to the Earth’s surface because of its near-infrared nadir observations of reflected solar radiation. Here we present three years’ (2003-2005) of SCIAMACHY CO columns consistently retrieved with the latest version of our retrieval algorithm (WFMDv0.6). We describe the retrieval method and discuss the multi-year global CO data set focusing on a comparison with the operational CO column data product of MOPITT. We found reasonable to good agreement (∼20%) with MOPITT, with the best agreement for 2004. We present detailed results for various regions (Europe, Middle East, India, China) and discuss to what extent enhanced levels of CO can be detected over populated areas including individual cities. The expected CO signal from cities is close to or even below the detection limit of individual measurements. We show that cities can be identified when averaging long time series.
Cook, P. A., N. H. Savage, S. Turquety, G. D. Carver, F. M. O’Connor, A. Heckel, D. Stewart, L. K. Whalley, A. E. Parker, H. Schlager, H. B. Singh, M. A. Avery, G. W. Sachse, W. Brune, A. Richter, J. P. Burrows, R. Purvis, A. C. Lewis, C. E. Reeves, P. S. Monks, J. G. Levine, and J. A. Pyle (2007), Forest fire plumes over the North Atlantic: p-TOMCAT model simulations with aircraft and satellite measurements from the ITOP/ICARTT campaign, Journal of Geophysical Research: Atmospheres, 112(D10), n/a–n/a, doi:10.1029/2006JD007563.
Intercontinental Transport of Ozone and Precursors (ITOP) (part of International Consortium for Atmospheric Research on Transport and Transformation (ICARTT)) was an intense research effort to measure long-range transport of pollution across the North Atlantic and its impact on O3 production. During the aircraft campaign plumes were encountered containing large concentrations of CO plus other tracers and aerosols from forest fires in Alaska and Canada. A chemical transport model, p-TOMCAT, and new biomass burning emissions inventories are used to study the emissions long-range transport and their impact on the troposphere O3 budget. The fire plume structure is modeled well over long distances until it encounters convection over Europe. The CO values within the simulated plumes closely match aircraft measurements near North America and over the Atlantic and have good agreement with MOPITT CO data. O3 and NOx values were initially too great in the model plumes. However, by including additional vertical mixing of O3 above the fires, and using a lower NO2/CO emission ratio (0.008) for boreal fires, O3 concentrations are reduced closer to aircraft measurements, with NO2 closer to SCIAMACHY data. Too little PAN is produced within the simulated plumes, and our VOC scheme’s simplicity may be another reason for O3 and NOx model-data discrepancies. In the p-TOMCAT simulations the fire emissions lead to increased tropospheric O3 over North America, the north Atlantic and western Europe from photochemical production and transport. The increased O3 over the Northern Hemisphere in the simulations reaches a peak in July 2004 in the range 2.0 to 6.2 Tg over a baseline of about 150 Tg.
Deeter, M. N., D. P. Edwards, and J. C. Gille (2007a), Retrievals of carbon monoxide profiles from MOPITT observations using lognormal a priori statistics, Journal of Geophysical Research: Atmospheres, 112(D11), n/a–n/a, doi:10.1029/2006JD007999.
Optimal estimation methods, such as the “maximum a posteriori” solution, are commonly employed for retrieving profiles of atmospheric trace gases from satellite observations. To complement the information actually contained in the measured radiances, such methods exploit a priori information describing the gases’ variability characteristics. We show that in situ surface-based data sets for carbon monoxide (CO) volume mixing ratio (VMR) indicate that the variability of CO is more accurately modeled in terms of a “lognormal” probability distribution function (PDF) than a “VMR-normal” PDF. The VMR-normal PDF is particularly poor at describing CO variability in unpolluted conditions. We also compare retrievals of carbon monoxide (CO) vertical profiles based on Measurements of Pollution in the Troposphere (MOPITT) observations for 1 day using both VMR-normal and lognormal statistical models. Use of the lognormal model improves retrieval convergence and yields fewer profiles with unphysically small VMR values. Generally, these results highlight the importance of properly representing the variability of trace gas concentrations in optimal estimation-based retrieval algorithms.
Deeter, M. N., D. P. Edwards, J. C. Gille, and J. R. Drummond (2007b), Sensitivity of MOPITT observations to carbon monoxide in the lower troposphere, Journal of Geophysical Research (Atmospheres), 112(d11), 24306, doi:10.1029/2007JD008929.
The sensitivity of Measurements of Pollution in the Troposphere (MOPITT) observations to carbon monoxide (CO) concentrations in the lower troposphere (LT) varies widely as the result of variability in thermal contrast conditions. This effect is evident in both the MOPITT weighting functions and averaging kernels, particularly after these quantities are properly normalized to remove grid effects. Comparisons of simulated weighting functions and averaging kernels with operational data confirm the significance of thermal contrast effects. Retrieval sensitivity to LT CO is greatest in daytime observations over land, particularly in tropical and midlatitude regions exhibiting large diurnal variations in surface temperature. Nighttime observations over land typically exhibit poor sensitivity to LT CO. On the global scale, analysis of MOPITT averaging kernels for 1 month indicates that daytime MOPITT observations offer useful sensitivity to LT CO over large areas of most continents. Exceptions include tropical rainforests in Africa and South America, where thermal contrast conditions are relatively weak.
Emmons, L. K., G. G. Pfister, D. P. Edwards, J. C. Gille, G. Sachse, D. Blake, S. Wofsy, C. Gerbig, D. Matross, and P. Nédélec (2007), Measurements of Pollution in the Troposphere (MOPITT) validation exercises during summer 2004 field campaigns over North America, Journal of Geophysical Research: Atmospheres, 112(D12), n/a–n/a, doi:10.1029/2006JD007833.
Measurements of carbon monoxide (CO) made as part of three aircraft experiments during the summer of 2004 over North America have been used for the continued validation of the CO retrievals from the Measurements of Pollution in the Troposphere (MOPITT) instrument on board the Terra satellite. Vertical profiles measured during the NASA INTEX-A campaign, designed to be coincident with MOPITT overpasses, as well as measurements made during the COBRA-2004 and MOZAIC experiments, provided valuable validation comparisons. On average, the MOPITT CO retrievals are biased slightly high for these North America locations. While the mean bias differs between the different aircraft experiments (e.g., 7.0 ppbv for MOZAIC to 18.4 ppbv for COBRA at 700 hPa), the standard deviations are quite large, so the results for the three data sets can be considered consistent. On average, it is estimated that MOPITT is 7–14% high at 700 hPa and ∼3% high at 350 hPa. These results are consistent with the validation results for the Carr, Colorado, Harvard Forest, Massachusetts, and Poker Flats, Alaska, aircraft profiles for “phase 2” presented by Emmons et al. (2004) and are generally within the design criteria of 10% accuracy.
Generoso, S., I. Bey, J.-L. Attié, and F.-M. Bréon (2007), A satellite- and model-based assessment of the 2003 Russian fires: Impact on the Arctic region, Journal of Geophysical Research: Atmospheres, 112(D15), n/a–n/a, doi:10.1029/2006JD008344.
In this paper, we address the issues of the representation of boreal fires in a global chemistry and transport model (GEOS-Chem) as well as their contribution to the Arctic aerosol optical thickness and black carbon (BC) deposition, with a focus on the 2003 Russian fires. We use satellite observations from the MOPITT, POLDER and MODIS sensors to evaluate the model performances in simulating the fire pollution export over the North Pacific. Our results show that aerosol and carbon monoxide (CO) outflow is best reproduced in our model when fire emissions are (1) increased to 72 Tg for CO, 0.5 Tg C for BC, and 5.3 Tg C for organic carbon over the entire fire season; (2) prescribed on a daily basis; and (3) injected up to 4.5 km in July and August. The use of daily, rather than monthly, biomass burning emission inventories improves significantly the representation of the aerosol outflow, but has little impact on CO. The injection of fire emissions above the boundary layer influences both the CO and aerosol columns but only during the late fire season. The model improvements with respect to the standard configuration induce an increase of a factor up to 2 on the aerosol optical thickness and the mass of BC deposited in the Northern Hemisphere. According to our improved simulation, the 2003 Russian fires contributed to 16–33% of the aerosol optical thickness and to 40–56% of the mass of BC deposited, north of 75°N in spring and summer. They contribute to the aerosol optical thickness by more than 30% during the days of Arctic haze events in spring and summer.
Glatthor, N., T. von Clarmann, H. Fischer, B. Funke, U. Grabowski, M. Höpfner, S. Kellmann, M. Kiefer, A. Linden, M. Milz, T. Steck, and G. P. Stiller (2007), Global peroxyacetyl nitrate (PAN) retrieval in the upper troposphere from limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS), Atmos. Chem. Phys., 7(11), 2775–2787, doi:10.5194/acp-7-2775-2007.
We use limb emission spectra of the Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) onboard the ENVIronmental SATellite (ENVISAT) to derive the first global distribution of peroxyacetyl nitrate (PAN) in the upper troposphere. PAN is generated in tropospheric air masses polluted by fuel combustion or biomass burning and acts as a reservoir and carrier of NOx in the cold free troposphere. PAN exhibits continuum-like broadband structures in the mid-infrared region and was retrieved in a contiguous analysis window covering the wavenumber region 775-800 cm-1. The interfering species CCl4, HCFC-22, H2O, ClONO2, CH3CCl3 and C2H2 were fitted along with PAN, whereas pre-fitted profiles were used to model the contribution of other contaminants like ozone. Sensitivity tests consisting in retrieval without consideration of PAN demonstrated the existence of PAN signatures in MIPAS spectra obtained in polluted air masses. The analysed dataset consists of 10 days between 4 October and 1 December 2003. This period covers the end of the biomass burning season in South America and South and East Africa, in which generally large amounts of pollutants are produced and distributed over wide areas of the southern hemispheric free troposphere. Indeed, elevated PAN amounts of 200-700 pptv were measured in a large plume extending from Brasil over the Southern Atlantic, Central and South Africa, the South Indian Ocean as far as Australia at altitudes between 8 and 16 km. Enhanced PAN values were also found in a much more restricted area between northern subtropical Africa and India. The most significant northern midlatitude PAN signal was detected in an area at 8 km altitude extending from China into the Chinese Sea. The average mid and high latitude PAN amounts found at 8 km were around 125 pptv in the northern, but only between 50 and 75 pptv in the southern hemisphere. The PAN distribution found in the southern hemispheric tropics and subtropics is highly correlated with the jointly fitted acetylene (C2H2), which is another pollutant produced by biomass burning, and agrees reasonably well with the CO plume detected during end of September 2003 at the 275 hPa level (∼10 km) by the Measurement of Pollution in the Troposphere (MOPITT) instrument on the Terra satellite. Similar southern hemispheric PAN amounts were also observed by previous airborne measurements performed in September/October 1992 and 1996 above the South Atlantic and the South Pacific, respectively.
Huntrieser, H., H. Schlager, A. Roiger, M. Lichtenstern, U. Schumann, C. Kurz, D. Brunner, C. Schwierz, A. Richter, and A. Stohl (2007), Lightning-produced NOx over Brazil during TROCCINOX: airborne measurements in tropical and subtropical thunderstorms and the  importance of mesoscale convective systems, Atmos. Chem. Phys., 7(11), 2987–3013, doi:10.5194/acp-7-2987-2007.
During the TROCCINOX field experiments in February-March 2004 and February 2005, airborne in situ measurements of NO, NOy, CO, and O3 mixing ratios and the J(NO2) photolysis rate were carried out in the anvil outflow of thunderstorms over southern Brazil. Both tropical and subtropical thunderstorms were investigated, depending on the location of the South Atlantic convergence zone. Tropical air masses were discriminated from subtropical ones according to the higher equivalent potential temperature (Θe) in the lower and mid troposphere, the higher CO mixing ratio in the mid troposphere, and the lower wind velocity in the upper troposphere within the Bolivian High (north of the subtropical jet stream). During thunderstorm anvil penetrations, typically at 20-40 km horizontal scales, NOx mixing ratios were distinctly enhanced and the absolute mixing ratios varied between 0.2-1.6 nmol mol-1 on average. This enhancement was mainly attributed to NOx production by lightning and partly due to upward transport from the NOx-richer boundary layer. In addition, CO mixing ratios were occasionally enhanced, indicating upward transport from the boundary layer. For the first time, the composition of the anvil outflow from a large, long-lived mesoscale convective system (MCS) advected from northern Argentina and Uruguay was investigated in more detail. Over a horizontal scale of about 400 km, NOx, CO and O3 absolute mixing ratios were significantly enhanced in these air masses in the range of 0.6-1.1, 110-140 and 60-70 nmol mol-1, respectively. Analyses from trace gas correlations and a Lagrangian particle dispersion model indicate that polluted air masses, probably from the Buenos Aires urban area and from biomass burning regions, were uplifted by the MCS. Ozone was distinctly enhanced in the aged MCS outflow, due to photochemical production and entrainment of O3-rich air masses from the upper troposphere - lower stratosphere region. The aged MCS outflow was transported to the north, ascended and circulated, driven by the Bolivian High over the Amazon basin. In the observed case, the O3-rich MCS outflow remained over the continent and did not contribute to the South Atlantic ozone maximum.
Hyer, E. J., E. S. Kasischke, and D. J. Allen (2007a), Effects of source temporal resolution on transport simulations of boreal fire emissions, Journal of Geophysical Research: Atmospheres, 112(D1), n/a–n/a, doi:10.1029/2006JD007234.
The quality of temporal information from daily burned area inputs was evaluated using a transport and chemistry experiment. Carbon monoxide emissions from boreal forest fires were estimated using burned area inputs with daily resolution. Averaging of emissions data to create 30-day aggregate data reduced the variance by 80%, indicating a substantial loss of information. Data from Russia, Canada, and Alaska were tested for periodicity to uncover systematic gaps in daily data. Some evidence of periodicity was found in data from Alaska, where temporal information came from fire mapping by the Alaskan Fire Service. Autocorrelation decayed rapidly and nearly monotonically for Canada and Russia, where temporal information came from Advanced Very High Resolution Radiometer (AVHRR) satellite observations. Daily data as well as 7-day and 30-day aggregates were used as input to the University of Maryland Atmospheric Chemistry and Transport Model, and output was compared with CO observations from the Cooperative Air Sampling Network (CASN); continuous measurements from Mace Head, Ireland; and total column CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) instrument. CASN flask measurements showed no sensitivity to high-frequency variability in the source, indicating the effectiveness of the filtering protocol at ensuring only well-mixed air masses are sampled in this data set. Differences between daily and 7-day simulations were too small for quantitative comparison in any of the data. For cases where the differences were substantial, simulations using daily and 7-day average sources agreed better with observations than 30-day average sources.
Hyer, E. J., D. J. Allen, and E. S. Kasischke (2007b), Examining injection properties of boreal forest fires using surface and satellite measurements of CO transport, Journal of Geophysical Research: Atmospheres, 112(D18), n/a–n/a, doi:10.1029/2006JD008232.
Boreal forest fires are highly variable in space and time and also have variable vertical injection properties. We compared a University of Maryland Chemistry and Transport Model (UMD-CTM) simulation of boreal forest fire CO in the summer of 2000 to surface observations from the NOAA Cooperative Air Sampling Network and satellite observations of CO from the Measurement of Pollutants in the Troposphere (MOPITT) instrument to investigate the sensitivity of these measurements to injection height and to evaluate the bulk injection properties of the boreal fire source. Our results show that emissions at the surface produce more than twice the signal in surface CO measurements compared with emissions injected into the upper troposphere. Surface injection yielded the best agreement with surface observations, but high-altitude injection resulted in very small variations at the surface, and so the statistical comparison with surface observations was inconclusive. Because of the vertical sensitivity of MOPITT, estimated total CO burden north of 30°N was 10% higher for upper tropospheric injection of boreal forest fire CO compared to surface release. We used a contrast filter to select the MOPITT retrievals most sensitive to boreal forest fire injection height and found that the best agreement between simulation results and MOPITT observations was obtained with midtropospheric injection of emissions and with pressure-weighted distribution of emissions through the tropospheric column. Appendix A uses CTM output to examine quantitatively the bias and errors in calculations of total column CO and total CO burden using MOPITT CO retrievals.
I-I Lin, J.-P. Chen, G. T. F. Wong, C.-W. Huang, and C.-C. Lien (2007), Aerosol input to the South China Sea: Results from the MODerate Resolution Imaging Spectro-radiometer, the Quick Scatterometer, and the Measurements of Pollution in the Troposphere Sensor, Deep Sea Research Part II: Topical Studies in Oceanography, 54(14–15), 1589–1601, doi:10.1016/j.dsr2.2007.05.013.
Data from the MODerate Resolution Imaging Spectro-radiometer (MODIS) and other satellite sensors in 2002–2004 indicate that, in addition to locally produced sea-salt particles, aerosols from various remote sources also find their ways to the South China Sea, including industrial/urban pollution in eastern China, wind-blown dust from Asian deserts and biomass burning in Sumatra and Borneo. Among these sources, anthropogenic aerosols from eastern China are produced year round while desert dusts are produced primarily between February and April and biomass burning smoke from August to October. In terms of size of aerosols, sea salt and dust predominate the coarse mode while pollution and smoke predominate the fine-mode particles. Our study suggests that the aerosol input to the South China Sea come from different remote sources dependent upon the season, as opposed to a single dust source as previously anticipated. In the winter monsoon season from November to April, the prevailing northeasterly carries anthropogenic aerosols mixed with dust during dust outbreaks to the northern South China Sea. In the summer monsoon season from June to September, the prevailing southwesterly favours the transporting of smoke particles associated with biomass burning in Borneo and Sumatra to the southern South China Sea. The variety of remote aerosol sources associated with strong spatial and temporal variability of transporting aerosols to the region shows the complexity of atmospheric impact on the biogeochemistry in the South China Sea. Hence, an integrated research approach is deemed critical to assess the biogeochemical impact of these aerosols to the South China Sea.
Ito, A., A. Ito, and H. Akimoto (2007), Seasonal and interannual variations in CO and BC emissions from open biomass burning in Southern Africa during 1998–2005, Global Biogeochemical Cycles, 21(2), n/a–n/a, doi:10.1029/2006GB002848.
We estimate the emissions of carbon monoxide (CO) and black carbon (BC) from open vegetation fires in the Southern Hemisphere Africa from 1998 to 2005 using satellite information in conjunction with a biogeochemical model. Monthly burned areas at a 0.5-degree resolution are estimated from the Visible InfraRed Scanner (VIRS) fire count product and the MODerate resolution Imaging Spectroradiometer (MODIS) burned area data set associated with the MODIS tree cover imagery in grasslands and woodlands. The monthly fuel load distributions are derived from a 0.5-degree terrestrial carbon cycle model in conjunction with satellite data. The monthly maps of combustion factors and emission factors are estimated using empirical models that predict the effects of fuel conditions on these factors in grasslands and woodlands. Our annually averaged effective CO and BC emissions per area burned are 27 g CO m−2 and 0.17 g BC m−2 which are consistent with the products of fuel consumption and emission factors typically measured in southern Africa. The CO and BC emissions from open vegetation burning in southern Africa range from 45 Tg CO yr−1 and 0.26 Tg BC yr−1 for 2002 to 75 Tg CO yr−1 and 0.42 Tg BC yr−1 for 1998. The monthly averaged burned areas from VIRS fire counts peak earlier than modeled CO emissions. This characteristic delay between burned areas and emissions is mainly explained by significant changes in combustion factors for woodlands in our model. Consequently, the peaks in CO and BC emissions from our bottom-up approach are identical to those from previous top-down estimates using the Measurement Of the Pollution In The Troposphere (MOPITT) and the Total Ozone Mapping Spectrometer (TOMS) Aerosol Index (AI) data.
Jones, T. A., and S. A. Christopher (2007), MODIS derived fine mode fraction characteristics of marine, dust, and anthropogenic aerosols over the ocean, constrained by GOCART, MOPITT, and TOMS, Journal of Geophysical Research: Atmospheres, 112(D22), n/a–n/a, doi:10.1029/2007JD008974.
One year (December 2003 to November 2004) of Terra Moderate Resolution Imaging Spectroradiometer (MODIS), Total Ozone Mapping Spectrometer (TOMS), and Measurement of Pollution in the Troposphere (MOPITT) data over the open ocean are used in conjunction with the Goddard Chemistry Transport Model (GOCART) to characterize differing aerosol types as a function of satellite observable parameters. GOCART model output is used to select regions that are dominated (at least 80% of the total aerosol optical thickness from a single aerosol species) by anthropogenic (black carbon + organic carbon + sulfate), dust (DU) and sea salt regions (SS). Aerosol optical thickness (AOT) and fine mode fraction (FMF) retrieved from MODIS are averaged for each aerosol species region at 1 month intervals to examine the observational differences among each aerosol species. Anthropogenic (AN) aerosols are further separated into those produced primarily from biomass burning (BB) versus those from combustion and industrial pollution (PO). TOMS ultraviolet absorbing aerosol index (AI) in conjunction with MOPITT carbon monoxide (CO) data sets on Terra are used to contrast the differences between BB and PO aerosol properties. Annually averaged estimates for SS, DU, and AN MODIS FMF are 0.25 ± 0.07, 0.45 ± 0.05, and 0.84 ± 0.04, respectively, in agreement with or slightly lower than previous estimates. However, FMF values were observed to change substantially as a function of space and time as regions dominated by single aerosol types shrink, expand, and move around from month to month. The greatest variability in FMF was observed for SS and DU aerosols. SS are associated with regions of high near-surface wind speeds in the Southern Hemisphere, which have large temporal and spatial variations. Dust transport off of the Saharan Desert is maximized in the Northern Hemisphere summer, increasing the area of predominately dust aerosols. MODIS aerosol effective radius for each aerosol type also showed a similar trend with SS, DU, and AN values of 1.03, 0.68, and 0.32 μm. TOMS-AI values for DU exceeded SS and AN values up to 100% between April and October 2004 in association with the greatest dust concentrations in the North Atlantic. For BB and PO components of AN aerosols, no significant difference in MODIS FMF were observed; however, substantial differences in TOMS-AI and MOPITT values were observed between BB and PO aerosols, especially between June and November. For both TOMS-AI and MOPITT CO, BB aerosols are generally associated with higher values than are PO aerosols. The use of GOCART to constrain regions where a dominant aerosol species exists has allowed a comprehensive analysis of the satellite observed properties of various aerosol species.
Kampe, T. U., and I. N. Sokolik (2007), Remote sensing retrievals of fine mode aerosol optical depth and impacts on its correlation with CO from biomass burning, Geophysical Research Letters, 34(12), n/a–n/a, doi:10.1029/2007GL029805.
It has been suggested that simultaneous satellite measurements of mid-visible fine mode aerosol optical depth τf and CO concentrations can aid in improving the characterization of biomass burning in chemical transport models. However different approaches for retrieving τf have recently been proposed. Using MODIS and MOPITT data, we examine the impact these have on the regression slope between enhancements of τf and CO (Δτf/ΔCO) for representative biomass burning cases, including savanna and extratropical forests. Both MODIS Collection 4 and recent Collection 5 aerosol products are used in our study. We find that τf varies systematically with retrieval method causing systematic differences in the slope of regression. Regardless of method used, noticeable differences in regression slope are observed for different types of biomass burning. Our results point out the need for consistency in defining τf between satellite measurements and models if the Δτf/ΔCO ratio is to be used as a constraint.
de Laat, A. T. J., A. M. S. Gloudemans, I. Aben, M. Krol, J. F. Meirink, G. R. van der Werf, and H. Schrijver (2007), Scanning Imaging Absorption Spectrometer for Atmospheric Chartography carbon monoxide total columns: Statistical evaluation and comparison with chemistry transport model results, Journal of Geophysical Research: Atmospheres, 112(D12), n/a–n/a, doi:10.1029/2006JD008256.
