AAAR 31st Annual Conference
October 8-12, 2012
Hyatt Regency Minneapolis
Minneapolis, Minnesota, USA
Abstract View
Organic Aerosol Source Apportionment in the United States
BENJAMIN MURPHY, Kristina Wagstrom, Spyros Pandis, Carnegie Mellon University
Abstract Number: 588 Working Group: Source Apportionment
Abstract The contribution of specific sources, both anthropogenic and biogenic, to atmospheric pollution varies widely throughout space and time. The relationship between these sources and ambient receptors is complicated by variability in the sources themselves, meteorological conditions, and chemistry that occurs during the pollutants’ atmospheric lifetime. The Particulate Matter Source Apportionment Technology (PSAT) algorithm has been applied to the regional-scale CTM, PMCAMx-2008 to study the source-receptor relationships organic aerosol (OA) components, major contributors to the particulate matter (PM) mass composition.
PMCAMx-2008 treats primary organic aerosol (POA) evaporation upon dilution in the atmosphere as well as the multi-generation OH oxidation of vapor-phase organic constituents in equilibrium with aerosol phase. This phenomenon can alter the volatility of these compounds and over time have an effect on their atmospheric transport and fate. We investigate this relationship by quantifying contributions to OA loadings from local, short range, mid range and long-range sources at several receptor sites in the US. We also explore the impact of these sites as sources on the surrounding domain. Finally, we assess the average chronological age of OA mass throughout the US domain. For all of these analyses we perform model runs with and without evaporative POA and aging of OA vapors to understand the effects these assumptions have on model predictions. In previous work, a uniform representative volatility distribution was applied to OA mass from all sources. We investigate the sensitivity of our model’s results to this assumption by varying this uniformly applied distribution for a set of runs.
The analysis from this study confirms the highly regional nature of OA pollution. We also find that implementing OA aging has some effect on the average predicted particle age, but very little effect on its average predicted transport distance or extent of impact.