Improved Air Quality Simulations during NASA's DISCOVER-AQ Texas: Incorporating Geostationary Satellite Observations

Clouds play a critical role in modulating photosysnthetically active radiation (PAR) and thereby biogenic hydrocarbon emissions, affect photolysis rates, impact boundary-layer development, lead to deep vertical mixing of pollutants and precursors, and induce aqueous phase chemistry. While numerical meteorological models have difficulty in creating clouds in the right place and time compared to observed clouds, satellite observations of clouds provide a strong constraint that can be used to correct simulated clouds and their impact on air quality simulations. One of the areas that can be improved by direct use of satellite observation is the estimates of biogenic volatile organic compounds (BVOCs). BVOCs play a critical role in atmospheric chemistry, particularly in ozone and particulate matter (PM) formation. BVOC emissions are highly sensitive to light and errors in model simulated clouds impact the amount of PAR reaching the canopy and thereby significantly impact the emission estimates.

In this study we present a new PAR product and its impact on BVOC emissions over the continental United States (with a focus on Texas). The new PAR product is generated by the University of Alabama in Huntsville (UAH) and is based on Geostationary Operational Environmental Satellite (GOES) observations. UAH PAR product was evaluated against surface observations for September 2013 (NASA's DISCOVER-AQ Houston field campaign). Several air quality simulations using WRF/CMAQ were performed and evaluated. These simulations used control and improved BVOC estimates as well as meteorological fields from WRF simulations with and without direct cloud assimilation. The results from these simulations as evaluated against DISCOVER-AQ observations will be presented.