This paper presents a detailed statistical analysis of one year (September 2003 to August 2004) of global Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY) carbon monoxide (CO) total column retrievals from the Iterative Maximum Likelihood Method (IMLM) algorithm, version 6.3. SCIAMACHY provides the first solar reflectance measurements of CO and is uniquely sensitive down to the boundary layer. SCIAMACHY measurements and chemistry transport model (CTM) results are compared and jointly evaluated. Significant improvements in agreement occur, especially close to biomass burning emission regions, when the new Global Fire Emissions Database version 2 (GFEDv2) is used with the CTM. Globally, the seasonal variation of the model is very similar to that of the SCIAMACHY measurements. For certain locations, significant differences were found, which are likely related to modeling errors due to CO emission uncertainties. Statistical analysis shows that differences between single SCIAMACHY CO total column measurements and corresponding model results are primarily explained by random instrument noise errors. This strongly suggests that the random instrument noise errors are a good diagnostic for the precision of the measurements. The analysis also indicates that noise in single SCIAMACHY CO measurements is generally greater than actual variations in total columns. It is thus required to average SCIAMACHY data over larger temporal and spatial scales to obtain valuable information. Analyses of monthly averaged SCIAMACHY measurements over 3° × 2° geographical regions indicates that they are of sufficient accuracy to reveal valuable information about spatial and temporal variations in CO columns and provide an important tool for model validation. A large spatial and temporal variation in instrument noise errors exists which shows a close correspondence with the spatial distribution of surface albedo and cloud cover. This large spatial variability is important for the use of monthly and annual mean SCIAMACHY CO total column measurements. The smallest instrument noise errors of monthly mean 3° × 2° SCIAMACHY CO total columns measurements are 0.01 × 1018 molecules/cm2 for high surface albedo areas over the Sahara. Errors in SCIAMACHY CO total column retrievals due to errors other than instrument noise, like cloud cover, calibration, retrieval uncertainties and averaging kernels are estimated to be about 0.05–0.1 × 1018 molecules/cm2 in total. The bias found between model and observations is around 0.05–0.1 1018 molecules/cm2 (or about 5%) which also includes model errors. This thus provides a best estimate of the currently achievable measurement accuracy for SCIAMACHY CO monthly mean averages.
Liang, Q., L. Jaeglé, R. C. Hudman, S. Turquety, D. J. Jacob, M. A. Avery, E. V. Browell, G. W. Sachse, D. R. Blake, W. Brune, X. Ren, R. C. Cohen, J. E. Dibb, A. Fried, H. Fuelberg, M. Porter, B. G. Heikes, G. Huey, H. B. Singh, and P. O. Wennberg (2007), Summertime influence of Asian pollution in the free troposphere over North America, Journal of Geophysical Research: Atmospheres, 112(D12), n/a–n/a, doi:10.1029/2006JD007919.
We analyze aircraft observations obtained during INTEX-A (1 July to 14 August 2004) to examine the summertime influence of Asian pollution in the free troposphere over North America. By applying correlation analysis and principal component analysis (PCA) to the observations between 6 and 12 km, we find dominant influences from recent convection and lightning (13% of observations), Asia (7%), the lower stratosphere (7%), and boreal forest fires (2%), with the remaining 71% assigned to background. Asian air masses are marked by high levels of CO, O3, HCN, PAN, C2H2, C6H6, methanol, and SO42–. The partitioning of NOy species in the Asian plumes is dominated by PAN (∼600 pptv), with varying NOx/HNO3 ratios in individual plumes, consistent with individual transit times of 3–9 days. Export of Asian pollution occurred in warm conveyor belts of midlatitude cyclones, deep convection, and in typhoons. Compared to Asian outflow measurements during spring, INTEX-A observations display lower levels of anthropogenic pollutants (CO, C3H8, C2H6, C6H6) due to shorter summer lifetimes; higher levels of biogenic tracers (methanol and acetone) because of a more active biosphere; and higher levels of PAN, NOx, HNO3, and O3 reflecting active photochemistry, possibly enhanced by efficient NOy export and lightning. The high ΔO3/ΔCO ratio (0.76 mol/mol) in Asian plumes during INTEX-A is due to strong photochemical production and, in some cases, mixing with stratospheric air along isentropic surfaces. The GEOS-Chem global model captures the timing and location of the Asian plumes. However, it significantly underestimates the magnitude of observed enhancements in CO, O3, PAN and NOx.
Lin, Y., C. Zhao, L. Peng, and Y. Fang (2007), A new method to calculate monthly CO emissions using MOPITT satellite data, CHINESE SCI BULL, 52(18), 2551–2558, doi:10.1007/s11434-007-0349-z.
A new method is developed to calculate monthly CO emission data using MOZART modeled and MOPITT observed CO data in 2004. New CO emission data were obtained with budget analysis of the processes controlling CO concentration such as surface emission, transport, chemical transform and dry deposition. MOPITT data were used to constrain the model simulation. New CO emission data agree well with Horowitz’s emissions in the spatial distributions. Horowitz’s emissions are found to underestimate CO emissions significantly in the industrial areas of Asia and North America, where high CO emissions are mainly due to the anthropogenic activities. New CO emissions can better reflect the more recent CO actual emissions than Horowitz’s.
Luo, M., C. P. Rinsland, C. D. Rodgers, J. A. Logan, H. Worden, S. Kulawik, A. Eldering, A. Goldman, M. W. Shephard, M. Gunson, and M. Lampel (2007), Comparison of carbon monoxide measurements by TES and MOPITT: Influence of a priori data and instrument characteristics on nadir atmospheric species retrievals, Journal of Geophysical Research: Atmospheres, 112(D9), n/a–n/a, doi:10.1029/2006JD007663.
Comparisons of tropospheric carbon monoxide (CO) volume mixing ratio profiles and total columns are presented from nadir-viewing measurements made by the Tropospheric Emission Spectrometer (TES) on the NASA Aura satellite and by the Measurements of Pollution in the Troposphere (MOPITT) instrument on the NASA Terra satellite. In this paper, we first explore the factors that relate the retrieved and the true species profiles. We demonstrate that at a given location and time the retrieved species profiles reported by different satellite instrument teams can be very different from each other. We demonstrate the influence of the a priori data and instrument characteristics on the CO products from TES and MOPITT and on their comparisons. Direct comparison of TES and MOPITT retrieved CO profiles and columns show significant differences in the lower and upper troposphere. To perform a more proper and rigorous comparison between the two instrument observations we allow for different a priori profiles and averaging kernels. We compare (1) TES retrieved CO profiles adjusted to the MOPITT a priori with the MOPITT retrievals and (2) the above adjusted TES CO profiles with the MOPITT profiles vertically smoothed by the TES averaging kernels. These two steps greatly improve the agreement between the CO profiles and the columns from the two instruments. No systematic differences are found as a function of latitude in the final comparisons. These results show that knowledge of the a priori profiles, the averaging kernels, and the error covariance matrices in the standard data products provided by the instrument teams and understanding their roles in the retrieval products are essential in quantitatively interpreting both retrieved profiles and the derived total or partial columns for scientific applications.
Peng, L., C. Zhao, Y. Lin, X. Zheng, X. Tie, and L.-Y. Chan (2007), Analysis of carbon monoxide budget in North China, Chemosphere, 66(8), 1383–1389, doi:10.1016/j.chemosphere.2006.09.055.
A global chemical transport model (MOZART-2; model of ozone and related tracers, version 2) was used to assess physical and chemical processes that control the budget of tropospheric carbon monoxide (CO) in North China. Satellite observations of CO from the measurements of pollution in the troposphere (MOPITT) instrument are combined with model results for the analysis. The comparison between the model simulations and the satellite observations of total column CO (TCO) shows that the model can reproduce the spatial and temporal distributions. However, the model results underestimate TCO by 23% in North China. This underestimation of TCO may be caused by the uncertainties of emissions. The tropospheric CO budget analysis suggests that in North China, surface emission is the largest source of tropospheric CO. The main sinks of tropospheric CO in this region are chemical reaction and stratosphere_and_troposphere exchange. The analysis also shows that most of inflow CO to Pacific regions comes from the upwind regions of North China. This transport of CO is significant during Winter and Spring time.
Ricaud, P., B. Barret, J.-L. Attié, E. Motte, E. Le Flochmoën, H. Teyssèdre, V.-H. Peuch, N. Livesey, A. Lambert, and J.-P. Pommereau (2007), Impact of land convection on troposphere-stratosphere exchange in the tropics, Atmos. Chem. Phys., 7(21), 5639–5657, doi:10.5194/acp-7-5639-2007.
The mechanism of troposphere-stratosphere exchange in the tropics was investigated from space-borne observations of the horizontal distributions of tropospheric-origin long-lived species, nitrous oxide (N2O), methane (CH4) and carbon monoxide (CO), from 150 to 70 hPa in March-April-May by the ODIN/Sub-Millimeter Radiometer (SMR), the Upper Atmosphere Research Satellite (UARS)/Halogen Occultation Experiment (HALOE) and the TERRA/Measurements Of Pollution In The Troposphere (MOPITT) instruments in 2002-2004, completed by recent observations of the AURA/Microwave Limb Sounder (MLS) instrument during the same season in 2005. The vertical resolution of the satellite measurements ranges from 2 to 4 km. The analysis has been performed on isentropic surfaces: 400 K (lower stratosphere) for all the species and 360 K (upper troposphere) only for CO. At 400 K (and 360 K for CO), all gases show significant longitudinal variations with peak-to-trough values of ∼5-11 ppbv for N2O, 0.07-0.13 ppmv for CH4, and ∼10 ppbv for CO (∼40 ppbv at 360 K). The maximum amounts are primarily located over Africa and, depending on the species, secondary more or less pronounced maxima are reported above northern South America and South-East Asia. The lower stratosphere over the Western Pacific deep convective region where the outgoing longwave radiation is the lowest, the tropopause the highest and the coldest, appears as a region of minimum concentration of tropospheric trace species. The possible impact on trace gas concentration at the tropopause of the inhomogeneous distribution and intensity of the sources, mostly continental, of the horizontal and vertical transports in the troposphere, and of cross-tropopause transport was explored with the MOCAGE Chemistry Transport Model. In the simulations, significant longitudinal variations were found on the medium-lived CO (2-month lifetime) with peak-to-trough value of ∼20 ppbv at 360 K and ∼10 ppbv at 400 K, slightly weaker than observations. However, the CH4 (8-10 year lifetime) and N2O (130-year lifetime) longitudinal variations are significantly weaker than observed: peak-to-trough values of ∼0.02 ppmv for CH4 and 1-2 ppbv for N2O at 400 K. The large longitudinal contrast of N2O and CH4 concentrations reported by the space-borne instruments at the tropopause and in the lower stratosphere not captured by the model thus requires another explanation. The suggestion is of strong overshooting over land convective regions, particularly Africa, very consistent with the space-borne Tropical Rainfall Measuring Mission (TRMM) radar maximum overshooting features over the same region during the same season. Compared to observations, the MOCAGE model forced by ECMWF analyses is found to ignore these fast local uplifts, but to overestimate the average uniform vertical transport in the UTLS at all longitudes in the tropics.
Teyssèdre, H., M. Michou, H. L. Clark, B. Josse, F. Karcher, D. Olivié, V.-H. Peuch, D. Saint-Martin, D. Cariolle, J.-L. Attié, P. Nédélec, P. Ricaud, V. Thouret, R. J. van der A, A. Volz-Thomas, and F. Chéroux (2007), A new tropospheric and stratospheric Chemistry and Transport  Model MOCAGE-Climat for multi-year studies: evaluation of the present-day climatology and sensitivity to surface processes, Atmos. Chem. Phys., 7(22), 5815–5860, doi:10.5194/acp-7-5815-2007.
We present the configuration of the Météo-France Chemistry and Transport Model (CTM) MOCAGE-Climat that will be dedicated to the study of chemistry and climate interactions. MOCAGE-Climat is a state-of-the-art CTM that simulates the global distribution of ozone and its precursors (82 chemical species) both in the troposphere and the stratosphere, up to the mid-mesosphere (∼70 km). Surface processes (emissions, dry deposition), convection, and scavenging are explicitly described in the model that has been driven by the ECMWF operational analyses of the period 2000-2005, on T21 and T42 horizontal grids and 60 hybrid vertical levels, with and without a procedure that reduces calculations in the boundary layer, and with on-line or climatological deposition velocities. Model outputs have been compared to available observations, both from satellites (TOMS, HALOE, SMR, SCIAMACHY, MOPITT) and in-situ instrument measurements (ozone sondes, MOZAIC and aircraft campaigns) at climatological timescales. The distribution of long-lived species is in fair agreement with observations in the stratosphere putting aside the shortcomings associated with the large-scale circulation. The variability of the ozone column, both spatially and temporarily, is satisfactory. However, because the Brewer-Dobson circulation is too fast, too much ozone is accumulated in the lower to mid-stratosphere at the end of winter. Ozone in the UTLS region does not show any systematic bias. In the troposphere better agreement with ozone sonde measurements is obtained at mid and high latitudes than in the tropics and differences with observations are the lowest in summer. Simulations using a simplified boundary layer lead to larger ozone differences between the model and the observations up to the mid-troposphere. NOx in the lowest troposphere is in general overestimated, especially in the winter months over the Northern Hemisphere, which may result from a positive bias in OH. Dry deposition fluxes of O3 and nitrogen species are within the range of values reported by recent inter-comparison model exercises. The use of climatological deposition velocities versus deposition velocities calculated on-line had greatest impact on HNO3 and NO2 in the troposphere.
Turquety, S., J. A. Logan, D. J. Jacob, R. C. Hudman, F. Y. Leung, C. L. Heald, R. M. Yantosca, S. Wu, L. K. Emmons, D. P. Edwards, and G. W. Sachse (2007), Inventory of boreal fire emissions for North America in 2004: Importance of peat burning and pyroconvective injection, Journal of Geophysical Research: Atmospheres, 112(D12), n/a–n/a, doi:10.1029/2006JD007281.
The summer of 2004 was one of the largest fire seasons on record for Alaska and western Canada. We construct a daily bottom-up fire emission inventory for that season, including consideration of peat burning and high-altitude (buoyant) injection, and evaluate it in a global chemical transport model (the GEOS-Chem CTM) simulation of CO through comparison with MOPITT satellite and ICARTT aircraft observations. The inventory is constructed by combining daily area burned reports and MODIS fire hot spots with estimates of fuel consumption and emission factors based on ecosystem type. We estimate the contribution from peat burning using drainage and peat distribution maps for Alaska and Canada; 17% of the reported 5.1 × 106 ha burned were located in peatlands in 2004. Our total estimate of North American fire emissions during the summer of 2004 is 30 Tg CO, including 11 Tg from peat. Including peat burning in the GEOS-Chem simulation improves agreement with MOPITT observations. The long-range transport of fire plumes observed by MOPITT suggests that the largest fires injected a significant fraction of their emissions in the upper troposphere.
Warner, J., M. M. Comer, C. D. Barnet, W. W. McMillan, W. Wolf, E. Maddy, and G. Sachse (2007), A comparison of satellite tropospheric carbon monoxide measurements from AIRS and MOPITT during INTEX-A, Journal of Geophysical Research (Atmospheres), 112(d11), 12, doi:10.1029/2006JD007925.
Satellite CO measurements from Measurements of Pollution in the Troposphere (MOPITT) and Atmospheric Infrared Sounder (AIRS) were used in the Intercontinental Chemical Transport Experiment-North America (INTEX-A) by the flight planning team to monitor local emissions and the transport of polluted air masses. Because simultaneous measurements of tropospheric CO from both AIRS and MOPITT were used by different investigators during this experiment, a cross reference and comparison are necessary to understand these two data sets and their impacts to the scientific conclusions developed from them. The global CO mixing ratios at 500 mbar, as well as the CO total column amount, are compared between the two instruments for both direct comparison and the comparison using the same a priori profile for the period from 15 June to 14 August 2004. Also presented are the comparisons of the remotely sensed profiles by AIRS, MOPITT, and the in situ profiles collected by the DACOM. In summary, both sensors agree very well on the horizontal distributions of CO represented by the high correlation coefficients (0.7-0.98), and they agree on the CO concentrations to within an average of 10-15 ppbv. Over land, the CO variability is higher, and the correlations between the two data sets are relatively lower than over ocean; however, there is no evidence of a systematic bias. Over the oceans where the CO concentration is smaller in the lower atmosphere, AIRS-MOPITT show a positive bias of 15-20 ppbv and the details are presented.
Ying, L., Z. Chunsheng, F. Yuanyuan, and Y. Huan (2007), Analysis of Distribution and Seasonal Change of Tropospheric Ozone Residual in Recent 20 Years Using Satellite Data, Journal of Applied Meteorological Science, 18(2), 181–186.
Ozone is an important trace gas in the atmosphere. Tropospheric ozone is an essential component of photochemical smog, and it is one of the major indexes that reflect the atmosphere pollution from human activities. In the tropospheric atmosphere, there is a close relationship among the tropospheric ozone, carbon monoxide and nitrogen dioxide. And in tropospheric photochemistry, tropospheric carbon monoxide and nitrogen dioxide are important precursors of tropospheric ozone. The global and regional distribution of tropospheric ozone residual in recent 20 years and the possible reasons leading to the high tropospheric ozone residual concentration are analyzed using satellite data. These satellite data include 2002--2004 carbon monoxide data from Measurement of Pollution in the Troposphere (MOPITT) on TERRA, 1996--2002 nitrogen dioxide data from Global Ozone Monitoring Experiment (GOME) on ERS-2 launched in 1995, 2003--2005 nitrogen dioxide data from SCanning Imaging Absorption SpectroMeter for Atmospheric CHartograph Y (SCIAMACHY) on Envisate-1 launched in 2002, and the 1979--2000 tropospheric ozone residual data derived from Total Ozone Mapping Spectrometer (TOMS). From the data analysis, it can be found that distribution patterns of high tropospheric ozone residual areas are related to the high carbon monoxide column and nitrogen dioxide column areas. Biomass and biofuel burning might be responsible for the peak tropospheric ozone residual centers in the tropical regions of South America and southern parts of Africa. High carbon monoxide and nitrogen dioxide emissions in big city are the main contributors to high tropospheric ozone residual in East America, East Asia and Northern parts of India. The variation of tropospheric ozone residual has an obvious correlation with the circle of sun radiation. There is a significant seasonal variation for the tropospheric ozone residual in the middle and high latitudes. The tropospheric ozone residual of north hemisphere reaches the peak in summer, the second peak appears in spring, and the value of tropospheric ozone residual is minimal in winter. The tropospheric ozone residual of southern hemisphere reaches the peak in spring and the value of tropospheric ozone residual is minimal in autumn. In China, the seasonal variation is conform to the northern hemisphere. And the areas of high tropospheric ozone residual concentration are converged in Szechwan basin and eastern seacoast of China where the total number of people is large and the industry is well developed. In the Tibetan Plateau the tropospheric ozone residual "concentration is always in relative low level.
Zhao, C., L. Peng, X. Tie, Y. Lin, C. Li, X. Zheng, and Y. Fang (2007a), A High CO Episode of Long-Range Transport Detected by MOPITT, Water Air Soil Pollut, 178(1–4), 207–216, doi:10.1007/s11270-006-9191-1.
Recent developments in satellite remote sensing technologies resulted in the ability to observe major pollution events such as dust and smoke around the world on a daily basis. Satellite imagery can sometimes detect long-range transport episodes. In this paper, a high CO episode at remote GAW station, Mt. Waliguan, detected by MOPITT CO dataset during the end of April 2002, is described. CO concentrations above 600 hPa almost doubled on 27 April and CMDL surface sample measurements also observed this significant CO enhancement. Using NCEP data, satellite fire products data and backward trajectory model we suggest that this high CO episode of 27 April is not a local pollution event, but that it is due to long-range transport from active biomass burning and biofuel burning areas located in the border areas of Pakistan and India. The trajectory cluster analysis shows that the origins of 5-day backward trajectories, for air masses reaching Mt. Waliguan station, at all altitudes, mainly overlap with the fire spot locations detected by TRMM data and biofuel burning in India.
Zhao, C., Y. Fang, J. Tang, X. Zheng, and G. Zhou (2007b), Distribution of Carbon Monoxide from MOPITT of 2000--2004 and Comparisons with Surface Measurements in Mt. Waliguan Station, Journal of Applied Meteorological Science, 18(1), 36–41.
Carbon monoxide (CO) is one of the main pollutants produced by incomplete combustion processes, such as the burning of fossil fuels in urban and industrial areas as well as by biofuel and biomass burning. CO has long been recognized for its critical role in tropospheric chemistry. Coupled with a one to three month lifetime, the wide variety and seasonal variation of sources makes CO an excellent tracer of atmospheric motions. Surface CO measurements which have generally been limited to surface or boundary layer measurements often substantially impacted by local pollution can not provided a global synoptic view of CO on a daily basis. To better understand global CO cycles, observations from the space are necessary. The Measurements of Pollution in the Troposphere (MOPITT) instrument, funded by the Canadian Space Agency and manufactured by COM DEV of Cambridge, Ontario, is launched onboard the NASA Earth Observing System (EOS) Terra satellite in December, 1999. MOPITT offers the first daily, global synoptic observations of CO since March 2000. The MOPITT data set contains CO total column amount, CO mixing ratios at six altitudes (850 hPa, 700 hPa, 500 hPa, 350 hPa, 250 hPa, 150 hPa) and the corresponding location and time along the track. Here Level 2, Version 3 MOPITT CO data are used which includes the latitude and longitude of MOPITT at nadir, the corresponding CO column and six layers of CO mixing ratio. The data are aggregated and interpolated to achieve grid data with a resolution of 1 degree x1 degree at 3-day average. Distribution properties and trend of CO from MOPITT of March 2000 to May 2004 are analyzed and comparisons with CMDL/NOAA surface CO measurements in Mt. Waliguan station are made. The results show that there is a large variation for global CO distribution. On the average, CO in Northern hemisphere is higher than that in Southern hemisphere. CO peak centers are located in East Asia, West Europe and North America in Northern hemisphere while in Middle West Africa and tropic regions of South America in Southern hemisphere. There is a significant seasonal variation for CO with a peak concentration in spring time in Northern hemisphere and in Autumn in Southern hemisphere. CO concentrations are high over coast regions of China and Japan all along a year. CO at Sichuan Basin which is located in the east of Qinghai-Tibet Plateau are higher than that of its surrounding regions. Trends analysis of Beijing and Mt. Waliguan suggests that CO concentrations over these two regions increase during 2000--2004. Comparisons with CMDL/NOAA surface CO measurement in Mt. Waliguan shows that the variations of these two datasets agree well and there is a significant correlation between MOPITT CO column and CMDL surface measurements. The increasing trend for CO during 2000--2004 obtained from these two datasets is at magnitude of a few thousandth.
Zhou, D. K., A. M. Larar, X. Liu, W. L. Smith, J. P. Taylor, S. M. Newman, G. W. Sachse, and S. A. Mango (2007), NAST-I tropospheric CO retrieval validation during INTEX-NA and EAQUATE, Q. J. R. Meteorol. Soc., 133(S3), 233–241, doi:10.1002/qj.130.
Troposphere carbon monoxide (CO), as well as other trace species retrieved with advanced ultraspectral remote sensors of Earth observing satellites, is critical in air quality observation, modelling, and forecasting. The retrieval algorithm and the accuracy of the parameters retrieved from passive satellite remote sounders must be validated. The Intercontinental Chemical Transport Experiment - North America (INTEXNA) and the European Aqua Thermodynamic Experiment (EAQUATE) provide important validation of satellite observations with ongoing satellite measurement programmes such as Terra, Aura, and Aqua. One of the experimental objectives is to validate chemical species observed from ultraspectral sounders with aircraft in situ measurements, such as the NPOESS Airborne Sounder Testbed-Interferometer (NAST-I). Detailed intercomparisons between aircraft in situ measured and NAST-I retrieved CO profiles were performed to assess the retrieval capability of a passive infrared spectral remote sounder. Validation results illustrate that the CO vertical structure can be obtained by the NAST-I. The thermal radiances are most sensitive to CO emissions from the free troposphere. However, the profile retrieval accuracy depends on the CO uncertainty in the terrestrial boundary layer. It is shown here that the CO distribution in the terrestrial boundary layer over the sea cannot be obtained with reliable accuracy where there is little contrast between the surface air and surface skin temperature. Copyright © 2007 Royal Meteorological Society

