DC3 Campaign Analysis

DC3 Aircraft Missions:

A table of DC3 Missions is given in the DC3 Field Catalog:  http://catalog.eol.ucar.edu/dc3_2012/missions/missions.html

Flights to Colorado storms: May 18, June 2, June 5, June 6, June 15, June 22, June 27, June 28
Flights to W.Texas-Oklahoma storms: May 19, May 25, May 29, June 1, June 16
Flights to Alabama storms: May 21, June 11
Flights in a daytime MCS: June 11 (Falcon, GV, DC-8 all sampled this storm)
Overflight of MCS and profile behind MCS: May 30
Flights Downwind of storms: May 26 (from OK storm), May 30 (from OK storm), June 7 (from CO storm), June 17 (from TX/OK storm), June 23 (from CO storm)
MCS photochemical aging: June 21
Falcon flights: May 29, May 30, June 6, June 8, June 11, June 12, June 14
Seasonal transition in Gulf of Mexico: June 25
Biomass Burning: May 14, May 26, … June 22, June 25 and several Falcon flights
Source Characterization: May 18, May 26, June 1, June 7, June 30

 

DC3 Topics

A list of individual DC3 investigator studies is given in the Google docs spreadsheet at this link.

For column 2 the DC3 topics are described below. A list of DC3 cases is given below with a link to the Field Catalog where more information can be found.

  1. Quantify tracer transport from the boundary layer (BL) to the upper troposphere (UT).

    Inert tracers are transported primarily to the upper troposphere within 3-5 km of the tropopause in shear-driven storms, such as those found in Colorado and Oklahoma, and can be used to determine the maximum outflow altitude, which will be different than cloud top height, the level of neutral buoyancy, and the maximum ice content altitude. These same inert tracers are transported throughout the free troposphere in airmass thunderstorms, more common in the southeastern U.S. This implies that shear-driven thunderstorms contribute more to UTLS chemistry, ozone production, and cross tropopause transport than airmass thunderstorms.
  2. Estimate scavenging of soluble tracer species.

    In the anvil and near the convective cores, soluble species, e.g. HNO3, H2O2 and CH2O, will be depleted compared to their background UT mixing ratios because ice scavenges the dissolved species in cloud water within the convective core. Furthermore, because of the short time an air parcel is in contact with liquid water and the high updraft speeds, transport of soluble species to the UT will be more efficient in the high plains (Colorado) storms compared to the storms in northern Alabama. The warmer cloud bases and greater moisture contents in Oklahoma and Alabama have larger liquid water regions resulting in more efficient scavenging of soluble species.
  3. Production of nitrogen oxides (NOx) from lightning.

    The contribution of lightning to NOx concentrations in the anvil, and subsequently in the upper troposphere, depends on overall flash rates and aggregate channel lengths at heights extending from just above the melting level to the uppermost region of the convective core. The amount of NOx produced by a cloud-to-ground flash is on average roughly equivalent to that produced by an intracloud flash.
  4. Lightning flash rate correlations with storm parameters.

    The flash rates of a storm are proportional to the volume of updrafts greater than 10 m/s in the -10 ̊C to -40 ̊C layer and to storm graupel echo volume. Cloud-to-ground lightning occurrence usually follows the occurrence of precipitation in the 0 ̊C to -10 ̊C layer after graupel has appeared in this region or higher regions. Conversely, cloud-to-ground lightning occurrence is inhibited in storms that produce little precipitation.
  5. Inverted polarity lightning.

    Storms that produce inverted-polarity IC flashes in the upper part of storms and inverted- polarity CG flashes are those in which a large fraction of the adiabatic liquid water profile is realized as cloud liquid in the mixed phase region.
  6. Chemistry in the anvil.

    The chemical composition of the convective outflow within and near the visible anvil will be stratified into a top layer with high radiation fluxes accelerating radical chemistry, and a lower layer with low radiation fluxes and near nighttime-like radical chemistry.
  7. 0-24 hours after convection.
  8. Seasonal transition of the UT chemical composition.

    Survey flights at the end of June from the central U.S. to the northern Caribbean will find the greatest UT ozone and NOx mixing ratios above the Gulf of Mexico and Florida. This analysis includes any aged UT air, especially air masses under the high pressure ridge experienced over the central US.
  9. Aerosol measurements
  10. Halogens. As part of DC3, we will include measurements of long and short-lived organic halogen source gases and the amount of at least one inorganic bromine and chlorine containing compound (e.g. BrO and HCl) in order to calculate inorganic halogen amount and the partitioning among various reactive and reservoir species.
  11. will characterize the aerosol number and mass concentrations in the inflow and outflow regions of the storms. These aerosol measurements can be connected to the ice concentration measurements in the anvil of the storms. Aerosol optical properties and composition will be analyzed to evaluate the effect of thunderstorms on aerosols.
  12. Biomass Burning.
  13.  
  14. Source Characterization includes characterization of the oil and gas wells in Colorado, Texas, and Oklahoma, biomass burning, biogenic VOC emissions, and other anthropogenic sources (cities, feedlots, factories).
  15. Other.


  16. In sampling the convective plume 0-24 hours after convection, we expect to find that 8-12 ppbv ozone will be produced per day due to high NOx and enhanced concentrations of HOx precursor species. The ozone production will vary in a complex nonlinear fashion depending on the NOx and VOC abundance transported to the anvil from the boundary layer and the amount of NOx produced by lightning. This includes the MCS photochemical aging study on June 21, 2012.