ACOM in the News

Monday, March 2, 2020 - 11:38am
BBC CrowdScience: What’s the weirdest weather? February 28, 2020

NCAR/ACOM scientist Rebecca Buchholz contributed to a broadcast discussion of how wildfires affect weather and climate. The Carr Fire in Northern California during July-August 2018 reduced air quality across the western United States. In this broadcast, the question is posed at minute 24:00, and Rebecca's response is minutes 28:00-33:00. Listen...

Wednesday, February 19, 2020 - 9:39am
The discovery of a new sulfur molecule during the third leg of NASA ATom mission in 2017 raises many questions about our understanding of the marine sulfur cycle, which influences oceanic cloud formation. The left side of the diagram shows two primary reaction products of DMS, SO2 and MSA, and the newly discovered molecule, HPMTF. On the right, new research suggests that on average 30 percent of DMS becomes HPMTF. Image credit: Patrick Veres/NOAA.

The discovery of a novel sulfur compound during a 2017 NASA airborne research campaign will likely spur a scientific reassessment of a fundamental marine chemical cycle which drives the formation of oceanic clouds that play a key role in moderating climate, scientists said. The chemical, dubbed hydroperoxymethyl thioformate (or HPMTF), was discovered by NOAA scientist Patrick Veres while monitoring air samples being analyzed by a new NOAA Chemical Ionization Mass Spectrometer on board NASA’s instrumented DC-8 flying laboratory. The discovery was made on the third of four legs of the NASA Atmospheric Tomography campaign, known as ATom for short, in September 2017. Observations on the final leg in May 2018 confirmed the finding.

The research is published in a recent PNAS paper: "Global airborne sampling reveals a previously unobserved dimethyl sulfide oxidation mechanism in the marine atmosphere", by Patrick Veres. ACOM co-authors are Simone Tilmes, Douglas Kinnison, Rebecca Hornbrook, Alan Hills, and Eric Apel.

Read more at NOAA Research News . . .

Wednesday, February 19, 2020 - 8:33am
Catastrophic fire warning day_0069nfx, 12 November 2019, 16:53, photo by Rob Russell from Gosford, NSW, Australia at Wikimedia Commons.

ACOM Project Scientist Rebecca Buchholz talks with Connecticut Public Radio about how climate change is shaping wildfire patterns around the globe. Are severe natural disasters becoming the “new normal”? Walter Jetz, Professor of Ecology and Evolutionary Biology at Yale University, talks about the fires’ impact on biodiversity. Read more at . . .

Monday, December 9, 2019 - 9:45am
San Francisco at Sunset.jpg, by Digon3 at Wikimedia Commons.

26 scientists from ACOM will present talks and posters at the 2019 meeting of the American Geophysical Union in San Francisco, California, December 9-13. For more details about the conference program, please refer to the following schedule:


A11K-2704 (Monday, 0800 – 1220), Siyuan WangAn Online Air-Sea Exchange Model Framework for Trace Gases powered by Machine-Learning (poster)

A11V-2760 (Monday, 0800 – 1220), Forrest LaceyUsing CESM2 to isolate the modeled climate response from varying model resolutions and chemical complexity (poster)

GC11K-1112 (Monday, 0800 – 1220), Rebecca BuchholzTerra Trends: A Global Slowdown in Decreasing Atmospheric CO and the Regional Interpretation Using AOD (poster)

GC13F-1192 (Monday, 1340 – 1800), Chuck Bardeen, Influence of smoke composition on climate effects from fires following nuclear war (invited poster)

A13C-02 (Monday, 1410 – 1440), Guy BrasseurOzone Depletion and Recovery (invited talk)

IN13A-03 (Monday, 1410 – 1425), Dan ZiskinThe Evolution of the MOPITT SIPS (talk)

A14B-07 (Monday, 1730 – 1745), Siyuan WangFinding the missing reactive carbon in the atmosphere: lessons learned from acetaldehyde and implications for laboratory and field experiments (invited talk)

GC14B-07 (Monday, 1730 – 1745), Helen Worden20 years of MOPITT: What satellite observations of carbon monoxide can tell us about our changing atmosphere (invited talk)


A22A-06 (Tuesday, 1135 – 1150), Ben GaubertPerspectives on atmospheric carbon monoxide, an attempt to disentangle errors from chemistry and emissions using multiple satellites and assimilation frameworks (talk)

A23L-2963 (Tuesday, 1340 – 1800), Wenfu TangInvestigating air quality and climate impacts of fires using an interactive fire module in CESM2 (poster)

A23M-2867 (Tuesday, 1340 – 1800), Olivia Clifton, Important role for plant responses to meteorology on the cumulative stomatal flux of ozone (poster); and Primary Convener of Biosphere-Atmosphere Interactions and Atmospheric Chemistry (A23M posters, A31C oral session, A32D oral session, and A33J posters)

A23Q-2929 (Tuesday, 1340 – 1800), Guy BrasseurA world-wide Service for Air Pollution Forecasts: The MAP-AQ Project (poster)

PA23C-1177 (Tuesday, 1340 – 1800), Shima ShamsFocus Group on Climate Change (Science Communication - SWIRL)

SA23A-01 (Tuesday, 1340 – 1355), Rolando GarciaMiddle atmosphere temperature trends in the 20thand 21stcenturies simulated with the Whole Atmosphere Community Climate Model (WACCM) (talk)


A31E-01 (Wednesday, 0800 – 0815), Gabi PfisterOn the robustness of quality prediction performance assessments (invited talk)

GC31B (Wednesday, 0800 – 1000), Simone Tilmes, Primary Convener of Solar Geoengineering Benefits and Risks: Modeling, Impacts, Analogues, Engineering, Ethics, and Governance (also GC33G poster session). Session 1. Session 2.