2006

Arellano, A. F., and P. G. Hess (2006), Sensitivity of top-down estimates of CO sources to GCTM transport, Geophysical Research Letters, 33(21), n/a–n/a, doi:10.1029/2006GL027371.
Estimates of CO sources derived from inversions using satellite observations still exhibit discrepancies. Here, we conduct controlled inverse analyses to elucidate the influence of model transport on the robustness of regional CO source estimates. We utilized Model of Ozone and Related chemical Tracers global chemical transport models (GCTM) driven by National Centers for Environmental Prediction and European Centre for Medium-Range Weather Forecast reanalyses, and GEOS-Chem GCTM driven by Global Modeling and Assimilation Office assimilated meteorology to generate response functions for prescribed regional CO sources. We find that inter-model differences in CO due to differences in transport are within 10–30% of inter-model mean CO concentration. However, these differences can translate to regionally significant spread in source estimates. While we find that CO source estimates for East Asia and North Africa are reasonably robust, we find inconsistencies and inter-model spread of greater than 40% in our source estimates for Indonesia, South America, Europe and Russia. This indicates the need for rigorous assessment on uncertainties in top-down source estimates through model inter-comparisons and ensemble approaches.
Arellano, A. F., P. S. Kasibhatla, L. Giglio, G. R. van der Werf, J. T. Randerson, and G. J. Collatz (2006), Time-dependent inversion estimates of global biomass-burning CO emissions using Measurement of Pollution in the Troposphere (MOPITT) measurements, Journal of Geophysical Research (Atmospheres), 111(d10), 9303, doi:10.1029/2005JD006613.
We present an inverse-modeling analysis of CO emissions using column CO retrievals from the Measurement of Pollution in the Troposphere (MOPITT) instrument and a global chemical transport model (GEOS-CHEM). We first focus on the information content of MOPITT CO column retrievals in terms of constraining CO emissions associated with biomass burning and fossil fuel/biofuel use. Our analysis shows that seasonal variation of biomass-burning CO emissions in Africa, South America, and Southeast Asia can be characterized using monthly mean MOPITT CO columns. For the fossil fuel/biofuel source category the derived monthly mean emission estimates are noisy even when the error statistics are accurately known, precluding a characterization of seasonal variations of regional CO emissions for this source category. The derived estimate of CO emissions from biomass burning in southern Africa during the June-July 2000 period is significantly higher than the prior estimate (prior, 34 Tg; posterior, 13 Tg). We also estimate that emissions are higher relative to the prior estimate in northern Africa during December 2000 to January 2001 and lower relative to the prior estimate in Central America and Oceania/Indonesia during April-May and September-October 2000, respectively. While these adjustments provide better agreement of the model with MOPITT CO column fields and with independent measurements of surface CO from National Oceanic and Atmospheric Administration Climate Monitoring and Diagnostics Laboratory at background sites in the Northern Hemisphere, some systematic differences between modeled and measured CO fields persist, including model overestimation of background surface CO in the Southern Hemisphere. Characterizing and accounting for underlying biases in the measurement model system are needed to improve the robustness of the top-down estimates.
Bowman, K. P. (2006), Transport of carbon monoxide from the tropics to the extratropics, Journal of Geophysical Research: Atmospheres, 111(D2), n/a–n/a, doi:10.1029/2005JD006137.
Global observations of carbon monoxide (CO) from the Measurements of Pollution in the Troposphere (MOPITT) instrument on the NASA Terra satellite and three-dimensional trajectories computed from analyzed winds are used independently to study the transport of air from the tropics to the extratropics. During southern hemisphere spring (September through November), biomass burning in the southern tropics produces large-scale plumes of CO. These plumes can be easily distinguished from the clean air of the southern hemisphere extratropics. Both total column CO maps and latitude-height cross-sections of CO show a strong gradient of CO between 30 and 40°S. Climatological trajectory calculations show that air originating in the lower troposphere near the tropical biomass-burning regions generally rises into the middle and upper troposphere, where it is entrained in the equatorward side of the subtropical jet. While the zonal dispersion of air parcels within the tropics and subtropics is relatively rapid, air disperses rather slowly across the jet. The MOPITT CO data thus confirm the results from the trajectory analysis that transport from the tropics to the extratropics is a comparatively slow process. This gives rise to the appearance of “transport barriers” in the subtropics.
Buchwitz, M., R. de Beek, S. Noël, J. P. Burrows, H. Bovensmann, O. Schneising, I. Khlystova, M. Bruns, H. Bremer, P. Bergamaschi, S. Körner, and M. Heimann (2006), Atmospheric carbon gases retrieved from SCIAMACHY by WFM-DOAS:  version 0.5 CO and CH4 and impact of calibration improvements on CO2 retrieval, Atmos. Chem. Phys., 6(9), 2727–2751, doi:10.5194/acp-6-2727-2006.
The three carbon gases carbon monoxide (CO), carbon dioxide (CO2), and methane (CH4) are important atmospheric constituents affecting air quality and climate. The near-infrared nadir spectra measured by SCIAMACHY on ENVISAT contain information on the vertical columns of these gases which we retrieve using a modified DOAS algorithm (WFM-DOAS or WFMD). Our main data products are CO vertical columns and dry-air column averaged mixing ratios of methane (CH4) and CO2 (denoted XCH4 and XCO2). For CO and CH4 we present new results for the year 2003 obtained with an improved version of WFM-DOAS (WFMDv0.5) retrieved from Level 1 version 4 (Lv1v4) spectra. This data set has recently been compared with a network of ground based FTIR stations. Here we describe the WFMDv0.5 algorithm, present global and regional maps, and comparisons with global reference data. We show that major problems of the previous versions (v0.4 and v0.41) related to the varying ice-layer on the SCIAMACHY channel 8 detector have been solved. Compared to MOPITT the SCIAMACHY CO columns are on average higher by about 10-20%. Regionally, however, especially over central South America, differences can be much larger. For methane we present global and regional maps which are compared to TM5 model simulations performed using standard methane emission inventories. We show that methane source regions can be clearly detected with SCIAMACHY. We also show that the methane data product can be significantly further improved using Lv1v5 spectra with improved calibration. For CO2 we present three years of SCIAMACHY CO2 measurements over Park Falls, Wisconsin, USA, retrieved from Lv1v5. We show that the quality of CO2 retrieved from these spectra is significantly higher compared to WFMDv0.4 XCO2 retrieved from Lv1v4.
Choi, S.-D., and Y.-S. Chang (2006a), Carbon monoxide monitoring in Northeast Asia using MOPITT: Effects of biomass burning and regional pollution in April 2000, Atmospheric Environment, 40(4), 686–697, doi:10.1016/j.atmosenv.2005.09.081.
To assess the influence of biomass burning and regional pollution on CO levels in Northeast Asia, trajectory analysis and satellite observations from the Measurement of Pollution in the Troposphere (MOPITT) instrument were applied. As a case study, data for April 2000 were used. Ground measurement data at remote sites in Korea showed high CO levels and did not have typical seasonal variations due to regional pollution. Therefore, MOPITT data over the East/Japan Sea was recommended for identification of long-range transport of CO. The locations of biomass burning, distribution of MOPITT CO, and backward trajectories clearly indicated that Siberian fires and industrial activities in East China affected CO levels in Korea and Japan. CO levels over East China for the first two weeks were enhanced more than 35 ppb by biomass burning in Myanmar and Indo-China, and high CO levels over the East/Japan Sea for the last two weeks were affected by both anthropogenic emissions and biomass burning. The average difference in CO concentrations over the East/Japan Sea between fire days (217±18 ppb) and non-fire days (186±15 ppb) was 31 ppb (p&lt;0.05). These results suggest again that regional pollution as well as biomass burning plays an important role for CO levels in Northeast Asia and that MOPITT is a promising tool for the comprehensive understanding of CO emissions and transport.
Choi, S.-D., and Y.-S. Chang (2006b), Evaluation of Carbon Uptake and Emissions by Forests in Korea During the Last Thirty Years (1973–2002), Environ Monit Assess, 117(1–3), 99–107, doi:10.1007/s10661-006-7982-x.
The contribution of Korean forests to carbon sequestration for anthropogenic carbon emissions was evaluated. In addition, monitoring of carbon species released from forest fires was conducted. Despite a high carbon uptake by Korean forests, a tremendous increase in fossil fuel burning resulted in a small contribution by forests to carbon removal. The removal efficiency had a 5–31% range with an average of 12% during the period 1973–2002. In 2000, the amount of carbon released from burned trees corresponded to 1.6% of carbon uptake by forests. The distribution of surface CO concentration (ppb) derived from MOPITT (Measurement of Pollution in the Troposphere) showed high CO levels over the East/Japan Sea on April 10, 2000 when the largest forest fires occurred along the east coast of Korea. Trajectory analysis and ground CO measurements also indicated that CO levels over the East/Japan Sea were influenced by forest fires. This study suggests that continuous monitoring of carbon emissions from forest fires is needed for a more reliable estimate of carbon flux in the environment.
Edwards, D. P., L. K. Emmons, J. C. Gille, A. Chu, J.-L. Attié, L. Giglio, S. W. Wood, J. Haywood, M. N. Deeter, S. T. Massie, D. C. Ziskin, and J. R. Drummond (2006a), Satellite-observed pollution from Southern Hemisphere biomass burning, Journal of Geophysical Research: Atmospheres, 111(D14), 14312, doi:10.1029/2005JD006655.
Biomass burning is a major source of pollution in the tropical Southern Hemisphere, and fine mode carbonaceous particles are produced by the same combustion processes that emit carbon monoxide (CO). In this paper we examine these emissions with data from the Terra satellite, CO profiles from the Measurement of Pollution in the Troposphere (MOPITT) instrument, and fine-mode aerosol optical depth (AOD) from the Moderate-Resolution Imaging Spectroradiometer (MODIS). The satellite measurements are used in conjunction with calculations from the MOZART chemical transport model to examine the 2003 Southern Hemisphere burning season with particular emphasis on the months of peak fire activity in September and October. Pollutant emissions follow the occurrence of dry season fires, and the temporal variation and spatial distributions of MOPITT CO and MODIS AOD are similar. We examine the outflow from Africa and South America with emphasis on the impact of these emissions on clean remote regions. We present comparisons of MOPITT observations and ground-based interferometer data from Lauder, New Zealand, which indicate that intercontinental transport of biomass burning pollution from Africa often determines the local air quality. The correlation between enhancements of AOD and CO column for distinct biomass burning plumes is very good with correlation coefficients greater than 0.8. We present a method using MOPITT and MODIS data for estimating the emission ratio of aerosol number density to CO concentration which could prove useful as input to modeling studies. We also investigate decay of plumes from African fires following export into the Indian Ocean and compare the MOPITT and MODIS measurements as a way of estimating the regional aerosol lifetime. Vertical transport of biomass burning emissions is also examined using CO profile information. Low-altitude concentrations are very high close to source regions, but further downwind of the continents, vertical mixing takes place and results in more even CO vertical distributions. In regions of significant convection, particularly in the equatorial Indian Ocean, the CO mixing ratio is greater at higher altitudes, indicating vertical transport of biomass burning emissions to the upper troposphere.
Edwards, D. P., G. Pétron, P. C. Novelli, L. K. Emmons, J. C. Gille, and J. R. Drummond (2006b), Southern Hemisphere carbon monoxide interannual variability observed by Terra/Measurement of Pollution in the Troposphere (MOPITT), Journal of Geophysical Research: Atmospheres, 111(D16), n/a–n/a, doi:10.1029/2006JD007079.
Biomass burning is an annual occurrence in the tropical Southern Hemisphere (SH) and represents a major source of regional pollution. Vegetation fires emit carbon monoxide (CO), which because of its medium lifetime is an excellent tracer of tropospheric transport. CO is also one of the few tropospheric trace gases currently observed from satellite, and this provides long-term global measurements. In this paper, we use the 5-year CO data record from the Measurement of Pollution in the Troposphere (MOPITT) instrument to examine the interannual variability of the SH CO loading and show how this relates to climate conditions which determine the intensity of fire sources. The MOPITT observations show an annual austral springtime peak in the SH zonal CO loading each year with dry season biomass burning emissions in South America, southern Africa, the maritime continent, and northwestern Australia. Although fires in southern Africa and South America typically produce the greatest amount of CO, the most significant interannual variation is due to varying fire activity and emissions from the maritime continent and northern Australia. We find that this variation in turn correlates well with the El Niño–Southern Oscillation precipitation index. Between 2000 and 2005, emissions were greatest in late 2002, and an inverse modeling of the MOPITT data using the Model of Ozone Research in the Troposphere (MOZART) chemical transport model estimates the Southeast Asia regional fire source for the year August 2002 to September 2003 to be 52 Tg CO. Comparison of the MOPITT retrievals and NOAA surface network measurements indicate that the latter do not fully capture the interannual variability or the seasonal range of the CO zonal average concentration because of biases associated with atmospheric and geographic sampling.
Guerova, G., I. Bey, J.-L. Attié, R. V. Martin, J. Cui, and M. Sprenger (2006), Impact of transatlantic transport episodes on summertime ozone in Europe, Atmos. Chem. Phys., 6(8), 2057–2072, doi:10.5194/acp-6-2057-2006.
This paper reports on the transport of ozone (O3) and related species over the North Atlantic ocean and its impact on Europe. Measurements of nitrogen dioxide (NO2) and carbon monoxide (CO) columns from the GOME and MOPITT satellite instruments, respectively, are used in conjunction with the GEOS-CHEM global model of transport and tropospheric chemistry to identify the major events of long range transport that reach Europe over the course of summer 2000. Sensitivity model simulations are used to analyse observed O3 distributions with respect to the impact of long range transport events. For that purpose, we used in-situ O3 observations taken at the mountain site of Jungfraujoch as well as O3 vertical profiles taken in the vicinity of central European cities. Over the course of summer 2000, we identified 9 major episodes of transatlantic pollution transport; 7 events are associated with transient cyclones while 2 events occur through zonal transport (e.g. by advection in the strong low-level westerly winds established in summer between the Azores anticyclone and transient cyclones). We find that on average three episodes occur per month with the strongest ones being in June. The number and frequency of long range transport events that reach Europe are driven by the position and strength of the Azores anticyclone. Model sensitivity simulations indicate that the summer mean North American O3 contribution ranges from 3 to 5 ppb (7-11%) in the planetary boundary layer and 10 to 13 ppb (18-23%) in the middle and upper troposphere. During particular episodes, North American sources can result in O3 enhancements up to 25-28 ppb in the layer between 800-600 hPa and 10-12 ppb in the boundary layer. The impact of the zonal transport events on O3 distribution over Europe is more clearly seen below 700 hPa as they tend to transport pollution at lower levels while the events associated with transient cyclones are more likely to have an impact on the middle and upper troposphere (i.e. above 600 hPa). The air mass origins found in the GEOS-CHEM model are clearly confirmed by back trajectory analyses. During most of the 9 events, a strong contribution in North American O3 is in general associated with only little European O3 and vice-versa (in particular at the Jungfraujoch). A substantial North American contribution (e.g., 30% or higher) to O3 over Europe does not always result in pronounced O3 enhancements in the observations during our period of study.
Kar, J., J. R. Drummond, D. B. A. Jones, J. Liu, F. Nichitiu, J. Zou, J. C. Gille, D. P. Edwards, and M. N. Deeter (2006), Carbon monoxide (CO) maximum over the Zagros mountains in the Middle East: Signature of mountain venting?, Geophysical Research Letters, 33(15), n/a–n/a, doi:10.1029/2006GL026231.
We report an intriguing feature observed in daytime measurements of CO over the Middle East, in spring and summer, by the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument. Enhanced CO is observed over the Zagros mountains of Iran, following the local topography over this region (25–40N, 40–60E). The MOPITT averaging kernels do not seem to indicate any data artifacts in this area. We argue that this feature likely forms by the process of mountain venting by thermal winds caused by strong daytime differential heating. This is consistent with an analysis of vertical velocity in the NCEP reanalysis data in this region. The phenomenon was observed in all the years of available MOPITT measurements and may have implications for the pollution episodes in the region and the Middle East ozone maximum that has been observed earlier.
de Laat, A. T. J., A. M. S. Gloudemans, H. Schrijver, M. M. P. van den Broek, J. F. Meirink, I. Aben, and M. Krol (2006), Quantitative analysis of SCIAMACHY carbon monoxide total column measurements, Geophysical Research Letters, 33(7), n/a–n/a, doi:10.1029/2005GL025530.
This paper presents a first quantitative and systematic analysis of one year of SCIAMACHY Carbon Monoxide (CO) total column retrievals from the IMLM algorithm (v6.3) using a chemistry-transport model simulation. The global distribution of modeled and measured CO show similar spatial patterns: a north-south gradient, low CO over mountains, and high CO over emission regions. CO column errors due to instrument noise are closely related to surface albedo and are less than 6% for monthly means at high surface albedo locations, improving to ∼1% for ideal circumstances: cloud-free pixels, high surface albedo, and spatial averaging (3° × 2°). Quantitative comparison shows that measured and modeled seasonality agree very well at several locations with different types of seasonal cycles. Differences between SCIAMACHY CO and model results are less than 13% except for regions with large instrument-noise errors. Differences larger than the 2σ instrument-noise error (95% confidence interval) occur in some regions with small noise errors, for example southern Africa. In this case the SCIAMACHY CO variations are different from the model biomass-burning emission seasonal cycle and more in agreement with observed fire count seasonality. The comparison with model results indicates that despite unforeseen time-dependent instrument-calibration complications, SCIAMACHY CO total column retrievals are of sufficient quality to provide useful new information on the global distribution and variation of CO.
Liu, J., J. R. Drummond, D. B. A. Jones, Z. Cao, H. Bremer, J. Kar, J. Zou, F. Nichitiu, and J. C. Gille (2006), Large horizontal gradients in atmospheric CO at the synoptic scale as seen by spaceborne Measurements of Pollution in the Troposphere, Journal of Geophysical Research: Atmospheres, 111(D2), n/a–n/a, doi:10.1029/2005JD006076.
We have examined the influence of synoptic processes on the distribution of atmospheric CO as observed by the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument. In the MOPITT data, large horizontal gradients in CO, coherent at the synoptic scale, have been observed. The concentration of CO varies rapidly by as much as 50–100% across distances of ∼100 km, forming distinct boundaries in the CO distribution. These can last one to several days and span horizontal distances of 600–1000 km. On average, such events were observed in the MOPITT CO daily images once every 3–4 days over North America in spring and summer 2000. We focused on three case studies over North America in August 2000 to understand the mechanisms responsible for the large gradients in CO. Through an analysis of meteorological data from the National Centers for Environmental Prediction/National Center for Atmospheric Research Reanalysis, parcel trajectory modeling, and global three-dimensional chemical transport modeling, we found that the large horizontal gradients typically reflect the differential vertical and horizontal transport of air with different chemical signatures. In the first case, the large gradients in CO over North Dakota resulted from the lifting ahead of a cold front that transported boundary layer air enriched with CO from forest fires in Montana, combined with the descent of clean air from the Canadian Prairies behind the front. In the second case, the large gradients over northeastern Texas were produced by the convective lifting over Arkansas of air with high concentrations of CO from the oxidation of volatile organic compounds and the onshore transport of clean air from the Gulf of Mexico. In the third case, we examined an example of outflow of surface pollution from North America by a cyclone. The largest gradients in this case were observed along the boundary between the boundary layer air transported by the warm conveyor belt ahead of the cold front and the clean air transported from the Atlantic by the semipermanent high-pressure system in the central Atlantic. Our results demonstrate that MOPITT can capture the influence of synoptic processes on the horizontal and vertical distribution of CO. The large gradients in CO observed on synoptic scales represent valuable information that can be exploited to improve our understanding of atmospheric CO. In particular, these results suggest that the MOPITT observations provide a useful data set with which to address a range of issues from air quality on local/regional scales to long-range transport of pollution on continental/global scales.
Manual, T. K., A. Khan, Y. N. Ahammed, R. S. Tanwar, R. S. Parmar, K. S. Zalpuri, P. K. Gupta, S. L. Jain, R. Singh, A. P. Mitra, S. C. Garg, A. Suryanarayana, V. S. N. Murty, M. D. Kumar, and A. J. Shepherd (2006), Observations of trace gases and aerosols over the Indian Ocean during the monsoon transition period, J Earth Syst Sci, 115(4), 473–484, doi:10.1007/BF02702875.
