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:Examination of Sulfate production by CB05TU, RACM2 & RACM2 with SCI initiated SO2,oxidation in the Northern Hemisphere"
Citation:
Sarwar, G., J. Godowitch, K. Fahey, J. Xing, David-C Wong, Jeff Young, S. Roselle, AND R. Mathur. :Examination of Sulfate production by CB05TU, RACM2 & RACM2 with SCI initiated SO2,oxidation in the Northern Hemisphere". Presented at Presentation at the CMAS Conference, Chapel Hill, NC, October 28 - 30, 2013.
Impact/Purpose:
The National Exposure Research Laboratory (NERL) Atmospheric Modeling and Analysis Division (AMAD) conducts research in support of EPA mission to protect human health and the environment. AMAD research program is engaged in developing and evaluating predictive atmospheric models on all spatial and temporal scales for forecasting the 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:
We employ the Community Multiscale Air Quality model to examine tropospheric sulfateproduction in the northern hemisphere using the Carbon Bond 2005 chemical mechanism withupdated toluene chemistry (CB05TU) and the Regional Atmospheric Chemistry Mechanism(RACM2) without and with sulfur dioxide (SO2) oxidation by Stabilized Criegee Intermediate(SCI). CB05TU predicts the lowest sulfate concentrations among the three mechanismsexamined in this study. RACM2 enhances sulfate concentrations compared to those obtainedwith CB05TU due primarily to enhanced SO2 oxidation by increased hydroxyl radical. SO2oxidation by SCI further enhances sulfate compared to those obtained without the SCI chemistry.The gas-phase oxidation pathway produces the highest contribution to predicted sulfate andhydrogen peroxide oxidation produces the second highest contribution in RACM2. Predictionsobtained with RACM2 augmented with SO2 oxidation by SCI are the highest among the threemechanisms and compare best with the observed data.