A31E-07 (Wednesday, 0930 – 0945), Louisa EmmonsMulti-scale Predictions of Air Quality with a Variable Resolution Global Model (talk)

Exhibit Hall, Booth 505 (Wednesday, 1310 – 1330), Forrest Lacey and Becky SchwantesMulti-scale infrastructure for chemistry and aerosols (MUSICA) (Exhibit Hall presentation)

GC33G-1425 (Wednesday, 1340 – 1800), Simone TilmesSensitivity of stratospheric ozone changes with stratospheric aerosol geoengineering using the Whole Atmosphere Community Climate Model (WACCM) (poster)

A33D-07 (Wednesday, 1510 – 1525), Jim HanniganAnalysis of Long -Term Global Measurements of OCS from NDACC/IRWG Stations (talk)

A34G-02 (Wednesday, 1615 – 1630), Dan MarshThe Response to Variable Solar Forcing in WACCM Simulations for CMIP6 (invited talk)


A43G-01 (Thursday, 1340 – 1355), Alma HodzicChallenges in Modeling Organic Aerosols in the Remote Troposphere (invited talk)

A43G-04 (Thursday, 1425 – 1440), Becky SchwantesMore Explicit Alkane Chemistry Improves the Representation of Several Volatile Organic Compounds Including Methyl Ethyl Ketone in The Remote Atmosphere (talk)

A44F-05 (Thursday, 1700 – 1715), Bill RandelDeriving stratospheric age-of-air spectra from satellite water vapor measurements (talk)


A51K-2787 (Friday, 0800 – 1220), Richard NewtonUpper Tropospheric Temperature Inversions in the Indian Monsoon (poster)

A51K-2788 (Friday, 0800 - 1200), Laura PanProgress in the Asian summer monsoon Chemical and Climate Impact Project (ACCLIP) (poster)

A51K-2792 (Friday, 0800 - 1200), Shawn HonomichlTransport from the Asian Summer Monsoon Anticyclone Over the Western Pacific (poster)

U52A (Friday, 1022 – 1047), Guy BrasseurSummary of past successes of WCRP and lessons learned (invited talk)

A53P-2972 (Friday, 1340 – 1800), Mijeong ParkRecent Variability in Stratospheric Water Vapor observed by the SAGE III/ISS (poster)

A54A-05 (Friday, 1700 – 1715), Eric ApelWhat are the major volatile organic carbon influences on the remote pristine troposphere? (talk)

A54C-05 (Friday, 1700 – 1715), Mike MillsThe June 2019 Raikoke eruption: a case study for forecasting volcanic sulfate evolution (talk)

A54H-07 (Friday, 1730 – 1745), Shima ShamsHigh latitude ozone variation and their relationship to Sudden Stratospheric Warmings (talk)

Friday, September 13, 2019 - 9:49am
Point observations of ozone taken by the U.S. Environmental Protection Agency.

NCAR/ACOM is now generating high-resolution, experimental, 48-hour forecasts of air pollutants across the contiguous United States. The predictions, which are freely available online, can help decision makers anticipate episodes of unhealthy air as well as accelerate research into the factors that influence air quality. Read more at UCAR AtmosNews . . .

Thursday, August 29, 2019 - 10:49am
Aerial view of the Amazon Rainforest, photo by lubasi at Wikimedia Commons:

As the Amazon burns at a rate higher than any year measured since 2010, the environmental crisis is being watched closely by researchers in Boulder, who have devoted years of study to the long-term implications of degradation to the planet’s forests, critical for their capacity to store carbon dioxide. Read more at Daily Camera . . .

Monday, August 12, 2019 - 4:22pm
Scientists on a NASA-flown DC-8 were able to photograph and view this wildfire-produced thunderstorm. Layers of smoke in the atmosphere near the thunderstorm make the sun appear orange. (Photo courtesy of David Peterson, Naval Research Laboratory)

The phenomenon, called a pyrocumulonimbus or PyroCb, “is essentially a thunderstorm that is created or driven by a wildfire,” said David Peterson (Naval Research Laboratory).  “As we fly into this deep smoke, the light goes down, and the sun gets orange,” observed Rebecca Hornbrook, an atmospheric chemist at the National Center for Atmospheric Research (ACOM Laboratory). “It’s like a weird sepia-toned orange-ish hue.” Peterson's and Hornbrook's comments came after a research flight with the FIREX-AQ field campaign on August 8, 2019, flying out of Boise, Idaho.