Characteristics of trace gases (O3, CO, CO2, CH4 and N2O) and aerosols (particle size of 2.5 micron) were studied over the Arabian Sea, equatorial Indian Ocean and southwest part of the Bay of Bengal during the monsoon transition period (October–November, 2004). Flow of pollutants is expected from south and southeast Asia during the monsoonal transition period due to the patterns of wind flow which are different from the monsoon period. This is the first detailed report on aerosols and trace gases during the sampled period as the earlier Bay of Bengal Experiment (BOBMEX), Arabian Sea Monsoon Experiment (ARMEX) and Indian Ocean Experiments (INDOEX) were during monsoon seasons. The significant observations during the transition period include: (i) low ozone concentration of the order of 5 ppbv around the equator, (ii) high concentrations of CO2, CH4 and N2O and (iii) variations in PM2.5 of 5–20μg/m3.
Massie, S. T., J. C. Gille, D. P. Edwards, and S. Nandi (2006), Satellite observations of aerosol and CO over Mexico City, Atmospheric Environment, 40(31), 6019–6031, doi:10.1016/j.atmosenv.2005.11.065.
The development of remote sensing satellite technology potentially will lead to the technical means to monitor air pollution emitted from large cities on a global basis. This paper presents observations by the moderate resolution imaging spectroradiometer (MODIS) and measurements of pollution in the troposphere (MOPITT) experiments of aerosol optical depths and CO mixing ratios, respectively, in the vicinity of Mexico City to illustrate current satellite capabilities. MOPITT CO mixing ratios over Mexico City, averaged between January–March 2002–2005, are 19% above regional values and the CO plume extends over 10°2 in the free troposphere at 500 hPa. Time series of Red Automatica de Monitoreo Ambiental (RAMA) PM10, and (Aerosol Robotic Network) AERONET and MODIS aerosol optical depths, and RAMA and MOPITT CO time series are inter-compared to illustrate the different perspectives of ground based and satellite instrumentation. Finally, we demonstrate, by examining MODIS and MOPITT data in April 2003, that satellite data can be used to identify episodes in which pollution form fires influences the time series of ground based and satellite observations of urban pollution.
Pradier, S., J.-L. Attie, M. Chong, J. Escobar, V.-H. Peuch, J.-F. Lamarque, B. Khattatov, and D. Edwards (2006), Evaluation of 2001 springtime CO transport over West Africa using MOPITT CO measurements assimilated in a global chemistry transport model, Tellus B, 58(3), 163–176, doi:10.1111/j.1600-0889.2006.00185.x.
The global chemistry and transport model MOCAGE (Modèle de Chimie Atmosphérique à Grande Echelle) is used to investigate the contribution of transport to the carbon monoxide (CO) distribution over West Africa during spring 2001. It is constrained with the CO profiles provided by the Measurements Of Pollution In The Troposphere (MOPITT) instrument through a sequential assimilation technique based on a suboptimal Kalman filter. The improvement of tropospheric CO distribution from MOCAGE is evaluated by comparing the model results (with and without assimilation) with the MOPITT CO concentrations observed during the analysed period (between 2001 March 15 to 2001 April 30), and also with independent in situ CMDL and TRACE-P observations. The initial overestimation in high CO emissions areas (Africa, SE Asia and NW coast of South America) is considerably reduced by using the MOPITT CO assimilation. We analysed the assimilated CO for a period of three successive 15 d periods in terms of average fields over West Africa and contributions to the CO budget of transport and chemical sources. It is found that the horizontal and vertical CO distributions are strongly dependent on the characteristics of the large-scale flows during spring, marked by the onset of the low-level southerly monsoon flow and the gradual increase of the well-known African and tropical easterly jets at middle and upper levels, respectively. Total transport by the mean flow (horizontal plus vertical advection) is important in the CO budget since it mostly compensates the local sink or source generated by chemical reactions and small-scale processes. The major source of CO is concentrated in the lower troposphere (1000-800 hPa) mainly due to convergent low-level flow advecting CO from surrounding regions and surface emissions (biomass burning). Vertical transport removes 70% of this low-level CO and redistributes it in the middle troposphere (800-400 hPa) where chemical reactions and horizontal exports contribute to the loss of CO. A lesser proportion is transported upwards into upper troposphere, and then horizontally, out of the considered domain.
Rinsland, C. P., M. Luo, J. A. Logan, R. Beer, H. Worden, S. S. Kulawik, D. Rider, G. Osterman, M. Gunson, A. Eldering, A. Goldman, M. Shephard, S. A. Clough, C. Rodgers, M. Lampel, and L. Chiou (2006), Nadir measurements of carbon monoxide distributions by the Tropospheric Emission Spectrometer instrument onboard the Aura Spacecraft: Overview of analysis approach and examples of initial results, Geophysical Research Letters, 33(22), n/a–n/a, doi:10.1029/2006GL027000.
We provide an overview of the nadir measurements of carbon monoxide (CO) obtained thus far by the Tropospheric Emission Spectrometer (TES). The instrument is a high resolution array Fourier transform spectrometer designed to measure infrared spectral radiances from low Earth orbit. It is one of four instruments successfully launched onboard the Aura platform into a sun synchronous orbit at an altitude of 705 km on July 15, 2004 from Vandenberg Air Force Base, California. Nadir spectra are recorded at 0.06-cm−1 spectral resolution with a nadir footprint of 5 × 8 km. We describe the TES retrieval approach for the analysis of the nadir measurements, report averaging kernels for typical tropical and polar ocean locations, characterize random and systematic errors for those locations, and describe instrument performance changes in the CO spectral region as a function of time. Sample maps of retrieved CO for the middle and upper troposphere from global surveys during December 2005 and April 2006 highlight the potential of the results for measurement and tracking of global pollution and determining air quality from space.
Shindell, D. T., G. Faluvegi, D. S. Stevenson, M. C. Krol, L. K. Emmons, J.-F. Lamarque, G. Pétron, F. J. Dentener, K. Ellingsen, M. G. Schultz, O. Wild, M. Amann, C. S. Atherton, D. J. Bergmann, I. Bey, T. Butler, J. Cofala, W. J. Collins, R. G. Derwent, R. M. Doherty, J. Drevet, H. J. Eskes, A. M. Fiore, M. Gauss, D. A. Hauglustaine, L. W. Horowitz, I. S. A. Isaksen, M. G. Lawrence, V. Montanaro, J.-F. Müller, G. Pitari, M. J. Prather, J. A. Pyle, S. Rast, J. M. Rodriguez, M. G. Sanderson, N. H. Savage, S. E. Strahan, K. Sudo, S. Szopa, N. Unger, T. P. C. van Noije, and G. Zeng (2006), Multimodel simulations of carbon monoxide: Comparison with observations and projected near-future changes, Journal of Geophysical Research: Atmospheres, 111(D19), n/a–n/a, doi:10.1029/2006JD007100.
We analyze present-day and future carbon monoxide (CO) simulations in 26 state-of-the-art atmospheric chemistry models run to study future air quality and climate change. In comparison with near-global satellite observations from the MOPITT instrument and local surface measurements, the models show large underestimates of Northern Hemisphere (NH) extratropical CO, while typically performing reasonably well elsewhere. The results suggest that year-round emissions, probably from fossil fuel burning in east Asia and seasonal biomass burning emissions in south-central Africa, are greatly underestimated in current inventories such as IIASA and EDGAR3.2. Variability among models is large, likely resulting primarily from intermodel differences in representations and emissions of nonmethane volatile organic compounds (NMVOCs) and in hydrologic cycles, which affect OH and soluble hydrocarbon intermediates. Global mean projections of the 2030 CO response to emissions changes are quite robust. Global mean midtropospheric (500 hPa) CO increases by 12.6 ± 3.5 ppbv (16%) for the high-emissions (A2) scenario, by 1.7 ± 1.8 ppbv (2%) for the midrange (CLE) scenario, and decreases by 8.1 ± 2.3 ppbv (11%) for the low-emissions (MFR) scenario. Projected 2030 climate changes decrease global 500 hPa CO by 1.4 ± 1.4 ppbv. Local changes can be much larger. In response to climate change, substantial effects are seen in the tropics, but intermodel variability is quite large. The regional CO responses to emissions changes are robust across models, however. These range from decreases of 10–20 ppbv over much of the industrialized NH for the CLE scenario to CO increases worldwide and year-round under A2, with the largest changes over central Africa (20–30 ppbv), southern Brazil (20–35 ppbv) and south and east Asia (30–70 ppbv). The trajectory of future emissions thus has the potential to profoundly affect air quality over most of the world’s populated areas.
Singh, H. B., W. H. Brune, J. H. Crawford, D. J. Jacob, and P. B. Russell (2006), Overview of the summer 2004 Intercontinental Chemical Transport Experiment–North America (INTEX-A), Journal of Geophysical Research: Atmospheres, 111(D24), n/a–n/a, doi:10.1029/2006JD007905.
The INTEX-A field mission was conducted in the summer of 2004 (1 July to 15 August 2004) over North America (NA) and the Atlantic in cooperation with multiple national and international partners as part of a consortium called ICARTT. The main goals of INTEX-A were to (1) characterize the composition of the troposphere over NA, (2) characterize the outflow of pollution from NA and determine its chemical evolution during transatlantic transport, (3) validate satellite observations of tropospheric composition, (4) quantitatively relate atmospheric concentrations of gases and aerosols with their sources and sinks, and (5) investigate aerosol properties and their radiative effects. INTEX-A primarily relied on instrumented DC-8 and J-31 aircraft platforms to achieve its objectives. The DC-8 was equipped to measure detailed gas and aerosol composition and provided sufficient range and altitude capability to coordinate activities with distant partners and to sample the entire midlatitude troposphere. The J-31 was specifically focused on radiative effects of clouds and aerosols and operated largely in the Gulf of Maine. Satellite products along with meteorological and 3-D chemical transport model forecasts were integrated into the flight planning process. Intercomparisons were performed to quantify the accuracy of data and to create a unified data set. Satellite validation activities principally focused on Terra (MOPITT, MODIS, and MISR), Aqua (AIRS and MODIS) and Envisat (SCIAMACHY) to validate observations of CO, NO2, HCHO, H2O, and aerosol. Persistent fires in Alaska and NW Canada offered opportunities to quantify emissions from fires and study the transport and evolution of biomass burning plumes. Contrary to expectations, several pollution plumes of Asian origin, frequently mixed with stratospheric air, were sampled over NA. Quasi-Lagrangian sampling was successfully carried out to study chemical aging of plumes during transport over the Atlantic. Lightning NOx source was found to be far larger than anticipated and provided a major source of error in model simulations. The composition of the upper troposphere was significantly perturbed by influences from surface pollution and lightning. Drawdown of CO2 was characterized over NA and its atmospheric abundance related to terrestrial sources and sinks. INTEX-A observations provide a comprehensive data set to test models and evaluate major pathways of pollution transport over NA and the Atlantic. This overview provides a context within which the present and future INTEX-A/ICARTT publications can be understood.
Stavrakou, T., and J.-F. Müller (2006), Grid-based versus big region approach for inverting CO emissions using Measurement of Pollution in the Troposphere (MOPITT) data, Journal of Geophysical Research (Atmospheres), 111(d10), 15304, doi:10.1029/2005JD006896.
The CO columns retrieved by the Measurement of Pollution in the Troposphere (MOPITT) satellite instrument between May 2000 and April 2001 are used together with the Intermediate Model for the Annual and Global Evolution of Species (IMAGES) global chemistry transport model and its adjoint to provide top-down estimates for anthropogenic, biomass burning, and biogenic CO emissions on the global scale, as well as for the biogenic volatile organic compounds (VOC) fluxes, whose oxidation constitutes a major indirect CO source. For this purpose, the big region and grid-based Bayesian inversion methods are presented and compared. In the former setup, the monthly emissions over large geographical regions are quantified. In the grid-based setup, the fluxes are optimized at the spatial resolution of the model and on a monthly basis. Source-specific spatiotemporal correlations among errors on the prior emissions are introduced in order to better constrain the inversion problem. Both inversion techniques bring the model columns much closer to the measurements at all latitudes, but the grid-based analysis achieves a higher reduction of the overall model/data bias. Further comparisons with observed mixing ratios at NOAA Climate Monitoring and Diagnostics Laboratory and Global Atmosphere Watch sites, as well as with airborne measurements are also presented. The inferred emission estimates are weakly dependent on the prior errors and correlations. Our best estimate for the global CO source amounts to 2900 Tg CO/yr in both inversion approaches, about 5% higher than the prior. The global anthropogenic emission estimate is 18% larger than the prior, with the biggest increase for east Asia and a substantial decrease in south Asia. The vegetation fire emission estimates decrease as well, from the prior 467 Tg CO/yr to 450 Tg CO/yr in the grid-based solution and 434 Tg CO/yr in the monthly big region setup, mainly due to a significant reduction of African savanna fire emissions. The biogenic CO/VOC flux estimates are found to be enhanced by about 15% on the global scale. The most significant error reductions concern the biogenic emissions in the tropics, the Asian anthropogenic emissions, and the vegetation fire source over Africa. Our inversion results are further compared with previously reported emission estimates.
Tie, X., G. P. Brasseur, C. Zhao, C. Granier, S. Massie, Y. Qin, P. Wang, G. Wang, P. Yang, and A. Richter (2006), Chemical characterization of air pollution in Eastern China and the Eastern United States, Atmospheric Environment, 40(14), 2607–2625, doi:10.1016/j.atmosenv.2005.11.059.
Satellite data (MODIS, GOME, and MOPITT) together with a chemical transport global model of the atmosphere (MOZART-2) are used to characterize air pollution in Eastern China and the Eastern US to assess the differences between the photochemical conditions in these two regions. Observations show that aerosol concentrations (both fine (radius&lt;0.5 μm) and coarse modes (radius&gt;0.5 μm)) are higher in Eastern China than in the Eastern US. The NOx concentrations in both regions are substantially higher than in remote regions such as over the oceans (150 compared to 5 (1014 # cm−2) over the Pacific Ocean). The CO concentrations are high in both urbanized areas (30 compared to 10 (1017 # cm−2) over the Pacific Ocean). However, the concentrations of non-methane hydrocarbons from both anthropogenic and biogenic sources are considerably lower in Eastern China than in the Eastern US. As a result, the rate of photochemical ozone production and ozone concentrations during summer is significantly lower in Eastern China (daily averaged concentrations of 40–50 ppbv in summer) than in the Eastern US (daily averaged values of 60–70 ppbv). The analysis also shows that in Eastern China, the O3 production is mainly due to the oxidation of carbon monoxide (54% of total O3 production), while, in the Eastern US, the O3 production is attributed primarily to the oxidation of reactive hydrocarbons (68% of total O3 production). The results also indicate that biogenic emissions of hydrocarbons contribute substantially to the production of O3 in the Eastern US. The O3 production due to the oxidation of biogenic hydrocarbons represents approximately one third of total O3 photochemical production in this region. Measurements of surface ozone in the Eastern US and Eastern China seem to support that the summer ozone production is lower in Eastern China than in the Eastern US. However, additional surface measurements, especially of reactive hydrocarbons and ozone are needed in Eastern China in order to improve the present analysis and to confirm our current conclusions. A sensitivity study shows that with increase in anthropogenic emissions of HCs, the surface ozone concentrations significantly increase in Eastern China, indicating that the increase in the emissions of HCs plays an important role for the enhancement in surface ozone in this region.
Wang, T., H. L. A. Wong, J. Tang, A. Ding, W. S. Wu, and X. C. Zhang (2006), On the origin of surface ozone and reactive nitrogen observed at a remote mountain site in the northeastern Qinghai-Tibetan Plateau, western China, Journal of Geophysical Research: Atmospheres, 111(D8), n/a–n/a, doi:10.1029/2005JD006527.
Measurements of surface ozone (O3), carbon monoxide (CO), nitric oxide (NO), and total reactive nitrogen (NOy) were made, in conjunction with other trace gases and fine aerosols, at Mount Waliguan (WLG, 36.28°N, 100.90°E, 3816 m above sea level) in the late spring and summer of 2003 in order to better understand the source(s) of ozone and other chemically active gases over the remote highlands of western China. The average mixing ratio (plus or minus standard deviation) was 58 (±9) ppbv for O3, 155 (±41) ppbv for CO, and 3.83 (±1.46) ppbv for NOy in the spring phase, compared to a summer average value of 54 (±11) ppbv for O3, 125 (±36) ppbv for CO, and 3.60 (±1.13) ppbv for NOy. The daytime (0800–1759 local time) average NO mixing ratios were 72 (±79) pptv and 47 (±32) pptv in the spring and summer, respectively. The ozone mixing ratios exhibited a minimum in late morning, while CO (and NOy in spring) showed enhanced concentrations at night. The latter is in contrast to the diurnal behaviors observed in many remote mountain sites. Analysis of 10-day back trajectories using output from Fifth-Generation National Center for Atmospheric Research/Penn State University Mesoscale Model (MM5) simulations shows that air masses from the remote western regions contained the lowest level of CO (121–129 ppbv) but had the highest O3 (60 ppbv), compared to the other three air mass groups that were impacted by anthropogenic emissions in eastern/southern China and in the Indian subcontinent. Ozone correlated negatively with CO (and water vapor content), particularly during summer in air originating in the west, suggesting that the high-ozone events were mostly derived from the downward transport of the upper tropospheric air and not from anthropogenic pollution. An examination of in situ chemical measurements (CO-NOy correlation, ethyne/propane, and benzene/propane) as well as Measurements of Pollution in the Troposphere (MOPITT) and Moderate-Resolution Imaging Spectroradiometer (MODIS) remote-sensing data revealed some impacts from forest fires in central Asia in the late spring of 2003 on the background concentrations of trace gases over western China. While the O3 and CO levels at WLG are comparable to those at remote continental sites in Europe and North America, the NOy concentrations were substantially higher at WLG. The possible reasons for the abnormally high NOy levels are discussed. While more studies are needed to pin down these sources/causes, including a possible contribution from long-range transport, we believe that microbial processes in soils and animal wastes associated with animal grazing were an important cause of the elevated NOy. The observed daytime NO concentrations imply a net photochemical production of O3 at WLG, suggesting a positive contribution of photochemistry to the ozone budget.
Yumimoto, K., and I. Uno (2006), Adjoint inverse modeling of CO emissions over Eastern Asia using four-dimensional variational data assimilation, Atmospheric Environment, 40(35), 6836–6845, doi:10.1016/j.atmosenv.2006.05.042.
We developed a four-dimensional variational (4DVAR) data assimilation system for a regional chemical transport model (CTM). In this study, we applied it to inverse modeling of CO emissions in the eastern Asia during April 2001 and demonstrated the feasibility of our assimilation system. Three ground-based observations were used for data assimilation. Assimilated results showed better agreement with observations; they reduced the RMS difference by 16–27%. Observations obtained on board the R/V Ronald H. Brown were used for independent validation of the assimilated results. The CO emissions over industrialized east central China between Shanghai and Beijing were increased markedly by the assimilation. The results show that the annual anthropogenic (fossil and biofuel combustion) CO emissions over China are 147 Tg. Sensitivity analyses using the adjoint model indicate that the high CO concentration measured on 17 April at Rishiri, Japan (which the assimilation was unable to reproduce) originated in Russia or had traveled from outside the Asian region (e.g. Europe).
Zhao, C., X. Tie, G. Wang, Y. Qin, and P. Wang (2006), Analysis of Air Quality in Eastern China and its Interaction with Other Regions of the World, J Atmos Chem, 55(3), 189–204, doi:10.1007/s10874-006-9022-1.
In this study, we used satellite data (GOME and MOPITT) together with a global chemical-transport-model of atmosphere (MOZART-2) to characterize the chemical/aerosol composition over eastern China. We then estimated the effects of local emissions in China on the chemical budgets in other regions of the world. Likewise, we also investigated the effects of air pollution from other regions on the chemical budget over eastern China. The study shows that the column CO and NO x concentrations are also high in eastern China. The high CO and NO x concentrations produce modest levels of O3 concentrations during summer (about 40 to 50 ppbv) and very low O3 during winter (about 10 to 20 ppbv) in eastern China. The calculated NO2 column is fairly consistent from the GOME measurement. The calculated CO column is underestimated from the MOPITT measurement. One of the reasons of the underestimation of the predicted CO is due to a fact that the CO emissions were taken without considering the rapid increase of emissions from 1990 to 2000. The calculated surface O3 is consistent with the measured values, with strong seasonal variations. However, the measurement is very limited, and more measurements in eastern China will be needed. The column NO2 has a very strong seasonal variation in eastern China, with the highest concentrations during winter and the lowest concentrations during summer. The cause of this seasonal variability is mainly due to the seasonal changes in the chemical loss of NO x , which is very high in summer and very low during winter. The effects of the local emissions in China and long-range transport from other regions on the chemical distributions in eastern China are studied. The results show that NO x concentrations in eastern China are mostly caused by the local emissions in China, especially during the winter. The CO concentration over eastern China is from both the local emissions (30% to 40%) and the transport from other regions. Likewise, the CO emissions in China have an important effect on the other regions of the world, but the effect is limited in the northern hemisphere. The local emissions in China also have an important effect on surface O3 concentrations. During winter, the local emissions reduce the surface O3 concentrations by 30 to 50%. During summer, the local emissions produce about 50 to 70% of the O3 concentration in eastern China.

