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“Impact of RACM2, halogen chemistry, and updated ozonedeposition velocity on hemispheric ozone predictions”
Sarwar, G., J. Xing, J. Godowitch, D. Schwede, AND R. Mathur. “Impact of RACM2, halogen chemistry, and updated ozonedeposition velocity on hemispheric ozone predictions”. Presented at NATO ITM Conference, Miami, FL, August 26 - 30, 2013.
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.
We incorporate the Regional Atmospheric Chemistry Mechanism (RACM2) into the Community Multiscale Air Quality (CMAQ) hemispheric model and compare model predictions to those obtained using the existing Carbon Bond chemical mechanism with updated toluene chemistry (CB05TU). The RACM2 enhances monthly mean ozone by 2-10 ppbv in polluted areas compared to the CB05TU while reducing mean ozone by 2-6 ppbv in remote areas. We develop an effective halogen reaction that can consume ozone over the gulfs and oceans. We modify the CMAQ deposition velocity to account for the enhanced deposition due to chemical interactions between ozone and oceanic iodide. The effective halogen reaction and enhanced deposition velocity reduce monthly mean ozone by 2-8 ppbv over water.
SARWAR_ITM_AUGUST_2013.PDF (PDF,NA pp, 574.97 KB, about PDF)
Record Details:Record Type: DOCUMENT (PRESENTATION/POSTER)
Organization:U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF RESEARCH AND DEVELOPMENT
NATIONAL EXPOSURE RESEARCH LABORATORY
ATMOSPHERIC MODELING DIVISION
ATMOSPHERIC MODEL DEVELOPMENT BRANCH