Tuesday, July 30, 2019 - 7:59am
View of Denver skyline from south Table Mountain (STM). 28 September 2012. Wikimedia Commons:

Sparked by a listener question, CPR Colorado Matters interviewed ACOM Scientist Gabriele Pfister about the transport of ozone pollution from the Colorado Front Range to the mountains. Pfister has been tracking the movement of polluted ground-level ozone for years with the Boulder-based National Center for Atmospheric Research. And yes, it makes it to the mountains.

Saturday, June 29, 2019 - 8:16am
Xuan Zhang and students in MOONLIGHT chamber study.

ACOM scientist Xuan Zhang recently led a major community project in the NCAR Atmospheric Simulation Chamber. The study called MOONLIGHT (Monoterpene and Oxygenated aromatics Oxidation at Night and under LIGHTs) lasted about one month, from late May to late June 2019, and involved scientists (including many students and early-career scientists) from six different groups who visited from five different Universities (University of Washington; University of California Berkeley; University of Wyoming; University of Colorado (CIRES/NOAA); Colorado State University). The project focused on understanding the processes involved in the daytime and nighttime oxidation of a suite of volatile organic compounds (VOCs) emitted from biomass burning, and was complementary to an NSF-funded field campaign held in Summer of 2018 (WE-CAN, led by Dr. Emily Fischer, CSU). A major focus of the project was on quantifying the optical properties of the secondary organic aerosols formed in biomass burning plumes. Data characterizing the evolution of both gas- and condensed-phase composition have successfully been collected, and the exciting process of data analysis now begins.

MOONLIGHT lab work
Lab work at Atmospheric Chemistry Observations & Modeling.


The MOONLIGHT research team.

Wednesday, May 29, 2019 - 9:48am
Tucson, Arizona, with the Santa Catalina Mountains in the background. Wikimedia Commons: reported on the correlation between rising temperatures and higher ozone levels in Arizona and interviewed ACOM scientist Gabi Pfister on her 2014 study on expected changes in air quality in the U.S. by mid-century due to climate change. This study suggested that the number of high-ozone days could increase nationally as a result of increased temperatures, higher biogenic emissions, more frequent stagnation events and an increase in background ozone.

Tuesday, April 30, 2019 - 9:15am
Forrrest Lacey interviewed by 9news about Denver and ozone

Forrest Lacey, ASP Postdoc in ACOM, has been interviewed by Channel 9news about the outcomes of the recent American Lung "State of the Air" 2019 report and the health effects of exposure to ozone, short term particulates, and long term particulate, specifically as they relate to the Denver Area. The video on YouTube is titled "Why Denver's ozone problem is getting worse."

Wednesday, April 3, 2019 - 10:14am
FRAPPÉ Ozone animation

KGNU Morning Magazine has interviewed ACOM Scientist Gabriele Pfister on the air quality in the Colorado Front Range and the relative contributions from local versus transported pollution. This discussion was sparked by recent news that Colorado Governor Jared Polis and the Department of Public Health and Environment’s (CDPHE) Air Quality Control Commission rejected a push by a pro-industry group to pursue an “international contributions” exemption that would reduce the state’s responsibility under the federal Clean Air Act. You can listen to the interview at KGNU. The ACOM section begins around minute 10. (April 3, 2019)

See also this video: FRAPPÉ - Studying Ground Level Ozone in Colorado

Wednesday, February 27, 2019 - 9:30pm
Northern lights in the Arctic (courtesy: Kerri Pratt at the University of Michigan Ann Arbor)

Monday, March 4, 2019: Siyuan Wang of ASP-NCAR presented an ACOM Seminar: Halogen chemistry in the Arctic boundary layer: new chemical insights Location: FL2-1022 (large seminar room), NCAR Foothills Laboratory; 3:15 pm - refreshments, 3:30 pm - seminar. The recorded video is available on the ACOM YouTube Channel.

For a full list of upcoming and ACOM seminars, please visit the ACOM seminars page, which also includes links to past seminars and archived videos.

Northern lights in the Arctic (courtesy: Kerri Pratt at the University of Michigan Ann Arbor)

Northern lights in the Arctic (courtesy: Kerri Pratt at the University of Michigan Ann Arbor). Click for larger image.