2005

Buchwitz, M., R. de Beek, S. Noël, J. P. Burrows, H. Bovensmann, H. Bremer, P. Bergamaschi, S. Körner, and M. Heimann (2005), Carbon monoxide, methane and carbon dioxide columns retrieved from SCIAMACHY by WFM-DOAS: year 2003 initial data set, Atmos. Chem. Phys., 5(12), 3313–3329, doi:10.5194/acp-5-3313-2005.
The near-infrared nadir spectra measured by SCIAMACHY on-board ENVISAT contain information on the vertical columns of important atmospheric trace gases such as carbon monoxide (CO), methane (CH4), and carbon dioxide (CO2). The scientific algorithm WFM-DOAS has been used to retrieve this information. For CH4 and CO2 also column averaged mixing ratios (XCH4 and XCO2) have been determined by simultaneous measurements of the dry air mass. All available spectra of the year 2003 have been processed. We describe the algorithm versions used to generate the data (v0.4; for methane also v0.41) and show comparisons of monthly averaged data over land with global measurements (CO from MOPITT) and models (for CH4 and CO2). We show that elevated concentrations of CO resulting from biomass burning have been detected in reasonable agreement with MOPITT. The measured XCH4 is enhanced over India, south-east Asia, and central Africa in September/October 2003 in line with model simulations, where they result from surface sources of methane such as rice fields and wetlands. The CO2 measurements over the Northern Hemisphere show the lowest mixing ratios around July in qualitative agreement with model simulations indicating that the large scale pattern of CO2 uptake by the growing vegetation can be detected with SCIAMACHY. We also identified potential problems such as a too low inter-hemispheric gradient for CO, a time dependent bias of the methane columns on the order of a few percent, and a few percent too high CO2 over parts of the Sahara.
Choi, Y., Y. Wang, T. Zeng, R. V. Martin, T. P. Kurosu, and K. Chance (2005), Evidence of lightning NOx and convective transport of pollutants in satellite observations over North America, Geophysical Research Letters, 32(2), n/a–n/a, doi:10.1029/2004GL021436.
Column observations of NO2 by GOME and CO by MOPITT over North America and surrounding oceans for April 2000 are analyzed using a regional chemical transport model. Transient enhancements in these measurements due to lightning NOx production or convective transport are examined. Evidence is found for lightning enhancements of NO2 over the continent and western North Atlantic and for convective transport enhancements of CO over the ocean. The two independent satellite measurements show consistent enhancements related to convective events. Model results suggest that the enhancements are particularly large in the lower troposphere due to convective downdrafts of lightning NOx and shallow convection of CO, implying that low-altitude aircraft in situ observations are potentially critical for evaluating the model simulations and validating satellite observations of these transient features.
Dement’ev, B. V., S. A. Reshetnyak, L. A. Shelepin, and V. A. Shcheglov (2005), On the Distribution of an Impurity and Control of its Content in the Atmosphere, J Russ Laser Res, 26(3), 179–197, doi:10.1007/s10946-005-0013-5.
On the basis of a theoretical model of propagation of a gas impurity polluting the atmosphere, formulas are obtained that relate the power of the impurity source with the impurity content when measured by a gas-correlation IR radiometer. The model takes into account transfer of the gas impurity by wind, its diffusion, and vertical motion. Requirements on the sensitivity of instrumentation are analyzed. Estimates of the possibility of remote monitoring of the atmosphere are also made.
Freitas, S. R., K. M. Longo, M. A. F. S. Dias, P. L. S. Dias, R. Chatfield, E. Prins, P. Artaxo, G. A. Grell, and F. S. Recuero (2005), Monitoring the transport of biomass burning emissions in South America, Environ Fluid Mech, 5(1–2), 135–167, doi:10.1007/s10652-005-0243-7.
The atmospheric transport of biomass burning emissions in the South American and African continents is being monitored annually using a numerical simulation of air mass motions; we use a tracer transport capability developed within RAMS (Regional Atmospheric Modeling System) coupled to an emission model. Mass conservation equations are solved for carbon monoxide (CO) and particulate material (PM2.5). Source emissions of trace gases and particles associated with biomass burning activities in tropical forest, savanna and pasture have been parameterized and introduced into the model. The sources are distributed spatially and temporally and assimilated daily using the biomass burning locations detected by remote sensing. Advection effects (at grid scale) and turbulent transport (at sub-grid scale) are provided by the RAMS parameterizations. A sub-grid transport parameterization associated with moist deep and shallow convection, not explicitly resolved by the model due to its low spatial resolution, has also been introduced. Sinks associated with the process of wet and dry removal of aerosol particles and chemical transformation of gases are parameterized and introduced in the mass conservation equation. An operational system has been implemented which produces daily 48-h numerical simulations (including 24-h forecasts) of CO and PM2.5, in addition to traditional meteorological fields. The good prediction skills of the model are demonstrated by comparisons with time series of PM2.5 measured at the surface.
Gloudemans, A. M. S., H. Schrijver, Q. Kleipool, M. M. P. van den Broek, A. G. Straume, G. Lichtenberg, R. M. van Hees, I. Aben, and J. F. Meirink (2005), The impact of SCIAMACHY near-infrared instrument calibration on CH4 and CO total columns, Atmos. Chem. Phys., 5(9), 2369–2383, doi:10.5194/acp-5-2369-2005.
The near-infrared spectra measured with the SCIAMACHY instrument on board the ENVISAT satellite suffer from several instrument calibration problems. The effects of three important instrument calibration issues on the retrieved methane (CH4) and carbon monoxide (CO) total columns have been investigated: the effects of the growing ice layer on the near-infrared detectors, the effects of the orbital variation of the instrument dark signal, and the effects of the dead/bad detector pixels. Corrections for each of these instrument calibration issues have been defined. The retrieved CH4 and CO total columns including these corrections show good agreement with CO measurements from the MOPITT satellite instrument and with CH4 model calculations by the chemistry transport model TM3. Using a systematic approach, it is shown that all three instrument calibration issues have a significant effect on the retrieved CH4 and CO total columns. However, the impact on the CH4 total columns is more pronounced than for CO, because of its smaller variability. Results for three different wavelength ranges are compared and show good agreement. The growing ice layer and the orbital variation of the dark signal show a systematic, but time-dependent effect on the retrieved CH4 and CO total columns, whereas the effect of the dead/bad pixels is rather unpredictable: some dead pixels show a random effect, some more systematic, and others no effect at all. The importance of accurate corrections for each of these instrument calibration issues is illustrated using examples where inaccurate corrections lead to a wrong interpretation of the results.
Ho, S.-P., D. P. Edwards, J. C. Gille, J. Chen, D. Ziskin, G. L. Francis, M. N. Deeter, and J. R. Drummond (2005), Estimates of 4.7 μm surface emissivity and their impact on the retrieval of tropospheric carbon monoxide by Measurements of Pollution in the Troposphere (MOPITT), Journal of Geophysical Research (Atmospheres), 110(d9), 21308, doi:10.1029/2005JD005946.
Carbon monoxide (CO) is an important tropospheric trace species. The Measurements of Pollution in the Troposphere (MOPITT) instrument uses the 4.7 μm CO band to measure the global CO profile and total column amount in the troposphere from space. In the operational MOPITT CO retrieval algorithm, surface skin temperature (Ts) and emissivity (E) are retrieved simultaneously with the CO profile. However, because both Ts and E are retrieved from the same piece of information from the MOPITT measurements, the accuracy of both variables may be limited, which leads to an increase of uncertainty in the CO retrievals. An accurate specification of the surface skin temperature is required to determine surface emissivity and vice versa. In this study, a method is developed which uses Ts from the Moderate Resolution Imaging Spectroradiometer (MODIS) and MOPITT radiances to derive an improved 4.7 μm surface emissivity estimate (E) for use in retrievals by the MOPITT instrument. Monthly mean 4.7 μm surface emissivity maps for 1 year are generated and used as the a priori E in the MOPITT Ts and CO retrieval algorithm. We show that the geographical distribution of the 4.7 μm emissivity is very consistent with MODIS normalized difference vegetation index distribution, which is strongly tied to the surface emissivity. This a priori E has a much smaller standard deviation than values currently used in the MOPITT retrieval. As a result, more radiance information tends to be used in the MOPITT Ts and CO retrievals. By using the improved a priori E over the land, the information content of MOPITT radiances increases 15% at night and 5% during the day relative to the current version MOPITT data products. The difference between day and night information content (or diurnal difference) decreases from 0.3 (current version) to 0.21, showing that nighttime retrievals are improved. Over the global ocean the diurnal difference of the MOPITT information content decreases from 0.15 (current version) to 0.06. The differences between the new profile retrievals and those of current profile retrievals are very consistent with their corresponding diurnal and geographical information content distributions. Over the global ocean the new MOPITT CO profile is lower by 3-11% during the night in the lower troposphere. Over the global land the new CO profile is higher by 3.2% in the lower troposphere during the night. The differences between the new profile retrieval and those of current retrieval are small during the day.
Kim, J. H., S. Na, M. J. Newchurch, and R. V. Martin (2005), Tropical tropospheric ozone morphology and seasonality seen in satellite and in situ measurements and model calculations, Journal of Geophysical Research: Atmospheres, 110(D2), n/a–n/a, doi:10.1029/2003JD004332.
An important issue in satellite remote sensing techniques for retrieving tropical tropospheric ozone is understanding the cause of the disagreement between ozone derived from satellite residual-based methods and the precursor distributions seen in both the fire count distribution and the Measurements Of Pollution In The Troposphere (MOPITT) CO distribution over northern tropical Atlantic and Africa in boreal winter and spring. This discrepancy has been called the Northern Atlantic paradox; however, it actually extends eastward all the way to Indonesia. We define the disagreement as the northern tropical paradox. We employ the scan angle method (SAM) to solve the paradox. This algorithm takes advantage of the difference in the Total Ozone Mapping Spectrometer (TOMS) retrieval information between nadir and high viewing angles. The averaging kernel for this difference exhibits a broad maximum centered at ∼5 km in the troposphere and thereby can be used to estimate tropospheric ozone information. The seasonal distribution of tropospheric ozone derived from the SAM algorithm shows remarkably good agreement with fire counts from Along Track Scanning Radiometer (ATSR), CO from MOPITT, TOMS aerosol index, and ozone distribution from the GEOS-CHEM model in four seasons over the tropics. In meridional distribution, all of these products clearly reveal the seasonal oscillation between northern tropical Africa in boreal winter and over southern tropical Africa in boreal summer. The residual-based methods (TOR, CCD, CCP, and modified residual), however, always show the ozone maximum over the southern Atlantic off the coast of southwest Africa. A further comparison with the in situ measurements from the Measurement of Ozone and Water Vapor by Airbus In-Service Aircraft (MOZAIC) campaign at three locations over the northern tropics, Abidjan (5°N, 4°W), Madras (13°N, 80°E), and Bangkok (14°N, 101°E), supports our results. The seasonality of ozone from the SAM and the model, which shows the ozone maximum in boreal summer and the minimum in boreal winter, is in accordance with the MOZAIC measurements. However, the seasonality of the RBMs does not agree with the seasonality of in situ measurements. We conclude that the northern tropical paradox does not actually exist.
Lee, S., G. H. Choi, H. S. Lim, J. H. Lee, K. H. Lee, Y. J. Kim, and J. Kim (2005), Detection of Russian fires using MOPITT and MODIS data, in On the Convergence of Bio-Information-, Environmental-, Energy-, Space- and Nano-Technologies, Pts 1 and 2, vol. 277–279, edited by K. H. Chung, Y. H. Shin, S. N. Park, H. S. Cho, S. A. Yoo, B. J. Min, H. S. Lim, and K. H. Yoo, pp. 816–823.
The great fires were detected through the Moderate Resolution Imaging Spectroradiometer (MODIS) observations over Northeast Asia. The large amount of smoke produced near Lake Baikal was transported to East Asia using high Aerosol Optical Thickness (AOT) as seen through the satellite images. The smoke pollution from the Russian forest fires would sometimes reach Korea through Mongolia and eastern China. In May 2003, a number of large fires blazed through eastern Russian, producing a thick, widespread pall of smoke over much of East Asia. This study focuses on the identification of the carbon monoxide (CO) for MOPITT released from MOPITT primarily into East Asia during the Russian Fires. In the wake of the fires, the 700hPa MOPITT retrieved CO concentrations which reached up to 250ppbv. Smoke aerosol retrieval using a separation technique was also applied to the MODIS data observed in 14-22 May 2003. Large AOT, 2.0 similar to 5.0, was observed over Korea on 20 May 2003 due to the influence of the long range transport of smoke aerosol plume from the Russian Fires.
Li, Q., D. J. Jacob, R. Park, Y. Wang, C. L. Heald, R. Hudman, R. M. Yantosca, R. V. Martin, and M. Evans (2005), North American pollution outflow and the trapping of convectively lifted pollution by upper-level anticyclone, Journal of Geophysical Research: Atmospheres, 110(D10), n/a–n/a, doi:10.1029/2004JD005039.
We examine the major outflow pathways for North American pollution to the Atlantic in summer by conducting a 4-year simulation with the GEOS-CHEM global chemical transport model, including a coupled ozone-aerosol simulation with 1° × 1° horizontal resolution for summer 2000. The outflow is driven principally by cyclones tracking eastward across North America at 45–55°N, every 5 days on average. Anthropogenic and fire effluents from western North America are mostly transported north and east, eventually merging with the eastern U.S. pollution outflow to the Atlantic. A semipermanent upper-level anticyclone traps the convective outflow and allows it to age in the upper troposphere over the United States for several days. Rapid ozone production takes place in this outflow, driven in part by anthropogenic and lightning NOx and in part by HOx radicals produced from convectively lifted CH2O that originates from biogenic isoprene. This mechanism could explain ozonesonde observations of elevated ozone in the upper troposphere over the southeastern United States. Asian and European pollution influences in the North American outflow to the Atlantic are found to be dispersed into the background and do not generate distinct plumes. Satellite observations of CO columns from MOPITT and of aerosol optical depths (AODs) from MODIS provide useful mapping of outflow events, despite their restriction to clear-sky scenes.
Liu, J., J. R. Drummond, Q. Li, J. C. Gille, and D. C. Ziskin (2005), Satellite mapping of CO emission from forest fires in Northwest America using MOPITT measurements, Remote Sensing of Environment, 95(4), 502–516, doi:10.1016/j.rse.2005.01.009.
We present a study on MOPITT (Measurements Of Pollution In The Troposphere) detection of CO emission from large forest fires in the year 2000 in the northwest United States. Fire data used are from the space-borne Advanced Very High Resolution Radiometer (AVHRR) at 1-km resolution. The study shows that MOPITT can reliably detect CO plumes from forest fires whenever there are &gt;30 AVHRR hotspots in a 0.25° × 0.25° grid, which is comparable to the pixel area of MOPITT in the region. The spatial CO pattern during the fire events is found to be consistent with the location and density of AVHRR hotspots and wind direction. While the increase of CO abundance inside the study area is closely correlated to the AVHRR-derived hotspot number in general (R &gt; 0.75), the non-linearity of fire emission with fuel consumption is also observed. MOPITT can also capture the temporal variation in CO emission from forest fires through 3-day composites so it may offer an opportunity to enhance our knowledge of temporal fire emission over large areas. The CO emission is quantitatively estimated with a one-box model. The result is compared with a bottom-up approach using surface data including burnt area, biomass density, and fire emission factors. If mean emission factors for the region are used, the bottom-up approach results in total emission estimates which are 10%–50% lower than the MOPITT-based estimate. In spite of the limitations and uncertainties addressed in this study, MOPITT data may provide a useful constraint on uncertain ground-based fire emission estimates.
Pfister, G., J. C. Gille, D. Ziskin, G. Francis, D. P. Edwards, M. N. Deeter, and E. Abbott (2005a), Effects of a Spectral Surface Reflectance on Measurements of Backscattered Solar Radiation: Application to the MOPITT Methane Retrieval, Journal of Atmospheric and Oceanic Technology, 22(5), 566–574, doi:10.1175/JTECH1721.1.
The amount of solar radiation emerging from the top of the atmosphere is strongly influenced by the reflectance of the underlying surface. For this reason, some information about the magnitude and the spectral variability of the surface reflectance typically has to be included in the retrieval of atmospheric parameters from reflected solar radiation measurements. Sufficient information about the surface reflectance properties is rarely available, and the integration of this effect in the retrieval might turn out to be a challenge, especially for broadband instruments. In this paper the focus is on the Measurements of Pollution in the Troposphere (MOPITT) remote sensing instrument. Theoretical studies are performed to investigate how a spectrally varying surface reflectance might impact the retrieval of the total column amount of methane from MOPITT radiance measurements, and the current findings are compared to observed biases. However, the findings present herein might be valuable and applicable for other remote sensing instruments that are sensitive to the amount of solar radiation reflected from the earth’s surface.
Pfister, G., P. G. Hess, L. K. Emmons, J.-F. Lamarque, C. Wiedinmyer, D. P. Edwards, G. Pétron, J. C. Gille, and G. W. Sachse (2005b), Quantifying CO emissions from the 2004 Alaskan wildfires using MOPITT CO data, Geophysical Research Letters, 32, 11809, doi:10.1029/2005GL022995.
We present an inverse model analysis to quantify the emissions of wildfires in Alaska and Canada in the summer of 2004 using carbon monoxide (CO) data from the Measurements of Pollution in the Troposphere (MOPITT) remote sensing instrument together with the chemistry transport model MOZART (Model for Ozone and Related Chemical Tracers). We use data assimilation outside the region of the fires to optimally constrain the CO background level and the transport into that region. Inverse modeling is applied locally to quantify the fire emissions. Our a posteriori estimate of the wildfire emissions gives a total of 30 +/- 5 Tg CO emitted during June-August 2004 which is of comparable order to the anthropogenic emissions for the continental US. The simulated CO fields have been evaluated by comparison with MOPITT and independent aircraft data.
Shindell, D. T., G. Faluvegi, and L. K. Emmons (2005), Inferring carbon monoxide pollution changes from space-based observations, Journal of Geophysical Research: Atmospheres, 110(D23), n/a–n/a, doi:10.1029/2005JD006132.
We compare space-based measurements of carbon monoxide (CO) during April 1994 and October 1984 and 1994 from the early MAPS instrument with those during 2000–2004 from the MOPITT instrument. We show that a three-dimensional global composition model can be used to account for differences in retrieval sensitivity between the two instruments and between the different years of MOPITT data. This allows direct comparison of CO amounts over most of the globe at different times. These types of changes in short-lived constituents cannot be assessed with local measurements. Though the existing space-based data are too sparse both temporally and geographically to allow trend estimates, we find substantial variations in midtropospheric CO between the different years in many continental-scale regions. During April, average CO is ∼12–18 ppbv (∼10–20%) greater during 2000–2004 than during 1994 over North America, southeast Asia and North Africa though the global mean value is nearly the same. During October 1994, observations show CO enhancements of 15–20 ppbv relative to 1984 or 2000–2004 over South America and a similar, though slightly smaller (9–19 ppbv), enhancement globally. Southeast Asia, Europe and North America all show similar October CO levels in 1994 and 2000–2004, with both times showing substantially more pollution (13–29 ppbv) than 1984. Variations over Europe and Africa are consistent in both seasons, while changes elsewhere are not. Changes over southeast Asia and North Africa are substantially in excess of interannual variability, while those over North and South America and southern Africa are only marginally so. Model sensitivity studies examining the response to changes in emissions indicate probable causes of the CO changes over different regions. Over southeast Asia and North America, CO is most sensitive to industrial and biomass burning emissions, implying that changes in these sources likely account for the 13–29 ppbv increases seen there between 2000–2004 and earlier years. Over North Africa, CO is strongly influenced by numerous sources as well as meteorology, precluding attribution of increases to particular factors. Over South America and southern Africa, variations in both biomass burning and isoprene emissions likely contributed to the ∼10–20 ppbv changes.
Straume, A. G., H. Schrijver, A. M. S. Gloudemans, S. Houweling, I. Aben, A. N. Maurellis, A. T. J. de Laat, Q. Kleipool, G. Lichtenberg, R. van Hees, J. F. Meirink, and M. Krol (2005), The global variation of CH4 and CO as seen by SCIAMACHY, Advances in Space Research, 36(5), 821–827, doi:10.1016/j.asr.2005.03.027.
The methane (CH4) and carbon monoxide (CO) total columns retrieved from SCIAMACHY’s near-infrared channel 8 have been compared to satellite measurements by the MOPITT instrument and chemistry transport model calculations (TM3). Results from the SRON retrieval algorithm IMLM (v5.1) are presented here for the month of February 2004. First results show that these monthly averaged data are in good agreement with TM3 model calculations and the measurements by the MOPITT instrument.
Velazco, V., J. Notholt, T. Warneke, M. Lawrence, H. Bremer, J. Drummond, A. Schulz, J. Krieg, and O. Schrems (2005), Latitude and altitude variability of carbon monoxide in the Atlantic detected from ship-borne Fourier transform spectrometry, model, and satellite data, Journal of Geophysical Research: Atmospheres, 110(D9), n/a–n/a, doi:10.1029/2004JD005351.
Carbon monoxide (CO) volume mixing ratio (VMR) profiles have been retrieved from ship-borne solar absorption spectra recorded in the Atlantic between 80°N and 70°S. CO profiles can be retrieved up to 30 km with a maximum altitude resolution of 4 km for a few layers. CO enhancements due to biomass burning have been detected. Recurring enhancements of CO were detected in the upper troposphere (10–15 km) in the equatorial regions and in the southern Atlantic (20°S–30°S). These enhancements could be traced back to African biomass burning sources as well as sources as far as South America. Similar results are observed in CO measurements from space by the Measurements of Pollution in the Troposphere (MOPITT) instrument. However, some enhancements in the upper troposphere especially above the source regions are difficult to distinguish from the MOPITT data. Results from the Model of Atmospheric Transport and Chemistry from the Max Planck Institute for Chemistry (MATCH-MPIC) show good agreement with the FTIR results. An analysis of the model data allows the quantification of the contributions of different sources such as biomass burning, fossil fuel combustion, and oxidation of methane (CH4) and nonmethane hydrocarbons (NMHC).
Yurganov, L. N., P. Duchatelet, A. V. Dzhola, D. P. Edwards, F. Hase, I. Kramer, E. Mahieu, J. Mellqvist, J. Notholt, P. C. Novelli, A. Rockmann, H. E. Scheel, M. Schneider, A. Schulz, A. Strandberg, R. Sussmann, H. Tanimoto, V. Velazco, J. R. Drummond, and J. C. Gille (2005), Increased Northern Hemispheric carbon monoxide burden in the troposphere in 2002 and 2003 detected from the ground and from space, Atmos. Chem. Phys., 5(2), 563–573, doi:10.5194/acp-5-563-2005.
Carbon monoxide total column amounts in the atmosphere have been measured in the High Northern Hemisphere (30°-90° N, HNH) between January 2002 and December 2003 using infrared spectrometers of high and moderate resolution and the Sun as a light source. They were compared to ground-level CO mixing ratios and to total column amounts measured from space by the Terra/MOPITT instrument. All these data reveal increased CO abundances in 2002-2003 in comparison to the unperturbed 2000-2001 period. Maximum anomalies were observed in September 2002 and August 2003. Using a simple two-box model, the corresponding annual CO emission anomalies (referenced to 2000-2001 period) have been found equal to 95Tg in 2002 and 130Tg in 2003, thus close to those for 1996 and 1998. A good correlation with hot spots detected by a satellite radiometer allows one to assume strong boreal forest fires, occurred mainly in Russia, as a source of the increased CO burdens.

