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Importance of tropospheric ClNO2 chemistry across the Northern Hemisphere
Citation:
Sarwar, G., H. Simon, J. Xing, AND R. Mathur. Importance of tropospheric ClNO2 chemistry across the Northern Hemisphere. GEOPHYSICAL RESEARCH LETTERS. American Geophysical Union, Washington, DC, 41(11):4050-4058, (2014).
Impact/Purpose:
The National Exposure Research Laboratory’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:
Laboratory and field experiments have revealed that the heterogeneous hydrolysis of dinitrogen pentoxide produces nitryl chloride and nitric acid in the presence of particulate chloride. We incorporate the heterogeneous chemistry of nitryl chloride into the hemispheric Community Multiscale Air Quality model. This heterogeneous chemistry substantially enhances nitryl chloride levels in several areas of the Northern Hemisphere and alters the composition of airborne reactive nitrogen, comprising more than 10% of monthly-mean values in some areas. Model results suggest that this heterogeneous chemistry reduces monthly-mean total nitrate by up to 25% and enhances monthly-mean daily maximum 8-hr ozone by up to 7.0 ppbv in some areas. The pathway also enhances hydroxyl radical by more than 20% in some areas which in turn increase sulfate and other secondary pollutants. The largest nitryl chloride concentrations and impacts occur over China and Western Europe, two areas in which few relevant field measurements have been made.
URLs/Downloads:
SARWARFINALFINAL_ARTICLE_HEMISPHERIC_CLNO2.PDF (PDF, NA pp, 3944.07 KB, about PDF)Geophysical Research Letters
