AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
Chemical Climatology of the Southeastern United States, 1999-2013
George Hidy, CHARLES BLANCHARD, Karsten Baumann, Eric Edgerton, Stephanie Shaw, Eladio Knipping, John Jansen, Shelley Tanenbaum, Justin Walters, Ivar Tombach, Envair
Abstract Number: 215 Working Group: Air Quality and Climate in the Southeast US: Insights from Recent Measurement Campaigns
Abstract The southeastern United States has a unique climate representing subtropical-continental conditions, with a large biogenic contribution to organic compounds affecting air chemistry. The region has experienced major growth in population and industry resulting in increased air pollution since the 1950s, and followed by a decrease after the 1990s. Experiments, including the Southeastern Organic Aerosol Study (SOAS), took place in central Alabama in June-July, 2013 for detailed study oxidant photochemistry and aerosol formation at a process level. The majority of the experiments were located in rural Centreville, AL(CTR), one of eight sites of the Southeastern Aerosol Research and Characterization (SEARCH) program. The SEARCH has a major, long-term aerometric database representing both regional and local (urban-rural) conditions from the late 1990s to 2013. The data include meteorological parameters, and concentrations trace gases and particle mass and composition, that provide a unique view of chemical climatology, as well as short-term comparisons of late spring and summer averages and hourly variations in the region. The air chemistry is characterized by sulfur, reactive nitrogen and carbon emissions in a NOx sensitive photochemical environment and summer stagnation meteorology conducive to the presence of substantial aerosol concentrations. In 2013, the pollution levels at CTR and other SEARCH sites were the lowest since full measurements began in 1999. The dataset provides a perspective for the SOAS program in terms of long-term average chemistry (chemical climatology) in a changing atmosphere. Changes in gas and particle emissions between 1999 and 2013, mediated through meteorological processes, account for the decline in pollutant concentrations at the monitoring sites in the region. These results provide an opportunity to contrast the 2013 SOAS results with temporally and spatially variable conditions in support of the development of tests for the robustness of SOAS findings.