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A Comparison between 2010 and 2006 Air Quality and Meteorological Conditions, andEmissions and Boundary Conditions used in Simulations of the AQMEII-2 North American Domain
Citation:
Stoeckenius, T., C. Hogrefe, J. Zagunis, T. Sturtz, B. Wells, AND T. Sakulyanontvittaya. A Comparison between 2010 and 2006 Air Quality and Meteorological Conditions, andEmissions and Boundary Conditions used in Simulations of the AQMEII-2 North American Domain. ATMOSPHERIC ENVIRONMENT. Elsevier Science Ltd, New York, NY, 115:1-756, (2015).
Impact/Purpose:
The National Exposure Research Laboratory′s (NERL′s)Atmospheric Modeling Division (AMAD) conducts research in support of EPA′s mission to protect human health and the environment. AMAD′s research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the Nation′s air quality and for assessing changes in air quality and air pollutant exposures, as affected by changes in ecosystem management and regulatory decisions. AMAD is responsible for providing a sound scientific and technical basis for regulatory policies based on air quality models to improve ambient air quality. The models developed by AMAD are being used by EPA, NOAA, and the air pollution community in understanding and forecasting not only the magnitude of the air pollution problem, but also in developing emission control policies and regulations for air quality improvements.
Description:
Several participants in Phase 2 of the Air Quality Model Evaluation International Initiative (AQMEII-2) who are applying coupled models to the North American domain are comparing model results for two years: 2006 and 2010. While a key difference of interest between these two years from a modeling perspective are the large reductions in emissions of NOx (21%) and SO2 (36%) - which occurred mostly in the eastern U.S - and lower emissions from western wildfires, meteorological conditions also differed significantly between these two years. Differences in meteorological conditions both confound the impact of emission reductions on ambient air quality and provide an opportunity to examine how models respond to changing meteorology. In addition to warmer summer temperatures, conditions in the eastern U.S. summer of 2010 were characterized by less precipitation than in 2006, while western portions of the U.S. and Canada were much cooler in 2010 due to a strengthening of the thermal trough over the Southwest and associated onshore flow. Summer ozone levels in many portions of the Northeast and Midwest were largely unchanged in 2010 despite reductions in precursor emissions. Normalization of the ozone trend to account for differences in meteorological conditions, including warmer summer temperatures in 2010, shows that the emission reductions would have resulted in lower ozone levels at these locations if not for the countervailing influence of meteorological conditions. Winter mean surface temperatures were generally above average in 2006 whereas below average temperatures were noted in the Southeast and northern plains in 2010, consistent with a greater frequency of cold arctic air outbreaks. A daily synoptic typing analysis based on sea-level pressure patterns confirmed that the pattern associated with these cold weather events occurred much more frequently during 2010 whereas the predominant pattern associated with above average temperatures in the central and northeastern U.S. during the winter was more common in 2006. In general, differences in emissions and meteorological conditions between 2006 and 2010 in North America appear to be consistent with changes in observed air quality. Two potential inconsistencies were noted which warrant further investigation: 1) an increase in particulate nitrate during the winter in the Midwest despite lower emissions of NOx and 2) lower than expected SO2 reductions in the Southeast during the winter.
URLs/Downloads:
FINAL FINAL STOECKENIUSETAL_.PDF (PDF, NA pp, 1299.219 KB, about PDF)Atmospheric Environment
