1B: Analysis of ATom field campaign data

The NASA ATom mission on the DC-8 aircraft completed the final of four campaigns corresponding to the four seasons with systematic, global-scale profile sampling (see Figure 1). Led by Dr. Steven Wofsy from Harvard University, the primary goal was to examine the anthropogenic influence on the remote atmosphere including climate change impacts of methane, ozone and aerosols. ACOM scientists provided key data as a part of an expansive payload of trace gas and aerosol measurements from the:

  • Trace Organic Gas Analyzer (TOGA) for speciated measurements of a wide range of VOCs (TOGA; PI Eric Apel, Rebecca Hornbrook, and Alan Hills).
  • Charged-coupled device Actinic Flux Spectroradiometer (CAFS) for spectrally resolved down- and up-welling radiative measurements and calculations of ~40 photolysis frequencies (PI Samuel Hall; and Kirk Ullmann). Brown Carbon (BrC) remote sensing is a secondary product available from spectral analysis (see Figure 2).

 

One of the main outcomes of ATom is improvement of global chemistry model accuracy and predictive capabilities. ACOM measurement and modeling teams (including Rebecca Buchholz, Louisa Emmons, Ben Gaubert, Alma Hodzic Forrest Lacey, Jean-François Lamarque, Rebecca Schwantes, Simone Tilmes, Siyuan Wang) have contributed significantly including:

  • Implementation of biogenic ocean emissions and calculation of acetaldehyde in CAMChem.
  • CESM2 participation in an ATom model intercomparison.
  • Assessment of the production, removal, and recycling mechanisms of HOx radicals using an observationally constrained box model and CAM-Chem.
  • Evaluation of different anthropogenic and biomass burning emission inventories.
  • Newly developed online-mechanism for exploring the oceanic influences on acetone, methyl nitrate, isoprene, and organohalogens.
  • Identification of species and regions where model improvement is needed based on the ATOM observations.
  • Statistical analysis of cloud influences on photolysis frequencies based on ATom observations.

 

Both measurements and modeling outputs will be publically available in the ATom archive in accordance with NASA public data release dates.

Four deployments of the NASA DC-8 flight track sampling
Figure 1: Four deployments of the NASA DC-8 flight track sampling for ATom covering 80.6°S to 82.9°N and 164.6°E to14.3°W and 0-13 km altitude. Click for larger image.
Brown carbon (BrC) and mineral dust aerosol indicator
Figure 2: Brown carbon (BrC) and mineral dust aerosol indicator as determined by the ACOM CAFS instrument during ATom-1. A new technique exploits anomalous spectral absorption features to detect the presence of these aerosols for qualitative, real-time, remote sensing of biomass burning (BB). The data may prove useful for examination of the evolution of BrC, including chemical processing and hygroscopic growth. The induced UV changes also feed back to the photolysis frequencies affecting the chemistry. Most evident are the African biomass burning smoke plumes in the southern Atlantic and the Saharan dust plume in the north Atlantic. Click for larger image.
Sunset over Arctic sea ice during the ATom mission
Figure 3: Sunset over Arctic sea ice during the ATom mission as seen from the NASA DC-8 aircraft (Photo credit: Samuel Hall) Click for larger image.