Tuesday, January 29, 2019 - 12:59pm
Phoenix Convention Center - West Lobby - 2010-02-16. Photo by Cygnusloop99 at Wikimedia Commons:

ACOM staff joined other AMS members at the annual meeting of the American Meteorological Society in Phoenix, Arizona during 6–10 January, 2019. Although the partial government shutdown prevented some Federal employees from attending the meeting, ACOM scientists from UCAR still presented talks and posters during the week:

Mon, 11:00 – 11:15 am, Bill RandelDiagnosing Stratospheric Water Vapor Relationships to the Tropical Cold Point Tropopause (Invited talk, Session 3 Impact of Deep Convection, Volcanic Eruptions, and Large Fires on Water Vapor, Aerosols, and Ozone in the Middle Atmosphere)

Wed, 4:00 – 6:00 pm, Rebecca HornbrookGlobal Seasonal Distributions of HCN and Acetonitrile, (Poster Session 2 Atmospheric Chemistry Poster Session II)

Wed, 4:00 – 6:00 pm, Alma HodzicTowards Better Ozone Forecast over CONUS Using Improved Clouds from Rapid Refresh and Satellite Retrievals in WRF-Chem, (Poster Session 2 Atmospheric Chemistry Poster Session II)

Thurs, 8:45 – 9:00 am, Teresa CamposObservations of Major Carbon Species in Western US Wildfire Smoke Plumes during July and August, 2018, (talk, Session 11B From Combustion to Composition: New Insights into Smoke Chemistry from WE-CAN, FIREX and Other Recent Efforts—Part II)

Thurs, 10:30 – 10:45 am, Eric ApelChemical Composition and Evolution from Western Wildfires in 2018: Highlighting Results from the NCAR Trace Organic Gas Analyzer, (talk, Session 11B From Combustion to Composition: New Insights into Smoke Chemistry from WE-CAN, FIREX and Other Recent Efforts—Part II)

Thurs, 3:30 – 4:00 pm, Guy BrasseurObservations of Chemical Species in the Middle Atmosphere: Historical Evolution and New Perspectives, (Invited talk; Session 9 Future Observations of the Middle Atmosphere—Needs and Capabilities)

Thurs, 4:00 – 4:15 pm, Siyuan WangAirborne Measurements of Oxygenated Volatile Organic Compounds (OVOCs) during ATom: Implications for a Currently Unaccounted Source in the Remote Troposphere, (talk; Session 13A Atmospheric Chemistry Modeling and Observational Analysis—Part VIII)

Thurs, 4:15 – 4:30 pm, Mary BarthAnalysis of Convective Transport and Scavenging of Formaldehyde and Peroxides for Airmass Storms Observed during SEAC4RS Storms (talk, Session 13A Atmospheric Chemistry Modeling and Observational Analysis—Part VIII)

Monday, December 3, 2018 - 10:20am
Earth and Physical Sciences building - University of California at Davis. Wikimedia Commons,_Davis_-_DSC03316.JPG

Several ACOM staff were at University of California-Davis during 5-7 December 2018 to attend the Atmospheric Chemical Mechanisms Conference 2018 including Louisa Emmons, Sasha Madronich, Camille Mouchel-Vallon, John Orlando, Becky Schwantes and Geoff Tyndall. Sasha served on the ACM Program Committee. Geoff gave a talk on Thursday on ​​​​​​​Dependence of alkyl nitrate yields on structure for mid-sized alkanes. Louisa and Camille gave talks on Friday on Impact of anthropogenic and natural emissions on air quality in Korea and GoAMAZON: Exploring the Impacts of a Metropolis on Amazonian Air with an Explicit Organic Chemistry Scheme, respectively. John and Becky presented posters on Steady State Continuous Flow Chamber for the Study of Atmospheric Hydrocarbon Oxidation Chemistry under Daytime and Nighttime Conditions – Chamber Characterization and First Results and Exploring the Importance of Horizontal Resolution versus Chemical Resolution in CESM/CAM-chem, respectively.

Tuesday, August 7, 2018 - 1:30pm
Chumash Engine 802 firefighter cooling the edge du, by Kari Greer, US Forest Service. interviewed ACOM Deputy Director Gabriele Pfister on the topic of wildfires and air quality. “We’re right in the middle of climate change,” Gabi remarked, referring to the increased frequency of record-breaking heat as average temperatures continue to climb. Wildfires flare up during daytime and in a hotter climate. Government-issued warnings about unhealthy air quality will come more frequently even in communities far from those burning forests. The human result is about seven extremely unhealthy days in the western region of the United States.

Reported by Mark Kaufman on July 16, 2018.

Tuesday, August 7, 2018 - 11:35am
The June 12, 1991 eruption column from Mount Pinatubo taken from the east side of Clark Air Base. U.S. Geological Survey Photograph taken on June 12, 1991, 08:51 hours, by Dave Harlow.

Scientific American reported on ACOM scientist Simone Tilmes' experiments with geoengineering. The eruption of Mt. Pinatubo in June 1991 demonstrated that sulfur aerosols have a cooling effect by shading the earth's surface. The study found that harmful side effects (droughts, extreme rainfall) could be minimized by injecting particles into the atmosphere by airplane at 15° north latitude and 30° south. Those latitudes away from the equator provide better atmospheric mixing.

Reported by John Fialka, E&E News on July 5, 2018.

Monday, July 30, 2018 - 4:48pm
C-130 research aircraft in hangar at Rocky Mountain Regional Airport (July 11). Photo by Carl Drews.

