AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Processes Influencing the Organic Aerosol Mass during SENEX
ANN M. MIDDLEBROOK, Wayne Angevine, Jerome Brioude, Charles Brock, Joost de Gouw, Jessica Gilman, Martin Graus, John Holloway, Brian Lerner, Jin Liao, J. Andrew Neuman, Michael Trainer, Carsten Warneke, Jennifer Kaiser, Glenn Wolfe, Tom Hanisco, Frank Keutsch, Jingqiu Mao, Larry Horowitz, André Welti, NOAA ESRL
Abstract Number: 64 Working Group: Air Quality and Climate in the Southeast US: Insights from Recent Measurement Campaigns
Abstract The NOAA Southeast Nexus (SENEX) project occurred during the summer of 2013 over the southeastern United States and involved studying the interactions between natural and anthropogenic emissions at the nexus of climate change and air quality. As part of the project, a suite of instruments for aerosol and gas–phase species was deployed on the NOAA WP-3D aircraft and models were used to calculate trace gas and aerosol species in the region and along the aircraft flight tracks. Throughout the study, the measured non-refractory submicron aerosol mass was dominated by organic material (58% +/- 9%) with smaller contributions from sulfate (27% +/- 8%), ammonium (10% +/- 3%), nitrate (3% +/- 1%), and chloride (0.1% +/- 0.1%). Here we examine the influence of urban emissions on the organic aerosol (OA) mass in regions characterized by higher and lower biogenic emissions. For the air around and downwind of urban areas, OA mass is highly correlated with carbon monoxide (CO), a tracer of anthropogenic emissions as well as an oxidation product of isoprene, a biogenic species. The slope of this correlation is roughly 0.15 micrograms per standard cubic meter per ppbv, which is significantly higher than observed in prior studies. The enhancement in OA mass relative to the enhancement in CO is independent of the concentration of biogenic species. In contrast, formaldehyde enhancements are clearly higher in the presence of biogenic species in agreement with the NOAA GFDL AM3 model. Downwind from the urban areas, CO and OA were not strongly enhanced relatively to a region-wide enhancement in these species that can only be explained from the accumulation of emissions in the eastern U.S. for several days. Back-trajectories of air parcels with emissions from biogenic and anthropogenic sources will be examined to elucidate the impact of both sources on OA mass.