Interpreting Aerosol Sources and Seasonality over the Southeast United States with the GEOS-Chem Model: Lessons from the SEAC4rs Campaign

Sungshik Kim1, Daniel J Jacob2, Jenny A Fisher3, Katherine Travis4, Lei Zhu5, Karen Yu6, Robert Yantosca6, Melissa Payer Sulprizio6, Jose L Jimenez7, Pedro Campuzano-Jost8, Jack E Dibb9, Karl D Froyd10, Jin Liao11, Johnathan W Hair4, Carolyn F Butler12, Marta A Fenn13 and Christine Wiedinmyer14, (1)Harvard--EPS Hoffman, Cambridge, MA, United States, (2)Harvard University, School of Engineering and Applied Sciences, Cambridge, United States, (3)University of Wollongong, Centre for Atmospheric Chemistry, School of Earth, Atmospheric and Life Sciences, Wollongong, NSW, Australia, (4)NASA Langley Research Center, Hampton, VA, United States, (5)Harvard University, John A. Paulson School of Engineering and Applied Sciences, Cambridge, United States, (6)Harvard University, Cambridge, MA, United States, (7)Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado Boulder, Boulder, United States, (8)University of Colorado Boulder, Department of Chemistry and Cooperative Institute for Research in Environmental Sciences, Boulder, United States, (9)University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Durham, United States, (10)NOAA/CIRES, Boulder, CO, United States, (11)NOAA Boulder, Boulder, CO, United States, (12)Science Systems and Applications, Inc., Lanham, MD, United States, (13)Coherent Applications, Inc. -Psionic, LLC, Hampton, United States, (14)University Corporation for Atmospheric Research, Boulder, CO, United States
Abstract:
The factors driving the aerosol seasonal cycle in the Southeast United States is an open problem in atmospheric chemistry. Satellite studies show strong seasonality of aerosol optical depth (AOD) peaking in summer and collocated with biogenic emissions, suggesting strong organic aerosol (OA) influence. In contrast, surface station measurements show a weaker seasonal cycle, primarily driven by sulfate. Previous studies have attempted to reconcile this apparent disconnect between the satellite and surface data by hypothesizing various sources of aerosol aloft. Here we interpret data from the SEAC4RS aircraft campaign in 2013, together with EPA AQS surface station measurements and MODIS and AERONET AOD, in a high-resolution version of the GEOS-Chem chemical transport model (CTM) with detailed ozone-aerosol chemistry. We use the aircraft observations to examine the consistency between the satellite and surface aerosol data. We quantify the contributions of anthropogenic, biogenic, and open fire sources to the different aerosol species, and examine relationships between species and their precursors as constraints on emissions and chemistry. This provides new insights on the factors that control aerosol concentrations, seasonality, and long-term trends in the Southeast US.
Back to: Atmospheric Gas-Phase and Aerosol Chemistry over the Southeastern United States III