There will be an additional plane in the air over wildfires in the northwestern United States in coming weeks, but it won't be there trying to put them out. The C-130 research aircraft flying to Boise, Idaho, from the Rocky Mountain Metropolitan Airport in Broomfield on Friday will be taking to the skies over those blazes to foster a better understanding of their impact on air quality, weather patterns and longer-term climate change.

Billed as the Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption and Nitrogen, and less awkwardly as WE-CAN, the project is led by Colorado State University, with significant support from Boulder's National Center for Atmospheric Research, and is funded by the National Science Foundation.

Read more at the Boulder Daily Camera, 19 July 2018 . . .

Thursday, April 26, 2018 - 4:47pm
DC-8 flight over the Antarctic Peninsula - May 9, 2018. Photo by Becky Hornbrook.

ACOM scientists Samuel Hall, Lizzy Asher, Kirk Ullman, Eric Apel, Alan Hills, and Becky Hornbrook are currently taking part in the ATom-4 Field Campaign. NASA reports in a press release that the DC-8 research aircraft is sampling "over 400 different gases and a broad range of airborne particles on month-long excursions from Alaska down the Pacific to New Zealand, then over to South America and up the Atlantic to Greenland, and across the Arctic Ocean". These research flights sample air over the world's oceans, where traditional land-based measurements of gases and pollutants cannot operate.

Friday, April 6, 2018 - 8:48am
Cloudscape Over the Philippine Sea, at Wikimedia Commons:

ACOM scientist Simone Tilmes was quoted in Live Science about a proposal to use salt in the upper troposphere to increase the atmosphere's reflectivity and thereby cool the earth. Unlike some other aerosols, sodium chloride (table salt) is not harmful to the earth's ozone layer. Tilmes cautions that salt often includes reactive iodine, an element that could also play a role in atmospheric chemistry.

April 6, 2018

Tuesday, March 6, 2018 - 10:14am
Image by NASA Earth Observatory at Wikimedia Commons:

The planet's ozone layer may be thinning over earth’s heavily populated areas. Robert Lee Hotz at the Wall Street Journal reports, "In a new analysis, scientists detect shrinking of the planet’s protective shield at lower levels of the stratosphere over Earth’s nonpolar regions. Part of Earth’s protective ozone shield may be thinning over the most heavily populated regions of the globe, even as an ozone hole over Antarctica continues to mend". ACOM scientist Rolando Garcia, a key developer of the WACCM model who was not involved in the published study, found the results to be convincing.

The published paper is "Evidence for a continuous decline in lower stratospheric ozone offsetting ozone layer recovery," in the scientific journal Atmospheric Chemistry and Physics.
Citation: Atmos. Chem. Phys., 18, 1379-1394, 2018.

February 6, 2018

Tuesday, March 6, 2018 - 9:31am
Image by Levi Siuzdak at Wikimedia Commons:

In a surprising study, scientists say everyday chemicals now rival cars as a source of air pollution. Chris Mooney at The Washington Post reports that "the nature of air pollution is changing dramatically as cars become cleaner — leaving personal-care products, paints, indoor cleaners and other chemical-containing agents as an increasingly dominant source of key emissions." As emissions from the transportation sector decrease, the gases emitted by household products and activities have become more significant.

The published paper "Volatile chemical products emerging as largest petrochemical source of urban organic emissions" includes contributions by ACOM and CIRES scientist Julia Lee-Taylor.
Citation: Science 16 Feb 2018: Vol. 359, Issue 6377, pp. 760-764. DOI: 10.1126/science.aaq052

February 15, 2018

Thursday, January 4, 2018 - 2:40pm
Bunk S: World on Fire. PLoS Biol 2/2/2004: e54. doi:10.1371/journal.pbio.0020054.g001

A new NASA-led study has solved a puzzle involving the recent rise in atmospheric methane, a potent greenhouse gas, with a new calculation of emissions from global fires. The new study resolves what looked like irreconcilable differences in explanations for the increase.

Tuesday, December 19, 2017 - 10:17am
Surface ozone on the Front Range. Image by UCAR AtmosNews.

A comprehensive new air quality report for the state of Colorado quantifies the sources of summertime ozone in Denver and the northern Front Range, revealing the extent to which motor vehicles and oil and gas operations are the two largest local contributors to the pollutant. The report was authored by ACOM scientists Gabriele Pfister, Frank Flocke, Rebecca Hornbrook, and and John Orlando. The Boulder Daily Camera also covered the FRAPPÉ and DISCOVER-AQ 2014 final report on October 30, 2017: Vehicles, oil and gas top sources of Front Range ozone, NCAR study shows.

Monday, October 23, 2017 - 10:55am
Different areas in Lake Tahoe side by side. Photo courtesy of Andrew Tucker.

One of the largely unanticipated impacts of a changing climate may be a decline in sunlight's ability to disinfect lakes, rivers, and coastal waters, possibly leading to an increase in waterborne pathogens and the diseases they can cause in humans and wildlife. ACOM's TUV Model was used in the study to evaluate the disinfecting power of UV light.