2004

Allen, D., K. Pickering, and M. Fox-Rabinovitz (2004), Evaluation of pollutant outflow and CO sources during TRACE-P using model-calculated, aircraft-based, and Measurements of Pollution in the Troposphere (MOPITT)-derived CO concentrations, Journal of Geophysical Research: Atmospheres, 109(D15), n/a–n/a, doi:10.1029/2003JD004250.
Outflow of CO from Asia during March 2001 is evaluated using data from the Transport and Chemical Evolution over the Pacific (TRACE-P) mission and the Measurements of Pollution in the Troposphere (MOPITT) instrument in conjunction with model-calculated CO from the University of Maryland chemistry and transport model (UMD CTM). Comparison of model-calculated CO with aircraft measurements indicates that temporal and spatial variations in CO are well captured by the model (mean correlation coefficient of 0.78); however, model-calculated mixing ratios are lower than observed especially for pressures >850 hPa where negative biases of ∼60 ppbv were seen. Regression analysis is used to optimize the magnitudes of the bottom-up TRACE-P Asian fossil fuel (FF), biofuel (BF), and biomass burning (BB) CO emission inventories. Resulting Asian scaling factors are 1.59 ± 0.34 for FF + BF emissions and 0.47 ± 0.46 for BB emissions. Resulting FF + BF emissions are 27.7 ± 6.1 Tg for March 2001 (301 ± 67 Tg for an entire year). Resulting BB emissions for March 2001 are 8.5 ± 8.3 Tg. These results are consistent with recent inverse modeling studies. Scaling factors are lowest (highest) for experiments that assume a high (low) CO yield for the oxidation of anthropogenic and natural hydrocarbons and for experiments that use (do not use) an aerosol-modified OH distribution. Comparison of model-calculated CO with MOPITT measurements supports the results from our regression analysis. Without exception, mean March 2001 model-calculated CO profiles in the TRACE-P region from a simulation with adjusted CO sources are within a standard deviation of mean March 2001 MOPITT-sampled profiles.
Arellano, A. F., P. S. Kasibhatla, L. Giglio, G. R. van der Werf, and J. T. Randerson (2004), Top-down estimates of global CO sources using MOPITT measurements, Geophysical Research Letters, 31(1), doi:10.1029/2003GL018609. [online] Available from: http://onlinelibrary.wiley.com/doi/10.1029/2003GL018609/abstract .
We present a synthesis inversion of CO emissions from various geographical regions and for various source categories for the year 2000 using CO retrievals from the MOPITT (Measurements of Pollution in the Troposphere) instrument. We find a large discrepancy between our top-down estimates and recent bottom-up estimates of CO emissions from fossil fuel/biofuel (FFBF) use in Asia. A key conclusion of this study is that CO emissions in East Asia (EAS) are about a factor of 1.8–2 higher than recent bottom-up estimates.
Bremer, H., J. Kar, J. R. Drummond, F. Nichitu, J. Zou, J. Liu, J. C. Gille, M. N. Deeter, G. Francis, D. Ziskin, and J. Warner (2004), Spatial and temporal variation of MOPITT CO in Africa and South America: A comparison with SHADOZ ozone and MODIS aerosol, Journal of Geophysical Research: Atmospheres, 109(D12), n/a–n/a, doi:10.1029/2003JD004234.
Carbon monoxide (CO) measurements from the Measurements of Pollution in the Troposphere (MOPITT) experiment are used to explore the correlation between biomass burning and ozone profiles at six tropical stations namely Reunion, Irene, Natal, Ascension, San Cristobal, and Paramaribo. Distinct seasonal patterns of CO at each station indicate the strong influence of African and South American biomass burning. All stations show enhanced CO columns during September–November (SON) corresponding to austral burning. Furthermore, the effects of Sahelian burning can be seen at Natal and Ascension. Similarly, the signature of northern Amazonian fires can be observed at San Cristobal. The CO variations are generally similar to the variations of aerosol optical depth (AOD) retrieved contemporaneously from Moderate Resolution Imaging Spectroradiometer (MODIS) at most stations, with notable differences at Irene, San Cristobal, and Paramaribo. Tropospheric ozone from Southern Hemisphere Additional Ozonesonde (SHADOZ) ozonesonde measurements at all stations show elevated levels, corresponding to the CO enhancements in SON months. However, there are several instances of ozone enhancements unaccompanied by any CO increase. This might indicate that sources other than biomass burning such as stratospheric tropospheric exchange (STE) or lightning related NOx may be operative. At San Cristobal, strong CO enhancements during March–April are not accompanied by any significant change in ozone.
Buchwitz, M., R. de Beek, K. Bramstedt, S. Noël, H. Bovensmann, and J. P. Burrows (2004), Global carbon monoxide as retrieved from SCIAMACHY by WFM-DOAS, Atmos. Chem. Phys., 4(7), 1945–1960, doi:10.5194/acp-4-1945-2004.
First results concerning the retrieval of tropospheric carbon monoxide (CO) from satellite solar backscatter radiance measurements in the near-infrared spectral region (∼2.3µm) are presented. The Weighting Function Modified (WFM) DOAS retrieval algorithm has been used to retrieve vertical columns of CO from SCIAMACHY/ENVISAT nadir spectra. We present detailed results for three days from the time periode January to October 2003 selected to have good overlap with the daytime CO measurements of MOPITT onboard EOS Terra. Because the WFM-DOAS Version 0.4 CO columns presented in this paper are scaled by a constant factor of 0.5 to compensate for an obvious overestimation we focus on the variability of the retrieved columns rather than on their absolute values. It is shown that plumes of CO resulting from, e.g. biomass burning in Africa, are detectable with single overpass SCIAMACHY data. Globally, the SCIAMACHY CO columns are in reasonable agreement with the Version 3 CO column data product of MOPITT. For example, for measurements over land, where the quality of the data is typically better than over ocean due to higher surface reflectivity, the standard deviation of the difference with respect to MOPITT is in the range 0.4-0.6x1018 molecules/cm2 and the linear correlation coefficient is between 0.4 and 0.7. The level of agreement between the data of both sensors depends on time and location but is typically within 30% for most latitudes. In the southern hemisphere outside Antarctica SCIAMACHY tends to give systematically higher values than MOPITT. More studies are needed to find out what the reasons for the observed differences with respect to MOPITT are and how the algorithm can be modified to improve the quality of the CO columns as retrieved from SCIAMACHY.
Crawford, J. H., C. L. Heald, H. E. Fuelberg, D. M. Morse, G. W. Sachse, L. K. Emmons, J. C. Gille, D. P. Edward, M. N. Deeter, G. Chen, J. R. Olson, V. S. Connors, C. Kittaka, and A. J. Hamlin (2004), Relationship between Measurements of Pollution in the Troposphere (MOPITT) and in situ observations of CO based on a large-scale feature sampled during TRACE-P, Journal of Geophysical Research (Atmospheres), 109(d18), 15, doi:10.1029/2003JD004308.
During Transport and Chemical Evolution over the Pacific (TRACE-P), there were several opportunities to perform in situ sampling coincident with overpasses of the Measurements of Pollution in the Troposphere (MOPITT) instrument on board the EOS Terra satellite. This sampling consisted of in situ vertical profiles of CO by NASA’s DC-8 aircraft intended to provide data useful for validating MOPITT observations of CO column. One particular profile conducted over the central North Pacific revealed a layer of pollution characterized by CO mixing ratios more than double background values. Sampling of the surrounding region by both the NASA DC-8 and P-3B aircraft showed this layer to have a considerable geographic extent, at least 25° longitude (∼2500 km) and 4° latitude (∼400 km). Using back trajectory analysis, this polluted layer is followed back in time and compared with four consecutive MOPITT overpasses. MOPITT observations during these four overpasses agree well with the location of the layer as inferred by the trajectories; however, the detected CO column amount increases backward in time by just over 20%. Further analysis shows that the majority of this change in detected column abundance is consistent with two factors: (1) changes in the thickness of the polluted layer over time (9 +/- 3%) and (2) changes in retrieved column abundance due to the altitude of the layer (7 +/- 3%). This demonstrates that there are both real and artificial sources of variability that must be understood before MOPITT observations can be quantitatively useful. An unexpected finding was the difference in the variance of MOPITT observations depending on whether observations were taken under daylight or nighttime conditions. The variance in daytime observations of the polluted layer was approximately double that for nighttime data. The results of this analysis indicate that targeted in situ sampling of large-scale pollution events can provide insight leading to more realistic interpretation of MOPITT observations. Strategies for sampling such events repeatedly during their evolution could also provide more interesting opportunities for validation.
Deeter, M. N., L. K. Emmons, G. L. Francis, D. P. Edwards, J. C. Gille, J. X. Warner, B. Khattatov, D. Ziskin, J.-F. Lamarque, S.-P. Ho, V. Yudin, J.-L. Attie, D. Packman, J. Chen, D. Mao, J. R. Drummond, P. Novelli, and G. Sachse (2004a), Evaluation of operational radiances for the Measurements of Pollution in the Troposphere (MOPITT) instrument CO thermal band channels, Journal of Geophysical Research: Atmospheres, 109(D3), n/a–n/a, doi:10.1029/2003JD003970.
The ability of operational radiative transfer models to accurately predict remote sensing instrument observations (e.g., calibrated radiances) over a wide variety of geophysical situations is critical to the performance of trace gas retrieval algorithms. As part of the validation of the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument, we present a technique for comparing operational calibrated thermal band (4.7 μm) Earth-view MOPITT radiances with corresponding values calculated using the MOPITT operational radiative transfer model. In situ carbon monoxide (CO) profiles sampled from aircraft in coordination with MOPITT overpasses serve as the foundation for MOPITT validation. Characteristics of radiance errors due to in situ sampling characteristics, CO temporal and spatial variability, and surface emissivity are discussed. Results indicate that radiance biases for most of the MOPITT thermal channel radiances are typically on the order of 1%. Observed radiance biases are largest and most variable for the pressure modulation cell difference-signal radiances, probably because of the lack of in situ data in the upper troposphere and lower stratosphere.
Deeter, M. N., L. K. Emmons, D. P. Edwards, J. C. Gille, and J. R. Drummond (2004b), Vertical resolution and information content of CO profiles retrieved by MOPITT, Geophysical Research Letters, 31, 15112, doi:10.1029/2004GL020235.
The MOPITT (Measurements of Pollution in the Troposphere) remote sensing instrument monitors the global distribution of carbon monoxide from a polar-orbiting platform. Calculated averaging kernels for operational MOPITT CO profiles indicate the capability of independently retrieving mid- and upper-tropospheric CO. The information content in MOPITT retrievals is objectively quantified through calculation of the Degrees of Freedom for Signal (DFS), which indicates the number of independent pieces of information in the retrieved profile. DFS values larger than 1 (indicating some amount of profile shape information) are common in tropical and midlatitude scenes. The existence of shape information in actual MOPITT retrieved profiles is also verified through (1) a quantitative comparison with in-situ data acquired as part of MOPITT validation and (2) a qualitative comparison with monthly mean rain rate (as an index for convection) in the Tropical Eastern Pacific Ocean.
Edwards, D. P., L. K. Emmons, D. A. Hauglustaine, D. A. Chu, J. C. Gille, Y. J. Kaufman, G. Pétron, L. N. Yurganov, L. Giglio, M. N. Deeter, V. Yudin, D. C. Ziskin, J. Warner, J.-F. Lamarque, G. L. Francis, S. P. Ho, D. Mao, J. Chen, E. I. Grechko, and J. R. Drummond (2004), Observations of carbon monoxide and aerosols from the Terra satellite: Northern Hemisphere variability, Journal of Geophysical Research (Atmospheres), 109(d18), 24202, doi:10.1029/2004JD004727.
Measurements from the Terra satellite launched in December of 1999 provide a global record of the recent interannual variability of tropospheric air quality: carbon monoxide (CO) from the Measurement of Pollution in the Troposphere (MOPITT) instrument and aerosol optical depth (AOD) from the Moderate-Resolution Imaging Spectroradiometer (MODIS). This paper compares and contrasts these data sets with a view to understanding the general features of the overall pollutant loading of the Northern Hemisphere (NH). We present a detailed examination of the seasonal and recent interannual variability of the fine mode AOD and CO column, first considering the variation of the global zonal average for both quantities, and then concentrating on several geographical regions with the aim of isolating different emissions. In a zonal sense, the principal NH sources are related to anthropogenic urban and industrial activity. We show that both the CO and the AOD zonal seasonal variations reflect the atmospheric oxidant concentration, which determines the primary sink of CO and the production of sulfate aerosol. As a consequence, the seasonal cycles are several months out of phase, with perturbations resulting from sporadic wildfire or biomass-burning emissions. In these cases, carbonaceous particles dominate the AOD, and this results in the best correlation with the CO column. Of the 4 years of data available from the Terra satellite, the winter and spring of 2002-2003 showed anomalously high NH pollution compared to the previous years. This was a result of fires in western Russia in the late summer and fall of 2002 and intense fires in the southeast of Russia in the spring and summer of 2003. We examine these events using fire counts from MODIS to indicate the burning regions and investigate how the timing of the fires in relation to atmospheric oxidant concentrations affects the resultant seasonal pollutant loadings. Finally, we trace the emissions from these fires to indicate how intense local pollution sources can impact continental- and global-scale air quality.
Emmons, L. K., M. N. Deeter, J. C. Gille, D. P. Edwards, J.-L. Attié, J. Warner, D. Ziskin, G. Francis, B. Khattatov, V. Yudin, J.-F. Lamarque, S.-P. Ho, D. Mao, J. S. Chen, J. Drummond, P. Novelli, G. Sachse, M. T. Coffey, J. W. Hannigan, C. Gerbig, S. Kawakami, Y. Kondo, N. Takegawa, H. Schlager, J. Baehr, and H. Ziereis (2004), Validation of Measurements of Pollution in the Troposphere (MOPITT) CO retrievals with aircraft in situ profiles, Journal of Geophysical Research: Atmospheres, 109(D3), n/a–n/a, doi:10.1029/2003JD004101.
Validation of the Measurements of Pollution in the Troposphere (MOPITT) retrievals of carbon monoxide (CO) has been performed with a varied set of correlative data. These include in situ observations from a regular program of aircraft observations at five sites ranging from the Arctic to the tropical South Pacific Ocean. Additional in situ profiles are available from several short-term research campaigns situated over North and South America, Africa, and the North and South Pacific Oceans. These correlative measurements are a crucial component of the validation of the retrieved CO profiles and columns from MOPITT. The current validation results indicate good quantitative agreement between MOPITT and in situ profiles, with an average bias less than 20 ppbv at all levels. Comparisons with measurements that were timed to sample profiles coincident with MOPITT overpasses show much less variability in the biases than those made by various groups as part of research field experiments. The validation results vary somewhat with location, as well as a change in the bias between the Phase 1 and Phase 2 retrievals (before and after a change in the instrument configuration due to a cooler failure). During Phase 1, a positive bias is found in the lower troposphere at cleaner locations, such as over the Pacific Ocean, with smaller biases at continental sites. However, the Phase 2 CO retrievals show a negative bias at the Pacific Ocean sites. These validation comparisons provide critical assessments of the retrievals and will be used, in conjunction with ongoing improvements to the retrieval algorithms, to further reduce the retrieval biases in future data versions.
Gros, V., J. Williams, M. G. Lawrence, R. von Kuhlmann, J. van Aardenne, E. Atlas, A. Chuck, D. P. Edwards, V. Stroud, and M. Krol (2004), Tracing the origin and ages of interlaced atmospheric pollution events over the tropical Atlantic Ocean with in situ measurements, satellites, trajectories, emission inventories, and global models, Journal of Geophysical Research: Atmospheres, 109(D22), n/a–n/a, doi:10.1029/2004JD004846.
During a west to east crossing of the tropical Atlantic Ocean in October–November 2002 on R/V Meteor (M55), carbon monoxide (CO) and ozone were continuously monitored, and pressurized air samples were collected and later analyzed in the laboratory for various volatile organic compounds. A sequence of alternating CO and propane rich events were observed over the east Atlantic, the events of enhanced carbon monoxide being out of phase with those observed for propane. A combined study of air mass origin (back trajectories and backward emission sensitivity calculations) and source region distribution comparison (CO satellite data from MOPITT and propane emission data from the EDGAR database) showed that the CO events were due to African biomass burning emissions, whereas the propane events were due to industrial emissions from areas of northern Africa. Both events were associated with elevated ozone. A comparison of the measured concentrations of CO and propane with those simulated by the global Model of Atmospheric Transport and Chemistry-Max Planck Institute for Chemistry (MATCH-MPIC) shows that the model reproduces the general longitudinal gradient observed for both compounds and simulates elevated CO concentrations during the pollution events. However, it systematically overestimates the CO mixing ratios. It is suggested that the northern African biomass burning emissions used in the model are not distributed correctly (incorrect timing) and, in particular, that too high emissions from the region “northern Sudan-Sahel” are used for this period. The model does not capture the influence from industrial emissions from northern Africa, which may be caused by too strong diffusion of the plume.
Heald, C. L., D. J. Jacob, D. B. A. Jones, P. I. Palmer, J. A. Logan, D. G. Streets, G. W. Sachse, J. C. Gille, R. N. Hoffman, and T. Nehrkorn (2004), Comparative inverse analysis of satellite (MOPITT) and aircraft (TRACE-P) observations to estimate Asian sources of carbon monoxide, Journal of Geophysical Research: Atmospheres, 109(D23), n/a–n/a, doi:10.1029/2004JD005185.
We use an inverse model analysis to compare the top-down constraints on Asian sources of carbon monoxide (CO) in spring 2001 from (1) daily MOPITT satellite observations of CO columns over Asia and the neighboring oceans and (2) aircraft observations of CO concentrations in Asian outflow from the TRACE-P aircraft mission over the northwest Pacific. The inversion uses the maximum a posteriori method (MAP) and the GEOS-CHEM chemical transport model (CTM) as the forward model. Detailed error characterization is presented, including spatial correlation of the model transport error. Nighttime MOPITT observations appear to be biased and are excluded from the inverse analysis. We find that MOPITT and TRACE-P observations are independently consistent in the constraints that they provide on Asian CO sources, with the exception of southeast Asia for which the MOPITT observations support a more modest decrease in emissions than suggested by the aircraft observations. Our analysis indicates that the observations do not allow us to differentiate source types (i.e., anthropogenic versus biomass burning) within a region. MOPITT provides ten pieces of information to constrain the geographical distribution of CO sources, while TRACE-P provides only four. The greater information from MOPITT reflects its ability to observe all outflow and source regions. We conducted a number of sensitivity studies for the inverse model analysis using the MOPITT data. Temporal averaging of the MOPITT data (weekly and beyond) degrades the ability to constrain regional sources. Merging source regions beyond what is appropriate after careful selection of the state vector leads to significant aggregation errors. Calculations for an ensemble of realistic assumptions lead to a range of inverse model solutions that has greater uncertainty than the a posteriori errors for the MAP solution. Our best estimate of total Asian CO sources is 361 Tg yr−1, over half of which is attributed to east Asia.
Kar, J., H. Bremer, J. R. Drummond, Y. J. Rochon, D. B. A. Jones, F. Nichitiu, J. Zou, J. Liu, J. C. Gille, D. P. Edwards, M. N. Deeter, G. Francis, D. Ziskin, and J. Warner (2004), Evidence of vertical transport of carbon monoxide from Measurements of Pollution in the Troposphere (MOPITT), Geophysical Research Letters, 31, 23105, doi:10.1029/2004GL021128.
Vertical profiles of carbon monoxide (CO) mixing ratio retrieved from MOPITT measurements have been analyzed. We find that variations in the vertical structure of CO can be detected in the MOPITT data. The Asian summer monsoon plume in CO is observed for the first time as a strong enhancement of CO in the upper troposphere (UT) over India and southern China indicating the effect of deep convective transport. Similarly, zonal mean height latitude cross-sections for the months of September-December, 2002 indicate deep convective transport of CO from biomass burning in the southern tropics. These findings show that MOPITT CO can provide valuable information on vertical transport phenomena in the troposphere.
Kim, J. H., S. Na, M. J. Newchurch, and K. J. Ha (2004), Comparison of Scan-Angle Method and Convective Cloud Differential Method in Retrieving Tropospheric Ozone from TOMS, Environ Monit Assess, 92(1–3), 25–33, doi:10.1023/B:EMAS.0000014506.58857.db.
Tropospheric ozone, derived from the Scan-Angle Method (SAM) and the Convective Cloud Differential (CCD) method, exhibits a noticeable abundance over the South Atlantic, where it is associated with biomass-burning in the austral spring. This feature is also seen in the distribution of carbon monoxide observed from Measurements Of Pollution In The Troposphere (MOPITT). In the boreal burning season, however, the distribution of the results from SAM and MOPITT-CO present an enhancement related to the biomass-burning over North Africa that does not appear in the CCD results. The relationship of the results from SAM and MOPITT-CO is better than those of the results from the CCD and MOPITT-CO for the December-February period. Conversely, the latter relationship is better than the former for the October-November period. The two methods, SAM and CCD, show higher correlation in the southern burning season, but lower correlation in the northern burning season. The influence of biomass burning on ozone amounts is clearly seen in the SAM results of the elevated ozone over northern equatorial Africa during the northern burning season, but is not present in the CCD results.
Lamarque, J.-F., B. Khattatov, V. Yudin, D. P. Edwards, J. C. Gille, L. K. Emmons, M. N. Deeter, J. Warner, D. C. Ziskin, G. L. Francis, S. Ho, D. Mao, J. Chen, and J. R. Drummond (2004), Application of a bias estimator for the improved assimilation of Measurements of Pollution in the Troposphere (MOPITT) carbon monoxide retrievals, Journal of Geophysical Research: Atmospheres, 109(D16), n/a–n/a, doi:10.1029/2003JD004466.
This study discusses an improved technique for the assimilation of carbon monoxide retrievals from the Measurements of Pollution in the Troposphere (MOPITT) instrument in a chemistry-transport model using a suboptimal Kalman filter. An online bias estimator algorithm is employed to identify systematic biases in the model and account for them during the assimilation. Results suggest a large decline (both locally and globally) in the observation minus forecast diagnostics and provide insights about possible model deficiencies by enabling explicit examination of model biases.
Lee, S., G.-H. Choi, H.-S. Lim, and J.-H. Lee (2004), Global and Regional Distribution of Carbon Monoxide from MOPITT: Seasonal Distribution at 700 hPa, Environ Monit Assess, 92(1–3), 35–42, doi:10.1023/B:EMAS.0000014507.31728.48.
The Measurement of Pollution in the Troposphere (MOPITT) instrument is an eight-channel gas correlation radiometer, which was launchedon the Earth Observing System (EOS) Terra satellite in 1999. Carbon monoxide (CO) is one of the important trace gases because its concentration in the troposphere directly influences the concentrations of tropospheric hydroxyl (OH), which controls the lifetimes of tropospheric trace gases. CO traces the transport of global and regional pollutants from industrial activities and large scale biomass burning. The global and regional distributions of CO were analyzed using the MOPITT data for East Asia, which were compared with the ozone distributions. In general, seasonal CO variations are characterized by a peak in the spring, which decrease in the summer. This work also revealed that the seasonal cycles for CO are at a maximum in the spring and a minimum in the summer, with average concentrations ranging from 118 to 170 ppbv. The monthly average for CO shows a similar profile to that for O3. This fact clearly indicates that the high concentration of CO in the spring is possibly due to one of two causes: the photochemical production of CO in the troposphere, or the transport of the CO into East Asia. The seasonal cycles for CO and O3 in East Asia are extensively influenced by the seasonal exchanges of different air mass types due to the Asian monsoon. The continental air masses contain high concentrations of O3 and CO, due to the higher continental background concentrations, and sometimes to the contribution from regional pollution. In summer this transport pattern is reversed, where the Pacific marine air masses that prevail over Korea bring low concentrations of CO and O3, which tend to give the apparent summer minimums.
Nichitiu, F., J. R. Drummond, J. Zou, and R. Deschambault (2004), Solar particle events seen by the MOPITT instrument, Journal of Atmospheric and Solar-Terrestrial Physics, 66(18), 1797–1803, doi:10.1016/j.jastp.2004.06.002.
This paper reports on Device Single Events (DSEs) occurring in the Measurements Of Pollution In The Troposphere (MOPITT) space instrument piezoelectric accelerometers. It is found that DSEs correlate with the radiation environment, solar activity and high intensity Solar Proton Events.
Niu, J., M. N. Deeter, J. C. Gille, D. P. Edwards, D. C. Ziskin, G. L. Francis, A. J. Hills, and M. W. Smith (2004), Carbon Monoxide Total Column Retrievals by Use of the Measurements of Pollution in the Troposphere Airborne Test Radiometer, Appl. Opt., 43(24), 4685–4696, doi:10.1364/AO.43.004685.
The Measurements of Pollution in the Troposphere (MOPITT) Airborne Test Radiometer (MATR) uses gas correlation filter radiometry from high-altitude aircraft to measure tropospheric carbon monoxide. This radiometer is used in support of the ongoing validation campaign for the MOPITT instrument aboard the Earth Observation System Terra satellite. A recent study of MATR CO retrievals that used data from the autumn of 2001 in the western United States is presented. Retrievals of the CO total column were performed and compared to in situ sampling with less than 10% retrieval error. Effects that influence retrieval, such as instrument sensitivity, retrieval sensitivity, and the bias between observations and the radiative transfer model, are discussed. Comparisons of MATR and MOPITT retrievals show promising consistency. A preliminary interpretation of MATR results is also presented.
Pétron, G., C. Granier, B. Khattatov, V. Yudin, J.-F. Lamarque, L. Emmons, J. Gille, and D. P. Edwards (2004), Monthly CO surface sources inventory based on the 2000–2001 MOPITT satellite data, Geophysical Research Letters, 31(21), n/a–n/a, doi:10.1029/2004GL020560.
This paper presents results of the inverse modeling of carbon monoxide surface sources on a monthly and regional basis using the MOPITT (Measurement Of the Pollution In The Troposphere) CO retrievals. The targeted time period is from April 2000 to March 2001. A sequential and time-dependent inversion scheme is implemented to correct an a priori set of monthly mean CO sources. The a posteriori estimates for the total anthropogenic (fossil fuel + biofuel + biomass burning) surface sources of CO in TgCO/yr are 509 in Asia, 267 in Africa, 140 in North America, 90 in Europe and 84 in Central and South America. Inverting on a monthly scale allows one to assess a corrected seasonality specific to each source type and each region. Forward CTM simulations with the a posteriori emissions show a substantial improvement of the agreement between modeled CO and independent in situ observations.
Pfister, G., G. Pétron, L. K. Emmons, J. C. Gille, D. P. Edwards, J.-F. Lamarque, J.-L. Attie, C. Granier, and P. C. Novelli (2004), Evaluation of CO simulations and the analysis of the CO budget for Europe, Journal of Geophysical Research: Atmospheres, 109(D19), n/a–n/a, doi:10.1029/2004JD004691.
CO is a well-suited indicator for the transport of pollutants in the troposphere on a regional and global scale. For the study presented here, simulations of CO concentrations from a global chemistry transport model (MOZART-2), with the CO being tagged according to the emission type and the source region, have been used to diagnose the contributions of different processes and regions to the CO burden over Europe. Model simulations have been performed with both a priori emissions and an optimized set of CO surface emissions derived from the inversion of CO retrievals of the Measurements of Pollution in the Troposphere (MOPITT) remote sensing instrument. The annual mean difference between the modeled and the observed CO at 850 hPa over Europe is −38 ± 13 ppb with the a priori set of emissions and −7 ± 7 ppb when the optimized emissions are employed in the model. The general difficulties arising from an intercomparison of remote sensing data with model simulations are discussed. Besides data from MOPITT, ground-based CO measurements have been employed in the evaluation of the model and its emissions. The comparisons show that the model represents the background conditions as well as large-scale transport relatively well. The budget analysis reveals the predominant impact of the European emissions on CO concentrations near the surface, and a strong impact of sources from Asia and North America on the CO burden in the free troposphere over Europe. On average, the largest contribution (67%) to the anthropogenic (fossil and biofuel sources, biomass burning) CO at the surface originates from regional anthropogenic sources, but further significant impact is evident from North America (14%) and Asia (15%). With increasing altitude, anthropogenic CO from Asia and North America gains in importance, reaching maximum contributions of 32% for North American CO at 500 hPa and 50% for Asian CO at 200 hPa. The impact of European emissions weakens with increasing altitude (8% at 500 hPa).
Yudin, V. A., G. Pétron, J.-F. Lamarque, B. V. Khattatov, P. G. Hess, L. V. Lyjak, J. C. Gille, D. P. Edwards, M. N. Deeter, and L. K. Emmons (2004), Assimilation of the 2000–2001 CO MOPITT retrievals with optimized surface emissions, Geophysical Research Letters, 31(20), n/a–n/a, doi:10.1029/2004GL021037.
The multi-year retrievals of carbon monoxide (CO) by the MOPITT (Measurements Of Pollution In The Troposphere) instrument onboard the NASA Terra satellite provide an opportunity for the first time to study quantitatively the transport and sources of pollution in the mid-troposphere. This paper presents the assimilation of the Phase I (March 3, 2000–May 6, 2001) MOPITT retrievals with optimized CO emissions constrained by monthly MOPITT CO data. The observed-minus-forecast (OmF) CO distributions illustrate improvement of this data analysis compared with the assimilation that employs climatological surface fluxes.
Zheng, Y. G., P. J. Zhu, C. Y. Chan, L. Y. Chan, H. Cui, X. D. Zheng, Q. Zhao, and Y. Qin (2004), Influence of biomass burning in Southeast Asia on the lower tropospheric ozone distribution over South China, Chinese J. Geophys.-Chinese Ed., 47(5), 767–775.
Ozone enhancement was observed in the lower troposphere over Hong Kong and Kunming on March 7 and 8, 2001 using the electrochemical concentration cell ozonesondes. Based on the data of NCEP, Total Column Ozone, the numerical simulation of MM5, AI from TOMS, aerosol optical depths from MODIS, and CO concentrations from MOPITT, we analyze the influence of the biomass burning in Southeast Asia on the ozone distribution in the lower troposphere over Hong Kong and Kunming. The transport of the emissions of biomass burning shows that the enhancement of ozone in the lower troposphere over Hong Kong and Kunming is from the region where large-scale fires occurred in Southeast Asia. TOMS AI images and the atmospheric background circulations reveal that the biomass burning plumes in Southeast Asia are transported to downwind South China and lead to enhancement of the ozone concentrations in the lower troposphere.

