AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Multivariate Analysis of Historical Trends in Condensed Phase Liquid Water in the Southeastern United States
THIEN KHOI NGUYEN, Annmarie Carlton, Shannon Capps, Rutgers University
Abstract Number: 217 Working Group: Air Quality and Climate in the Southeast US: Insights from Recent Measurement Campaigns
Abstract Particle-phase liquid water is a ubiquitous component of atmospheric aerosols and influences a variety of critical atmospheric processes, including light scattering, the hydrological cycle, aqueous chemistry, and particulate matter (PM) formation. Previous studies indicate that there have been major improvements in air quality in the southeast United States over the past decade due to reductions in anthropogenic emissions such as sulfur dioxide and oxides of nitrogen. Yet despite the abundance and importance of aerosol water, it is not routinely measured, and mass concentrations are not well known. Here we use the thermodynamic model ISORROPIA (v2.1) to estimate aerosol water mass concentrations from 2000-2010 in urban and rural locations using speciated ion and meteorological data from sites that are a part of the Southeastern Aerosol Research and Characterization (SEARCH) network. These estimations are coupled with aerosol scattering data from the Interagency Monitoring of Protected Visual Environments (IMPROVE) program and the Aerosol Robotic Network (AERONET) to better understand the historical trends of aerosol water in the southeastern United States in the context of improved air quality. Analysis in the region of the Southern Oxidant and Aerosol Study (SOAS) indicates decreases in aerosol water mass concentrations by 29%, 60%, and 67% over the last decade for June, July, and August, respectively. The observed trends are consistent with the hypothesis that decreases in aerosol water may explain recently noted reductions in organic mass concentrations despite no apparent decrease in biogenic volatile organic carbon precursor emissions. These results provide evidence for modulation of biogenically derived PM in the presence of anthropogenic perturbations.