AAAR 35th Annual Conference October 17 - October 21, 2016 Oregon Convention Center Portland, Oregon, USA
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Sources and Evolution of Wintertime Organic Aerosol in the Northeastern US
JASON SCHRODER, Pedro Campuzano-Jost, Douglas Day, Nicola Blake, Alan Hills, Rebecca Hornbrook, Eric Apel, Andrew Weinheimer, Teresa Campos, Viral Shah, Kelsey Larson, Jaegle Lyatt, Jose-Luis Jimenez, CIRES, University of Colorado, Boulder
Abstract Number: 27 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract Most recent aircraft field studies have been conducted in summer, and thus wintertime aerosol sources and chemistry are comparatively poorly understood. The WINTER aircraft campaign was a recent field experiment to probe the sources and evolution of gas pollutants and aerosols in Northeast US urban and industrial plumes during the winter. A highly customized Aerodyne high-resolution aerosol mass spectrometer (AMS) was flown on the NSF/NCAR C-130 to characterize submicron aerosol composition and evolution. Thirteen research flights were conducted covering a wide range of conditions, including rural, urban, and marine environments during day and night. Organic aerosol (OA) was an important component of the submicron aerosol in the boundary layer. The fraction of OA measured during WINTER was smaller (35-40%) than in recent US summer campaigns (~60-70%). The distribution of OA oxygenation (O:C) is broader when compared to other recent summer and spring time studies, and shows a larger fraction of less oxygenated OA, suggesting more primary emission are present during winter. However, when compared to a recent GEOS-Chem version the measured wintertime OA is substantially more oxidized. A case study of urban outflow from NYC is used to investigate wintertime evolution of OA. Based on positive matrix factorization analysis; the NYC OA outflow has a substantial amount of primary biomass burning OA (~50%), a relatively constant concentration of hydrocarbon like OA (ie primary urban), when dilution is accounted for. A rapid increase in oxidized OA (OOA, a surrogate for secondary OA) is observed with distance from NYC, indicating that the SOA production from polluted sources is faster than expected in wintertime.