2003

Barret, B., M. De Mazière, and E. Mahieu (2003), Ground-based FTIR measurements of CO from the Jungfraujoch: characterisation and comparison with in situ surface and MOPITT data, Atmos. Chem. Phys., 3(6), 2217–2223, doi:10.5194/acp-3-2217-2003.
CO vertical profiles have been retrieved from solar absorption FTIR spectra recorded at the NDSC station of the Jungfraujoch (46.5° N, 8° E and 3580 m a.s.l.) for the period from January 1997 to May 2001. The characterisation of these profiles has been established by an information content analysis and an estimation of the error budgets. A partial validation of the profiles has been performed through comparisons with correlative measurements. The average volume mixing ratios (vmr) in the 3 km layer above the station have been compared with coincident surface measurements. The agreement between monthly means from both measurement techniques is very good, with a correlation coefficient of 0.87, and no significant bias observed. The FTIR total columns have also been compared to CO partial columns above 3580 m a.s.l. derived from the MOPITT (Measurement Of Pollution In The Troposphere) instrument for the period March 2000 to May 2001. Relative to the FTIR columns, the MOPITT partial columns exhibit a positive bias of 8±8% for daytime and of 4±7% for nighttime measurements.
Deeter, M. N., L. K. Emmons, G. L. Francis, D. P. Edwards, J. C. Gille, J. X. Warner, B. Khattatov, D. Ziskin, J.-F. Lamarque, S.-P. Ho, V. Yudin, J.-L. Attié, D. Packman, J. Chen, D. Mao, and J. R. Drummond (2003), Operational carbon monoxide retrieval algorithm and selected results for the MOPITT instrument, Journal of Geophysical Research: Atmospheres, 108(D14), n/a–n/a, doi:10.1029/2002JD003186.
Measurements of Pollution in the Troposphere (MOPITT) is a new remote sensing instrument aboard the Earth Observing System (EOS) “Terra” satellite which exploits gas correlation radiometry principles to quantify tropospheric concentrations of carbon monoxide (CO) and methane (CH4). The MOPITT CO retrieval algorithm employs a nonlinear optimal estimation method to iteratively solve for the CO profile which is statistically most consistent with both the satellite-measured radiances and a priori information. The algorithm’s theoretical basis is described in terms of the observed radiances and their weighting functions, the a priori information, and the retrieval averaging kernels. Examples of actual CO retrievals over scenes with contrasting pollution conditions are demonstrated, and interpreted in the context of the retrieval averaging kernels and a priori.
Edwards, D. P., J.-F. Lamarque, J.-L. Attié, L. K. Emmons, A. Richter, J.-P. Cammas, J. C. Gille, G. L. Francis, M. N. Deeter, J. Warner, D. C. Ziskin, L. V. Lyjak, J. R. Drummond, and J. P. Burrows (2003), Tropospheric ozone over the tropical Atlantic: A satellite perspective, Journal of Geophysical Research: Atmospheres, 108(D8), n/a–n/a, doi:10.1029/2002JD002927.
We use satellite sensor measurements to obtain a broad picture of the processes affecting tropical tropospheric O3 production over Africa and the Atlantic in the early part of the year. Terra/MOPITT CO retrievals correlate well with biomass burning fire counts observed by the TRMM/VIRS instrument in Northern Hemisphere savanna regions and allow investigation of the subsequent convection of the biomass burning plume at the intertropical convergence zone and interhemispheric transport. Measurements of NO2 from the ERS-2/GOME instrument enable identification of two important tropical sources of this O3 precursor, biomass burning and lightning. Good correlation is seen between NO2 retrievals and TRMM/LIS lightning flash observations in southern African regions free of biomass burning, thus indicating a probable lightning source of NOx. The combination of MOPITT CO, GOME NO2, and TRMM fire and lightning flash counts provides a powerful tool for investigating the tropospheric production of O3 precursors. These data are used in conjunction with the MOZART-2 chemical transport model to investigate the early year tropical Atlantic tropospheric O3 distribution using January 2001 as a case study. Inconsistencies between the various tropical tropospheric O3 column products obtained from EP/TOMS data, and between these products, in situ measurements, and modeling, have led to questions about how the Northern Hemisphere biomass burning is connected to the TOMS derived O3 maximum in the tropical southern Atlantic. We show that the early year tropical O3 distribution is actually characterized by two maxima. The first arises due to biomass burning emissions, is located near the Northern Hemisphere fires, and is most evident in the lower troposphere. The second is located in the southern tropical Atlantic midtroposphere, and results from NOx produced by lightning over southern Africa and South America.
Heald, C. L., D. J. Jacob, A. M. Fiore, L. K. Emmons, J. C. Gille, M. N. Deeter, J. Warner, D. P. Edwards, J. H. Crawford, A. J. Hamlin, G. W. Sachse, E. V. Browell, M. A. Avery, S. A. Vay, D. J. Westberg, D. R. Blake, H. B. Singh, S. T. Sandholm, R. W. Talbot, and H. E. Fuelberg (2003), Asian outflow and trans-Pacific transport of carbon monoxide and ozone pollution: An integrated satellite, aircraft, and model perspective, Journal of Geophysical Research: Atmospheres, 108(D24), n/a–n/a, doi:10.1029/2003JD003507.
Satellite observations of carbon monoxide (CO) from the Measurements of Pollution in the Troposphere (MOPITT) instrument are combined with measurements from the Transport and Chemical Evolution Over the Pacific (TRACE-P) aircraft mission over the northwest Pacific and with a global three-dimensional chemical transport model (GEOS-CHEM) to quantify Asian pollution outflow and its trans-Pacific transport during spring 2001. Global CO column distributions in MOPITT and GEOS-CHEM are highly correlated (R2 = 0.87), with no significant model bias. The largest regional bias is over Southeast Asia, where the model is 18% too high. A 60% decrease of regional biomass burning emissions in the model (to 39 Tg yr−1) would correct the discrepancy; this result is consistent with TRACE-P observations. MOPITT and TRACE-P also give consistent constraints on the Chinese source of CO from fuel combustion (181 Tg CO yr−1). Four major events of trans-Pacific transport of Asian pollution in spring 2001 were seen by MOPITT, in situ platforms, and GEOS-CHEM. One of them was sampled by TRACE-P (26–27 February) as a succession of pollution layers over the northeast Pacific. These layers all originated from one single event of Asian outflow that split into northern and southern plumes over the central Pacific. The northern plume (sampled at 6–8 km off California) had no ozone enhancement. The southern subsiding plume (sampled at 2–4 km west of Hawaii) contained a 8–17 ppbv ozone enhancement, driven by decomposition of peroxyacetylnitrate (PAN) to nitrogen oxides (NOx). This result suggests that PAN decomposition in trans-Pacific pollution plumes subsiding over the United States could lead to significant enhancements of surface ozone.
Jacob, D. J., J. H. Crawford, M. M. Kleb, V. S. Connors, R. J. Bendura, J. L. Raper, G. W. Sachse, J. C. Gille, L. Emmons, and C. L. Heald (2003), Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission: Design, execution, and first results, Journal of Geophysical Research (Atmospheres), 108, 9000, doi:10.1029/2002JD003276.
The NASA Transport and Chemical Evolution over the Pacific (TRACE-P) aircraft mission was conducted in February-April 2001 over the NW Pacific (1) to characterize the Asian chemical outflow and relate it quantitatively to its sources and (2) to determine its chemical evolution. It used two aircraft, a DC-8 and a P-3B, operating out of Hong Kong and Yokota Air Force Base (near Tokyo), with secondary sites in Hawaii, Wake Island, Guam, Okinawa, and Midway. The aircraft carried instrumentation for measurements of long-lived greenhouse gases, ozone and its precursors, aerosols and their precursors, related species, and chemical tracers. Five chemical transport models (CTMs) were used for chemical forecasting. Customized bottom-up emission inventories for East Asia were generated prior to the mission to support chemical forecasting and to serve as a priori for evaluation with the aircraft data. Validation flights were conducted for the Measurements Of Pollution In The Troposphere (MOPITT) satellite instrument and revealed little bias (6 +/- 2%) in the MOPITT measurements of CO columns. A major event of transpacific Asian pollution was characterized through combined analysis of TRACE-P and MOPITT data. The TRACE-P observations showed that cold fronts sweeping across East Asia and the associated warm conveyor belts (WCBs) are the dominant pathway for Asian outflow to the Pacific in spring. The WCBs lift both anthropogenic and biomass burning (SE Asia) effluents to the free troposphere, resulting in complex chemical signatures. The TRACE-P data are in general consistent with a priori emission inventories, lending confidence in our ability to quantify Asian emissions from socioeconomic data and emission factors. However, the residential combustion source in rural China was found to be much larger than the a priori, and there were also unexplained chemical enhancements (HCN, CH3Cl, OCS, alkylnitrates) in Chinese urban plumes. The Asian source of CCl4 was found to be much higher than government estimates. Measurements of HCN and CH3CN indicated a dominant biomass burning source and ocean sink for both gases. Large fractions of sulfate and nitrate were found to be present in dust aerosols. Photochemical activity in the Asian outflow was strongly reduced by aerosol attenuation of UV radiation, with major implications for the concentrations of HOx radicals. New particle formation, apparently from ternary nucleation involving NH3, was observed in Chinese urban plumes.
Lamarque, J.-F., and J. C. Gille (2003), Improving the modeling of error variance evolution in the assimilation of chemical species: Application to MOPITT data, Geophysical Research Letters, 30(9), n/a–n/a, doi:10.1029/2003GL016994.
This study focuses on improvement to the modeling of the evolution of the model error variance in the problem of assimilating satellite observations of chemical species. The model error variance evolution equation for the assimilation of CO is described here with localized sources in addition to transport and error growth. The assimilation of carbon monoxide (CO) observations from MOPITT is performed using a sub-optimal Kalman filter in the MOZART-2 chemistry-transport model. It is shown that this new approach can dramatically improve the ability of the assimilation to diverge from erroneous model-generated features.
Lamarque, J.-F., D. P. Edwards, L. K. Emmons, J. C. Gille, O. Wilhelmi, C. Gerbig, D. Prevedel, M. N. Deeter, J. Warner, D. C. Ziskin, B. Khattatov, G. L. Francis, V. Yudin, S. Ho, D. Mao, J. Chen, and J. R. Drummond (2003), Identification of CO plumes from MOPITT data: Application to the August 2000 Idaho-Montana forest fires, Geophysical Research Letters, 30(13), n/a–n/a, doi:10.1029/2003GL017503.
This study focuses on the identification of carbon monoxide (CO) released during the forest fires that took place primarily in Montana and Idaho during the summer of 2000. We focus our analysis on the most intense period of the fires during the second half of August. During that period, the MOPITT instrument onboard the EOS-Terra platform collected extensive measurements of CO. A simulation of the dispersal of the CO from the fires, constrained by the AVHRR observations of fire location and extent, clearly identifies the affected regions. The model results are compared with the CO observations from the COBRA experiment flight on August 19. Using these various data, we are able to identify the transport of the CO plume originating from the fires. In particular, it is shown that the CO travels eastward from the fires, reaching as far as the East coast and the Gulf of Mexico in a few days. Although the distribution of CO over the U.S. is clearly a combination of a variety of sources it is found that wildfires are a strong component of the summer tropospheric CO.
Rodgers, C. D., and B. J. Connor (2003), Intercomparison of remote sounding instruments, Journal of Geophysical Research: Atmospheres, 108(D3), n/a–n/a, doi:10.1029/2002JD002299.
When intercomparing measurements made by remote sounders, it is necessary to make due allowance for the differing characteristics of the observing systems, particularly their averaging kernels and error covariances. We develop the methods required to do this, applicable to any kind of retrieval method, not only to optimal estimators. We show how profiles and derived quantities such as the total column of a constituent may be properly compared, yielding different averaging kernels. We find that the effect of different averaging kernels can be reduced if the retrieval or the derived quantity of one instrument is simulated using the retrieval of the other. We also show how combinations of measured signals can be found, which can be compared directly. To illustrate these methods, we apply them to two real instruments, calculating the expected amplitudes and variabilities of the diagnostics for a comparison of CO measurements made by a ground-based Fourier Transform spectrometer (FTIR) and the “measurement of pollution in the troposphere” instrument (MOPITT), which is mounted on the EOS Terra platform. The main conclusions for this case are the following: (1) Direct comparison of retrieved profiles is not satisfactory, because the expected standard deviation of the difference is around half of the expected natural variability of the true atmospheric profiles. (2) Comparison of the MOPITT profile retrieval with a simulation using FTIR is much more useful, though still not ideal, with expected standard deviation of differences of around 20% of the expected natural variability. (3) Direct comparison of total columns gives an expected standard deviation of about 9%, while comparison of MOPITT with a simulation derived from FTIR improved this to 8%. (4) There is only one combination of measured signals that can be usefully compared. The difference is expected to have a standard deviation of about 5.5% of the expected natural variability, which is mostly due to noise.
Wehr, R., E. McKernan, A. Vitcu, R. Ciurylo, and J. R. Drummond (2003), Dynamic Spectroscopic Measurements of the Temperature and Pressure Cycles in a MOPITT Pressure Modulator Cell, Appl. Opt., 42(33), 6595–6604, doi:10.1364/AO.42.006595.
The temperature and pressure cycles inside a pressure modulator cell (PMC) of the type used for gas-correlation radiometry aboard the Measurements of Pollution in the Troposphere (MOPITT) satellite instrument have been determined from dynamic measurements of the spectral line shapes of the R(0) and R(18) transitions in the fundamental vibrational-rotational band of carbon monoxide. The line strengths and linewidths were used to calculate the temperature and pressure, respectively, with a temporal resolution of approximately 200 μs, or 1/100 of a PMC cycle. The results are compared with a thermodynamic box model.
Yu, L., L. Weiliang, Z. Xiuji, I. S. A. Isaksen, J. K. Sundet, and H. Jinhai (2003), The possible influences of the increasing anthropogenic emissions in India on tropospheric ozone and OH, Adv. Atmos. Sci., 20(6), 968–977, doi:10.1007/BF02915520.
A 3-D chemical transport model (OSLO CTM2) is used to investigate the influences of the increasing anthropogenic emission in India. The model is capable of reproducing the observational results of the INDOEX experiment and the measurements in summer over India well. The model results show that when NO x and CO emissions in India are doubled, ozone concentration increases, and global average OH decreases a little. Under the effects of the Indian summer monsoon, NO x and CO in India are efficiently transported into the middle and upper troposphere by the upward current and the convective activities so that the NO x , CO, and ozone in the middle and upper troposphere significantly increase with the increasing NO x and CO emissions. These increases extensively influence a part of Asia, Africa, and Europe, and persist from June to September.