The news article by NCAR science writer Laura Snider highlights recent work by ACOM scientists Sasha Madronich and Julia Lee-Taylor, and Craig Williamson of Miami University in Ohio. (October 20, 2017)

Wednesday, August 30, 2017 - 11:59am
An illustration of an asteroid impacting earth. (Credit: NASA)

Tremendous amounts of soot, lofted into the air from global wildfires following a massive asteroid strike 66 million years ago, would have plunged Earth into darkness for nearly two years, new research finds. This would have shut down photosynthesis, drastically cooled the planet, and contributed to the mass extinction that marked the end of the age of dinosaurs.

The news article by NCAR science writer Laura Snider highlights recent work by ACOM scientists Charles Bardeen, Rolando Garcia, and Andrew Conley.

Tuesday, August 22, 2017 - 4:32pm
Total solar eclipse at Casper Mountain, Wyoming on August 21, 2017. Photo credit: Keon Gibson, NCAR

CASPER MOUNTAIN. — It’s nothing like a sunset. It’s cold and dark, but it’s not like nighttime, or even twilight. The moon just snaps into place over the last slivers of the sun, turning the sun into a dark hole. The only illumination — a flat, ghostly, metallic sort of light — is from peaked gossamer streamers stretching out toward the edges of the sky.

Read more by astronomy writer Lisa Grossman at Science News - August 21, 2017.

Thursday, June 29, 2017 - 3:40pm
Figure 1 of Buchholz et al 2017

Measurements of carbon dioxide from the MOPITT satellite instrument have been validated using the NDACC network of ground-based measurements. ACOM scientist Rebecca Buchholz and colleagues reported on their study of MOPITT version 6 retrievals using total column CO measurements from ground-based remote-sensing Fourier transform infrared spectrometers (FTSs). MOPITT generally shows a small bias with respect to the ground-based measurements. The ground stations are located worldwide at latitudes ranging from 80° N to 78° S, and are maintained by the Network for the Detection of Atmospheric Composition Change (NDACC).


Buchholz, R. R., Deeter, M. N., Worden, H. M., Gille, J., Edwards, D. P., Hannigan, J. W., Jones, N. B., Paton-Walsh, C., Griffith, D. W. T., Smale, D., Robinson, J., Strong, K., Conway, S., Sussmann, R., Hase, F., Blumenstock, T., Mahieu, E., and Langerock, B.: Validation of MOPITT carbon monoxide using ground-based Fourier transform infrared spectrometer data from NDACC, Atmos. Meas. Tech., 10, 1927-1956,, 2017.

Quantifying Fire Emissions & Associated Aerosol Species using Assimilation of Satellite Carbon Monoxide Retrievals
Friday, May 5, 2017 - 2:35pm

Wildfires tend to be more intense and hence costly and are predicted to increase in frequency under a warming climate. For example, the recent August 2015 Washington State fires were the largest in the state’s history. Such large fires impact not only the local environment but also affect air quality far downwind through the long-range transport of pollutants. Global to continental scale coverage showing the evolution of CO resulting from fire emission is available from satellite observations. Carbon monoxide is the only atmospheric trace gas for which satellite multispectral retrievals have demonstrated reliable independent profile information close to the surface and also higher in the free troposphere. The unique CO profile product from Terra/MOPITT clearly distinguishes near-surface CO from the free troposphere CO. Also previous studies have suggested strong correlations between primary emissions of fire organic and black carbon aerosols and CO. We used the Ensemble Adjustment Kalman Filter (DART) system to assimilate MOPITT CO profiles and MODIS Aerosol Optical Depth in the global scale chemistry-climate model CAM-chem. The ensemble technique allows inference of additional model parameters such as CO emissions, as well as emissions of aerosol species resulting from fires such as organic and black carbon.

In a case study of the August 2015 wildfires in Washington, the assimilation of MOPITT CO and MODIS AOD was used to infer corrections to the fire emissions of CO, black carbon and organic carbon using the ensemble information. The a priori emissions (based on FINN) were increased by a factor of about 3.5 for the WA fires.  Subsequent assimilation of the MOPITT CO profile can also be used to constrain the aerosol profile.


Relative average differences in Organic Carbon + Black Carbon across
North America from 20-31 Aug. 2015 compared to the Control Run

Reductions in Anthropogenic Carbon Monoxide Emissions Lead to Shorter Methane Lifetimes in the Atmosphere
Friday, May 5, 2017 - 2:27pm

About half of atmospheric carbon monoxide (CO) is from direct (CO) emissions that are due to incomplete combustion and are related to both natural (e.g. wildfires) and anthropogenic activities. The remainder of CO in the atmosphere is produced from the chemical oxidation of hydrocarbons, mainly from biogenic sources and methane (CH4). Since most of the hydrocarbons, CO, and CH4 in the atmosphere are oxidized by the hydroxyl radical (OH), the associated chemical lifetimes of these species are strongly coupled with OH. For example, a reduction in CO emissions leads to more OH and therefore a shorter CH4 lifetime, assuming CH4 emissions are the same. This means that long-lived greenhouse gases such as CH4 are linked with short-lived pollutants related to air quality. We use the NCAR coupled chemistry-climate model of the Community Earth System Model (or CESM Community Atmospheric Model with Chemistry (or CAM-Chem, to investigate the coupled nature of our chemical system through a decadal chemical reanalysis experiments. We assimilate weather observations and satellite-based measurements of CO from The Measurement of the Pollution in the Troposphere (MOPITT, across the recent decade (2002-2013) using the Data Assimilation Research Testbed (DART,

