AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Aircraft Measurement of Isoprene-derived Organic Aerosol during the Southeast Nexus (SENEX) Campaign Using an Aerosol Mass Spectrometer
LU XU, Ann M. Middlebrook, Jin Liao, Joost de Gouw, Andre Welti, Hongyu Guo, Jack J. Lin, Aikaterini Bougiatioti, Rodney J. Weber, Athanasios Nenes, Ben H. Lee, Joel A. Thornton, John Holloway, Jessica Gilman, Brian Lerner, Martin Graus, Carsten Warneke, Michael Trainer, Nga Lee Ng, Georgia Institute of Technology
Abstract Number: 339 Working Group: Carbonaceous Aerosols in the Atmosphere
Abstract We investigated the effects of anthropogenic emissions on biogenic SOA formation through airborne measurements above the southeastern US. A suite of instruments, including an Aerodyne Aerosol Mass Spectrometer (AMS), was deployed aboard the NOAA WP-3D aircraft during the Southeast Nexus (SENEX) field campaign to characterize the chemical composition of both gas-phase and particle-phase. Measurements downwind of two coal-fired electrical generating units (Scherer and Harllee Branch), which have distinctly different NOx and SO2 emissions, provided an ideal case for examining the influence of these anthropogenic pollutants on SOA formation. We only observed substantial OA production downwind of Harllee Branch, whose NOx and SO2 emissions are 2 - 5 times higher than those of Scherer. Positive matrix factorization (PMF) analysis on the organic aerosol mass spectra suggests that the majority of OA production downwind of Harllee Branch plume is due to isoprene SOA, which likely arise from the reactive uptake of isoprene epoxydiols (IEPOX). The isoprene-derived OA factor (i.e., Isoprene-OA) correlates well with sulfate, which is consistent with results from recent ground measurement in Centreville, AL and the greater Atlanta area. The coupled effects of sulfate, particle acidity, and particle water content on Isoprene SOA formation are investigated. The time scale and favorable conditions for IEPOX uptake will also be discussed.