2002

Clerbaux, C., J. Hadji-Lazaro, S. Payan, C. Camy-Peyret, J. Wang, D. P. Edwards, and M. Luo (2002), Retrieval of CO from nadir remote-sensing measurements in the infrared by use of four different inversion algorithms, Appl. Opt., 41(33), 7068–7078, doi:10.1364/AO.41.007068.
Four inversion schemes based on various retrieval approaches (digital gas correlation, nonlinear least squares, global fit adjustment, and neural networks) developed to retrieve CO from nadir radiances measured by such downward-looking satelliteborne instruments as the Measurement of Pollution in the Troposphere (MOPITT), the Tropospheric Emission Spectrometer (TES), and the Infrared Atmospheric Sounding Interferometer (IASI) instruments were compared both for simulated cases and for atmospheric spectra recorded by the Interferometric Monitor for Greenhouse Gases (IMG). The sensitivity of the retrieved CO total column amount to properties that may affect the inversion accuracy (noise, ancillary temperature profile, and water-vapor content) was investigated. The CO column amounts for the simulated radiance spectra agreed within 4%, whereas larger discrepancies were obtained when atmospheric spectra recorded by the IMG instrument were analyzed. The assumed vertical temperature profile is shown to be a critical parameter for accurate CO retrieval. The instrument’s line shape was also identified as a possible cause of disagreement among the results provided by the groups of scientists who are participating in this study.
Deeter, M. N., G. L. Francis, D. P. Edwards, J. C. Gille, E. McKernan, and J. R. Drummond (2002), Operational Validation of the MOPITT Instrument Optical Filters*, Journal of Atmospheric and Oceanic Technology, 19, 1772, doi:10.1175/1520-0426(2002)019<1772:OVOTMI>2.0.CO;2.
Optical bandpass filters in the Measurements of Pollution in the Troposphere (MOPITT) satellite remote sensing instrument selectivity limit the throughput radiance to absorptive spectral bands associated with the satellite-observed trace gases CO and CH4. Precise specification of the spectral characteristics of these filters is required to optimize retrieval accuracy. The effects and potential causes of spectral shifts in the optical bandpass filter profiles are described. Specifically, a shift in the assumed bandpass profile produces a relative bias between the calibrated satellite radiances and the corresponding values calculated by an instrument-specific forward radiative transfer model. Conversely, it is shown that the observed bias (as identified and quantified using operational MOPITT satellite radiance data) can be used to determine the relative spectral shift between the nominal (prelaunch) filter profiles and the true operational (in orbit) profiles. Revising both the radiance calibration algorithm and the forward radiative transfer model to account for the revised filter profiles effectively eliminates the radiance biases.

2001

He, H., W. Wallace McMillan, R. O. Knuteson, and W. F. Feltz (2001), Tropospheric carbon monoxide column density retrieval during Pre-launch MOPITT Validation exercise, Atmospheric Environment, 35(3), 509–514, doi:10.1016/S1352-2310(00)00334-4.
The tropospheric carbon monoxide (CO) column density over the United States Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Program Southern Great Plains (SGP) Central Facility near Lamont, Oklahoma (latitude 36°37′N, longitude 97°30′W) during the Pre-launch MOPITT Validation Exercise (Pre-MOVE) is retrieved from infrared spectra obtained by the ground-based Atmospheric Emitted Radiance Interferometer (AERI). This paper reports the first tropospheric CO time series retrieved from an AERI. With spectra measured every 8 min, CO retrieved from AERI spectra has a much higher temporal resolution than from any other ground-based instrument measuring atmospheric emission. The retrieved CO column density time series is examined using local meteorological data. Synoptic atmospheric conditions are found to have a controlling effect on tropospheric CO. During 2–4 March, 1998, a southerly to easterly surface wind brought an airmass with higher CO column density over the SGP Central Facility (SGPCF), whereas northerly and/or westerly surface winds tended to reduce the CO column density.
Warner, J. X., J. C. Gille, D. P. Edwards, D. C. Ziskin, M. W. Smith, P. L. Bailey, and L. Rokke (2001), Cloud Detection and Clearing for the Earth Observing System Terra Satellite Measurements of Pollution in the Troposphere (MOPITT) Experiment, Appl. Opt., 40(8), 1269–1284, doi:10.1364/AO.40.001269.
The Measurements of Pollution in the Troposphere (MOPITT) instrument, which was launched aboard the Earth Observing System (EOS) Terra spacecraft on 18 December 1999, is designed to measure tropospheric CO and CH4 by use of a nadir-viewing geometry. The measurements are taken at 4.7 μm in the thermal emission and absorption for the CO mixing ratio profile retrieval and at 2.3 and 2.2 μm in the reflected solar region for the total CO column amount and CH4 column amount retrieval, respectively. To achieve the required measurement accuracy, it is critical to identify and remove cloud contamination in the radiometric signals. We describe an algorithm to detect cloudy pixels, to reconstruct clear column radiance for pixels with partial cloud covers, and to estimate equivalent cloud top height for overcast conditions to allow CO profile retrievals above clouds. The MOPITT channel radiances, as well as the first-guess calculations, are simulated with a fast forward model with input atmospheric profiles from ancillary data sets. The precision of the retrieved CO profiles and total column amounts in cloudy atmospheres is within the expected ∓10% range. Validations of the cloud-detecting thresholds with the moderate-resolution imaging spectroradiometer airborne simulator data and MOPITT airborne test radiometer measurements were performed. The validation results showed that the MOPITT cloud detection thresholds work well for scenes covered with more than 5–10% cloud cover if the uncertainties in the model input profiles are less than 2 K for temperature, 10% for water vapor, and 5% for CO and CH4.

2000

Edwards, D. P., and G. L. Francis (2000), Improvements to the correlated-k radiative transfer method: Application to satellite infrared sounding, Journal of Geophysical Research: Atmospheres, 105(D14), 18135–18156, doi:10.1029/2000JD900131.
This paper presents a new radiative transfer model based on the correlated-k technique that is particularly suitable for applications associated with broadband infrared satellite remote sounding of the atmosphere. We describe new developments to the approach which improve the accuracy of correlated-k distribution radiative transfer calculations. These include methods to model an instrument response function, spectral line overlap for multiple gases, and the spectral variation of solar and thermal source functions. We also describe an approach to improving vertical spectral correlation along ray paths through a nonhomogeneous atmosphere. For a radiative transfer model to be efficient as the forward model of a retrieval scheme, the calculation of analytical Jacobians is particularly important. This is implemented in the model using a variation on the correlated-k approach. The application of the new model, RADCKD, is demonstrated with example calculations for the EOS Terra satellite Measurements of Pollution in the Troposphere (MOPITT) instrument.
Wang, J., J. C. Gille, H. E. Revercomb, and V. P. Walden (2000), Validation Study of the MOPITT Retrieval Algorithm: Carbon Monoxide Retrieval from IMG Observations during WINCE, Journal of Atmospheric and Oceanic Technology, 17(10), 1285–1295, doi:10.1175/1520-0426(2000)017<1285:VSOTMR>2.0.CO;2.
The Measurement of Pollution in the Troposphere (MOPITT) instrument is an eight-channel gas correlation radiometer selected for the Earth Observing System (EOS) Terra spacecraft launched in December 1999. Algorithms for the retrieval of tropospheric carbon monoxide (CO) profiles from MOPITT measurements have been developed. In this paper, validation studies of the MOPITT CO retrieval algorithm using observations by the Interferometric Monitor for greenhouse Gases (IMG) during the Winter Clouds Experiment (WINCE) conducted from 23 January to 13 February 1997 are described. Synthetic radiance spectra calculated by a line-by-line radiative transfer model, FASCOD3, using the retrieved CO profile agrees well with IMG-measured radiance spectra. Observations by the Moderate Resolution Imaging Spectrometer (MODIS) Airborne Simulator (MAS) from the NASA ER-2 platform during WINCE were successfully used to assist in the identification of clear and cloudy IMG observations.

1999

Beiying, W., and J. Gille (1999a), Retrieval of tropospheric co profiles using correlation radiometer: I. retrieval experiments for a clear atmosphere, Adv. Atmos. Sci., 16(3), 343–354, doi:10.1007/s00376-999-0013-4.
This paper discusses the retrieval scheme associated with the gas correlated radiometer MOPITT which will be on board of EOS-AM1 to measure the global vertical profiles of carbon monoxide. The vertical resolution and retrieval errors caused by errors in the temperature profiles and in the surface temperature have been assessed. The main results are: Assuming the noise equivalent radiance (NER) of 1.8 × 105 W m-2 sr-1, the surface temperature can be deduced from the wide band signals with uncertainty less than 1 K, and the atmospheric term of the modulated signal can be deduced with errors almost equal to the NER which does not significantly increase errors in the retrieved CO profiles. With typical uncertainty in temperature profiles, errors in the retrieved profiles at latitudes lower than 70‡ are generally less than 20% with the first guess of 100 ppbv. (If a better first guess was used, the errors may decrease). By incorporating the total column CO amount derived from the reflected solar radiation in 2.3 Μm spectral region into the retrieval, the accuracy of the retrieved CO profile below 6 km may be greatly improved. In the retrieval experiment with 10 CO profiles representing the typical CO profiles, the r.m.s. relative/ absolute errors of the retrieved CO profiles are about 10% / 15-20 ppbv.
Beiying, W., and J. Gille (1999b), Retrieval of tropospheric co profiles using correlation radiometer. ii: effects of other gases and the retrieval in cloudy atmosphere, Adv. Atmos. Sci., 16(4), 507–522, doi:10.1007/s00376-999-0027-y.
The effects of methane, ozone, water vapor and nitrous oxide on the retrieval of tropospheric CO profiles using correlation radiometer have been assessed. The scheme of the retrieval in the presence of solid clouds have been proposed. The effect of methane and nitrous oxide can be well accounted by their mean profile, and that of ozone can be represented by a typical middle latitude ozone profile, while for water vapor, less than 50% uncertainty is required. With the assumption of blackbody for cloud surface, the CO profile may be retrieved for low and middle solid clouds. However, the retrieval of CO profile will lose quality for high clouds.
Edwards, D. P., C. M. Halvorson, and J. C. Gille (1999), Radiative transfer modeling for the EOS Terra satellite Measurement of Pollution in the Troposphere (MOPITT) instrument, Journal of Geophysical Research: Atmospheres, 104(D14), 16755–16775, doi:10.1029/1999JD900167.
This paper describes the radiative transfer modeling effort in support of the EOS Measurements of Pollution in the Troposphere (MOPITT) instrument. MOPITT is due to be launched on the AM-1 Terra platform in the summer of 1999 and is a nadir-viewing gas correlation radiometer designed to measure CO and CH4 in the troposphere using a CO thermal channel at 4.7 μm and reflected solar channels for CO at 2.3 μm and CH4 at 2.2 μm. We describe the spectroscopic considerations and radiative transfer studies that have been performed for this instrument and the implications for operational algorithm design. We outline the construction of MOPITT project forward models, both the research codes and the fast transmittance module that forms part of the operational retrieval algorithm. Several different approaches have been considered for these models: full line-by-line calculations using the general purpose line-by-line transmittance and radiance model GENLN2, absorption coefficient look-up tables, and regression techniques using a recurrence parameterization of transmittance. These models are capable of reproducing MOPITT channel signals and their dependence on temperature, viewing geometry, and the mixing ratios of target and contaminating gases.
Tolton, B. T., and J. R. Drummond (1999), Measurements of the Atmospheric Carbon Monoxide Column with a Ground-Based Length-Modulated Radiometer, Appl. Opt., 38(10), 1897–1909, doi:10.1364/AO.38.001897.
A ground-based remote sounding instrument that uses a length-modulated radiometer to measure the total atmospheric carbon monoxide (CO) column has been built. Measurements made in Toronto during August and September of 1994 showed average CO concentrations of 125 to 150 parts per billion in volume (ppbv, parts in 109). Similar measurements made in October at a rural site 80 km north of Toronto showed concentrations of approximately 100 ppbv. The latter measurements are shown to agree with other simultaneous ground- and satellite-based measurements. This instrument is an advanced prototype of the MOPITT (Measurements of Pollution in the Troposphere) satellite instrument.
Wang, J., J. C. Gille, P. L. Bailey, J. R. Drummond, and L. Pan (1999a), Instrument Sensitivity and Error Analysis for the Remote Sensing of Tropospheric Carbon Monoxide by MOPITT, Journal of Atmospheric and Oceanic Technology, 16(4), 465–474, doi:10.1175/1520-0426(1999)016<0465:ISAEAF>2.0.CO;2.
Measurement of Pollution in the Troposphere (MOPITT) is an eight-channel gas correlation radiometer selected for the Earth Observing System AM-1 platform to be launched in 1999. Its primary objectives are the measurement of tropospheric carbon monoxide (CO) and methane (CH sub(4)). In this paper, the sensitivities of instrument signals and CO retrieval errors to various instrument parameters, especially the gas cell pressure and temperature variations, instrument radiometric noise, and ancillary data errors (such as atmospheric temperature and water vapor profile errors), are presented and discussed. In the MOPITT pressure modulator cell pressure sensitivity study, the instrument calibration process is considered, which leads to the relaxation of previous stringent requirements on the accuracy of in-orbit cell pressure monitoring. The approach of MOPITT CO retrieval error analysis is described, and the error analysis results are compared with retrieval simulation statistics. The error analysis results indicate that tropospheric CO distributions can be retrieved with a precision of 10% for most of the troposphere.
Wang, J., J. C. Gille, P. L. Bailey, L. Pan, D. Edwards, and J. R. Drummond (1999b), Retrieval of Tropospheric Carbon Monoxide Profiles from High-Resolution Interferometer Observations: A New Digital Gas Correlation (DGC)Method and Applications, Journal of the Atmospheric Sciences, 56(2), 219–232, doi:10.1175/1520-0469(1999)056<0219:ROTCMP>2.0.CO;2.
Global tropospheric carbon monoxide (CO) distributions can be retrieved from observations by spaceborne gas correlation radiometers and high-resolution interferometers. The Measurement of Pollution in the Troposphere (MOPITT) is a gas correlation radiometer designed for tropospheric CO and CH4 remote sensing. It is being developed at the University of Toronto and the National Center for Atmospheric Research for launch on the EOS/AM-1 platform in 1999. Spaceborne high-resolution interferometers with troposphere CO remote sensing capability include the Interferometric Monitor for Greenhouse gases (IMG) instrument and the Troposphere Emission Spectrometer (TES). IMG was developed by the Ministry of International Trade and Industry (MITI) of Japan. It was on the ADEOS-1 spacecraft launched in October 1996. TES is being developed by the Jet Propulsion Laboratory for launch on the EOS/CHEM-1 platform in 2002.For the purpose of testing the MOPITT data processing algorithms before launch, a new digital gas correlation (DGC) method was developed. This method makes it possible to use existing IMG observations to validate the MOPITT retrieval algorithms. The DGC method also allows the retrieval of global troposphere CO from MOPITT, IMG, and TES observations with a consistent algorithm. The retrieved CO profiles can be intercompared, and a consistent long time series of tropospheric CO measurements can be created. In this paper, the DGC method is described. The procedures for using the DGC method to retrieve atmospheric trace species profiles are discussed. As an example, CO profiles from IMG observations have been retrieved with the DGC method as a demonstration of its feasibility and application in MOPITT retrieval algorithm validation.

1998

Clerbaux, C., P. Chazette, J. Hadji-Lazaro, G. Mégie, J.-F. Müller, and S. A. Clough (1998), Remote sensing of CO, CH4, and O3 using a spaceborne nadir-viewing interferometer, Journal of Geophysical Research: Atmospheres, 103(D15), 18999–19013, doi:10.1029/98JD01422.
Within the next 5 years, several instruments launched on polar orbiting satellites will provide high-resolution infrared remote-sensing measurements of CO, CH4, and O3 on a global scale. The upwelling spectral radiances to be recorded by a nadir-looking remote sensor have been simulated using a high-resolution radiative code (line-by-line radiative transfer model (LBLRTM)) coupled to a three-dimensional chemical transport model (intermediate model of the annual and global evolution of species (IMAGES)). The instrumental specifications of the Fourier transform interferometric monitor for greenhouse gases/Advanced Earth Observing System (IMG/ADEOS) and infrared atmospheric sounding interferometer (IASI/METOP) were used to generate realistic data. Calculations have been performed to assess the sensitivity of the nadir spectral radiances to changes in the gas concentration, temperature profile and to instrumental characteristics. We provide spectral intervals for an efficient retrieval of these species, together with a set of climatological tropospheric standard mixing ratio profiles.
Kaufman, Y. J., D. D. Herring, K. J. Ranson, and G. J. Collatz (1998), Earth Observing System AM1 mission to Earth, IEEE Transactions on Geoscience and Remote Sensing, 36, 1045–1055, doi:10.1109/36.700989.
In 1998, NASA launches EOS-AMI, the first of a series of the Earth Observing System (EOS) satellites. EOS will monitor the evolution of the state of the earth for 18 years, starting with the morning observations of EOS-AM1 (10:30 a.m. equatorial crossing time). An integrated view of the earth, as planned by EOS, is needed to study the interchange of energy, moisture, and carbon between the lands, oceans, and atmosphere. The launch of EOS-AM1 and other international satellites marks a new phase of climate and global change research. Both natural and anthropogenic climate change have been studied for more than a century. It is now recognized that processes that vary rapidly in time and space-e.g. aerosol, clouds, land use, and exchanges of energy and moisture-must be considered to adequately explain the temperature record and predict future climate change. Frequent measurements with adequate resolution, as only possible from spacecraft, are key tools in such an effort. The versatile and highly accurate EOS-AM1 data, together with previous satellite records, as well as data from ADEOS, TRMM, SeaWiFS, ATSR, MERIS, ENVISAT, EOS-PM1, Landsat and ground-based networks is expected to revolutionize the way scientists look at climate change. This article introduces the EOS-AM1 mission and the special issue devoted to it. Following a brief historical perspective for an insight into the purpose and objectives of the mission, the authors summarize the characteristics of the five instruments onboard EOS-AM1. Specifically, they concentrate on the innovative elements of these five instruments and provide examples of the science issues that require this type of data
Pan, L., J. C. Gille, D. P. Edwards, P. L. Bailey, and C. D. Rodgers (1998), Retrieval of tropospheric carbon monoxide for the MOPITT experiment, Journal of Geophysical Research: Atmospheres, 103(D24), 32277–32290, doi:10.1029/98JD01828.
A retrieval method for deriving the tropospheric carbon monoxide (CO) profile and column amount under clear sky conditions has been developed for the Measurements of Pollution In The Troposphere (MOPITT) instrument, scheduled for launch in 1998 onboard the EOS-AM1 satellite. This paper presents a description of the method along with analyses of retrieval information content. These analyses characterize the forward measurement sensitivity, the contribution of a priori information, and the retrieval vertical resolution. Ensembles of tropospheric CO profiles were compiled both from aircraft in situ measurements and from chemical model results and were used in retrieval experiments to characterize the method and to study the sensitivity to different parameters. Linear error analyses were carried out in parallel with the ensemble experiments. Results of these experiments and analyses indicate that MOPITT CO column measurements will have better than 10% precision, and CO profile measurement will have approximately three pieces of independent information that will resolve 3–5 tropospheric layers to approximately 10% precision. These analyses are important for understanding MOPITT data, both for application of data in tropospheric chemistry studies and for comparison with in situ measurements.

1997

Bouchard, R., and J. Giroux (1997), Test and qualification results on the MOPITT flight calibration sources, Opt. Eng, 36(11), 2992–3000, doi:10.1117/1.601532.
The measurements of pollution in the troposphere (MOPITT) instrument is an IR radiometer that uses gas correlation spectroscopy to detect carbon monoxide and methane in the earth’s troposphere. The instrument concept was developed by the Department of Physics of the University of Toronto and it was designed, manufactured and tested by COM DEV Ltd., Canada, the prime contractor, for the Canadian Space Agency. MOPITT will be flown on the National Aeronautics and Space Administration (NASA) earth observing system (EOS) AM1 platform in mid 1998. The MOPITT instrument has eight optical channels that operate in the spectral band 2130 to 4510 cm−1 (2.2 to 4.6 μm). The radiometric calibration of the instrument is achieved by using four onboard compact high-emissivity calibration sources working in the range 285 to 500 K that were designed, manufactured and tested at Bomem, Inc., Canada. A description of these calibration sources and the results of the qualification and acceptance testing performed are presented. © 1997 Society of Photo-Optical Instrumentation Engineers.
Smith, M. W. (1997), Method and results for optimizing the MOPITT methane bandpass, Appl. Opt., 36(18), 4285–4291, doi:10.1364/AO.36.004285.
The Measurements of Pollution in the Troposphere (MOPITT) instrument will measure carbon monoxide and total column methane in the Earth’s atmosphere by means of gas-filter correlation radiometry. The center, width, and shape of the bandpass filters used to isolate the spectral channels must maximize the signal level and sensitivity to the gas of interest and minimize the interference from other absorbing gases (notably water vapor). I calculated the sensitivity to methane and the interference from other gases as a function of filter center and width. A slight shift in the filter parameters from the MOPITT baseline values increases the methane sensitivity by 20% and decreases the water vapor interference to 6% of its baseline value.

1996

Drummond, J. R., and G. S. Mand (1996), The Measurements of Pollution in the Troposphere (MOPITT) Instrument: Overall Performance and Calibration Requirements, Journal of Atmospheric and Oceanic Technology, 13(2), 314–320, doi:10.1175/1520-0426(1996)013<0314:TMOPIT>2.0.CO;2.
The Measurements of Pollution in the Troposphere (MOPITT) instrument will monitor the global concentrations of carbon monoxide and methane. It will be flown on the Earth Observing System Satellite AM-1. This paper briefly describes the scientific objectives, performance requirements, and specifications. It primarily focuses on the pre- and postlaunch calibration requirements. The hardware requirements and methodology for calibration are also discussed as well as cross-calibration and validation of MOPITT with an underlying aircraft MOPITT.

1995

Pan, L., D. P. Edwards, J. C. Gille, M. W. Smith, and J. R. Drummond (1995), Satellite remote sensing of tropospheric CO and CH4: forward model studies of the MOPITT instrument, Appl. Opt., 34(30), 6976–6988, doi:10.1364/AO.34.006976.
The Measurements of Pollution in the Troposphere (MOPITT) instrument is designed to measure tropospheric CO and CH4 from a spaceborne platform by the use of infrared gas correlation radiometers. We describe the forward model that is used as the basis for the retrieval algorithm. We present the techniques used to model the instrument and describe the radiative transfer involved in the measurement process. Calculations have been performed to assess the sensitivity of the measured radiance to changes in the target-gas concentration profiles, changes in the concentration of contaminating constituents, and to variations in the parameters that describe reflection and emission of radiation at the Earth’s surface.


Publication Count by Year

YearPublications
1995 1
1996 1
1997 2
1998 3
1999 6
2000 2
2001 2
2002 2
2003 10
2004 21
2005 16
2006 23
2007 31
2008 14
2009 25
2010 33
2011 33
2012 24
2013 39
2014 28
2015 31
2016 27
2017 27
2018 6
Total407
Compiled on 12 April 2018

UCAR/NCAR Share

                  

                  

ACOM | Atmospheric Chemistry Observations & Modeling