Based on these experiments, we confirm previous reports of decreasing trends in global CO burden that is mainly attributed to the reduction of CO emissions from anthropogenic sources.  However, the impact of this reduction in CO on CH4 chemical loss is not clear at this juncture. The rate of CH4 loss is dependent upon CH4 abundance and OH concentrations. It is also evident from atmospheric CH4 observations that the increase in CH4 sources leads to a positive growth rate of CH4 abundance over the recent decade and therefore leading to a positive trend in the absolute magnitude of CH4 chemical loss. As a consequence, this increase in CH4 loss leads to a positive trend in the chemical production of CO (secondary CO). From our reanalysis, we find that the other sources of secondary CO from biogenic sources (represented here as isoprene which is most important hydrocarbon emitted from vegetation), exhibits no significant trend.  Since the chemical lifetime of CH4 is inversely proportional to OH (where its main sink is CO), we infer from our analysis that during this period of long-term decline of CO abundance (mainly from changes in anthropogenic CO emissions), it is likely that we observed a reduced rate of increase in CH4 abundance and loss than in a scenario where CO emissions are the same. These results show the potential cobenefits of reducing both CO and CH4 emissions to mitigate climate and air pollution impacts.

Top panel: Monthly anomalies of globally integrated emissions of isoprene (Tg Isoprene/Month) as well as
tropospheric columns of chemical fluxes (in Tg(molecule)/Month)
estimated from the NCAR-MOPITT Reanalysis

Reference:  Gaubert, B., Arellano, A. F., Barré, J., Worden, H. M., Emmons, L. K., Tilmes, S., Buchholz, R. R., Vitt, F., Raeder, K., Collins, N., Anderson, J. L., Wiedinmyer, C., Martinez Alonso, S., Edwards, D. P., Andreae, M. O., Hannigan, J. W., Petri, C., Strong, K., and Jones, N.: 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., doi:10.1002/2016JD024863,, 2016JD024863, 2016.

Thursday, April 6, 2017 - 1:56pm

In celebration of Air Quality Awareness week, NCAR is hosting an open house featuring information and family friendly activities about air quality. Learn from experts about air quality, how we measure and research it, and how it impacts humans, plants, and animals. NCAR’s new air quality exhibit will also be featured. Bring questions and mingle with scientists and experts from NCAR, NASA, the National Park Service, the Regional Air Quality Council, the University of Colorado, Boulder County Public Health, Colorado Department of Health and Environment, GO3-The Global Ozone Project, and Ball Aerospace. Local organizations will showcase activities and resources.

ACOM Scientists will be present to discuss The Front Range Air Pollution and Photochemistry Experiment – FRAPPÉ – which aims to characterize and understand summertime air quality in the Northern Front Range Metropolitan Area (NFRMA).

This event is free and open to the public, all ages are welcome. The open house is 5 pm until 8pm on May 3, 2017 at the NCAR Mesa Lab (1850 Table Mesa Drive, Boulder, CO 80305).

Tuesday, April 4, 2017 - 10:48am

With world leaders agreeing to try to limit the increase in global temperatures, scientists at the National Center for Atmospheric Research (NCAR) are taking a look at whether geoengineering the climate could counter enough warming to help meet that goal. "One thing that surprised me about this study is how much geoengineering it would take to stay within 2 degrees if we don't start reducing greenhouse gases soon," said ACOM scientist Simone Tilmes, the lead author.

Thursday, March 23, 2017 - 10:00am
An image taken from space of smoke billowing from fires in Jambi Province on the Indonesian island of Sumatra. The false-color image was made with a combination of visible (green) and infrared light so that fires and freshly burned land stand out. (Image courtesy NASA.)

2015 wildfires linked to as many as 17,270 premature deaths

ACOM scientist Christine Wiedinmyer is a co-author of a new study into the health effects of the 2015 Indonesian wildfires. This is an excerpt from a news release issued by Newcastle University.

Wildfires in Indonesia and Borneo exposed 69 million people to unhealthy air pollution, new research has shown.

The study, published today in Scientific Reports, gives the most accurate picture yet of the impact on human health of the wildfires which ripped through forest and peatland in Equatorial Asia during the autumn of 2015.

Wednesday, July 6, 2016 - 9:56am
This animation shows the opening and closing of the Antarctic ozone hole (dark blue) in 2015. (Animation courtesy of NASA.)

Susan Solomon at MIT, along with ACOM scientists Doug Kinnison and Michael Mills, have identified the “first fingerprints of healing” of the Antarctic ozone layer, published on June 30, 2016 in the journal Science. The research was covered by BBC Science.

