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Role of photoexcited nitrogen dioxide chemistry on ozone formation and emission control strategy over the Pearl River Delta, China
Zhang, R., G. Sarwar, J. Fung, AND A. Lau. Role of photoexcited nitrogen dioxide chemistry on ozone formation and emission control strategy over the Pearl River Delta, China. Atmospheric Research. Elsevier Science BV, Amsterdam, Netherlands, 132133:332-344, (2013).
The National Exposure Research Laboratory′s (NERL′s) Atmospheric Modeling and Analysis 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.
A new hydroxyl radical formation pathway via photo-excited nitrogen dioxide chemistry is incorporated into a chemistry-only box model as well as a 3D air quality model to examine its potential role on ozone formation and emission control strategy over the Pearl River Delta region in China. While the box model results suggest that the photo-excited nitrogen dioxide chemistry can substantially enhance ozone at high NOx and VOC concentrations, results of 3D air quality model show only a moderate increase in ozone. Though the photo-excited nitrogen dioxide chemistry enhances ozone by a maximum of 10 ppbV over the urban area in the vicinity of abundant NOx and VOC concentrations, its typical enhancements range between 2 and 3 ppbV. It enhances ozone within the entire planetary boundary layer under conditions featured in weak synoptic wind, abundant water vapor and strong land–sea breeze circulation. No significant improvement in model performance statistics for ozone is found with the photo-excited nitrogen dioxide chemistry. The photo-excited nitrogen dioxide chemistry marginally changes ozone responses to NOx and VOC emission controls.