Effects of Urban and Biomass Burning Sources on Downwind Aerosol and Ozone Distributions: Regional Scale Simulations Combined with Airborne Remote Sensing Measurements during TCAP and SEAC4RS and their Link to Spaceborne Observations

Abstract:

Airborne remote sensing measurements provide a valuable tool in constraining regional models, and a way to assess effects of source emissions and long-range transport on atmospheric composition.

In this work we combine airborne and space-borne remote sensing measurements of AOD and ozone with trajectory and regional models to 1) study the effects of emissions and long-range transport on atmospheric composition of downwind receptor areas, and 2) explore signatures of these effects observable from satellite sensors. Our study focuses on the East and West Coast of the US during the 2012 TCAP (Two Column Aerosol Project) summer and the 2013 SEAC⁴RS (Studies of Emissions, Atmospheric Composition, Clouds and Climate Coupling by Regional Surveys) campaigns. We define two main receptor regions: (1) ocean-column offshore of Cape-Cod during TCAP and (2) downwind area from Yosemite Rim fires over Nevada and Idaho during SEAC⁴RS. For each region, we perform forward trajectory simulations from two major emission sources - fires and urban/industrial centers - using FLEXPART Lagrangian analysis driven by WRF meteorology to assign their relative importance. We then compare WRF-Chem simulated column AOD, extinction profiles and ozone amounts for each receptor area with the airborne measurements made by the 4STAR (Spectrometer for Sky-Scanning, Sun-Tracking Atmospheric Research), as well as with space-borne measurement by MODIS and OMI. Finally, we investigate differences in total AOD, vertical distributions (when available), and ozone levels as they relate to source attribution, spatial averaging, and to modeling and measurement uncertainties.