The research team found that the September ozone hole has shrunk by more than 4 million square kilometers — about half the area of the contiguous United States — since 2000, when ozone depletion was at its peak. They also showed for the first time that this recovery has slowed somewhat at times, due to the effects of volcanic eruptions from year to year. Overall, however, the ozone hole appears to be on a healing path.

The other paper co-authors are Diane Ivy of MIT, Ryan Neely of the University of Leeds, and Anja Schmidt of the University of Leeds.

Friday, May 13, 2016 - 10:26am
From left: ACOM scientists Sam Hall, Benjamin Gaubert, Pablo Saide, Deedee Montzka, Louisa Emmons, and Andy Weinheimer. (Photo courtesy Sam Hall, ACOM)

Between May 1 and June 12, 2016, ACOM scientists and their colleagues from NASA, U.S. and South Korean universities, and South Korea’s National Institute of Environmental Research (NIER) will collect observations from airborne labs, ships, satellites, and ground-based instruments. The campaign, which involves more than 580 researchers from 72 institutions, is called KORUS-AQ (Korea U.S.-Air Quality study).

Wednesday, February 17, 2016 - 11:58am
Asteroids passing earth - Discovery News, February 10, 2016

Discovery News: A strike by a medium-size asteroid in a forested region could change the Earth’s climate to ice-age like conditions with effects lasting for up to 10 years. Airborne soot and dust aerosols would decrease the amount of sunlight reaching the Earth’s surface, which would cause significant surface cooling, reduce precipitation and could threaten global food supplies, says ACOM's Chuck Bardeen. The impact study was carried out using the WACCM atmospheric model.

Wednesday, January 20, 2016 - 2:43pm
University of Maryland chemistry graduate student Julie Nicely provides real-time analysis of data collected off the coast of Guam. Photo credit: Ross Salawitch published an article about ACOM's CONTRAST field campaign that operated out of Guam during January and February 2014. Biomass burning in the equatorial regions of Africa and Asia causes pockets of high ozone over the western Pacific Ocean. ACOM scientist Laura Pan was a Principal Investigator for CONTRAST, and Doug Kinnison explained how NCAR's CAM-Chem model provided forecast and analysis.

Tuesday, December 8, 2015 - 4:37pm
Image credit: NASA/Steele Hill

A research paper co-authored by ACOM scientist Dan Marsh was featured in Eos. The paper describes how WACCM version 4 produces a stronger vertical circulation in the earth's atmosphere, bringing NO and NO2 down into the stratosphere over Antarctica and destroying ozone there. WACCM4 provides the basis for new studies that may increase our understanding of the sun’s impact on climate. The original paper "Simulated solar cycle effects on the middle atmosphere: WACCM3 Versus WACCM4" was published in Journal of Advances in Modeling Earth System (June 2015).

Monday, October 26, 2015 - 8:29am
Panorama of Boulder, Colorado taken from just south of Fairview High School. Photo by Hustvedt at Wikimedia Commons.

The SPARC regional workshop on “Chemical and Physical Processes in the Climate System" will be held on 9-10 November 2015 at the National Center for Atmospheric Research in Boulder, Colorado, back-to-back with the SPARC Scientific Steering Group (SSG) meeting (10-13 November 2015).

Thursday, October 22, 2015 - 10:26am
Geostationary satellite

October 21, 2015 | ACOM scientists Jerome Barre, David Edwards, and Helen Worden have demonstrated how new types of satellite data could improve how agencies monitor and forecast air quality, both globally and by region. The new satellite observations would significantly improve air pollution forecasts.

The scientists used computer simulations to test a method that combines analysis of chemistry-climate model output with the kind of data that could be obtained from a planned fleet of geostationary satellites, each of which would view a large area of Earth on a continuous basis from high orbit.

"We think the new perspective made possible by geostationary sensors would provide data that is useful for everyday air quality forecasting, as well as for early warnings about extreme events, like the effects of wildfires," said Helen Worden.

Read more at UCAR AtmosNews...

Monday, September 21, 2015 - 2:28pm
Christine Wiedinmyer

ACOM scientist Christine Wiedinmyer was quoted in an editorial in the Wall Street Journal about carbon emissions from the recent wildfires in California. She estimated that southern California fires burning for one week produced as much carbon dioxide as a quarter of the state’s monthly fossil-fuel emissions. (September 16, 2015)

Tuesday, October 22, 2019 - 6:00am
Nuclear test near Las Vegas

A hypothetical nuclear war between India and Pakistan could kill 50-125 million people in the two nations in less than a week, according to new research.

Friday, September 13, 2019 - 6:00am
Air quality map showing ground-level ozone levels across the US

NCAR has started to generate high-resolution experimental, 48-hour forecasts of air pollutants across the contiguous United States.

Tuesday, April 30, 2019 - 6:00am
Heavy traffic in New Delhi

Residents of New Delhi and nearby heavily polluted areas of northern India now have access to air quality forecasts that provide critical information for reducing their exposure to potentially unhealthy air.




ACOM | Atmospheric Chemistry Observations & Modeling