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Dimethylsulfide chemistry: annual, seasonal, and spatial impacts on SO_4^(2-)
Sarwar, G., J. Xing, K. Fahey, D. Kang, B. Gantt, H. Simon, AND R. Mathur. Dimethylsulfide chemistry: annual, seasonal, and spatial impacts on SO_4^(2-). ITM 2016 Conference, Crete, GREECE, October 03 - 07, 2016.
The National Exposure Research Laboratory (NERL) Computational Exposure Division (CED) develops and evaluates data, decision-support tools, and models to be applied to media-specific or receptor-specific problem areas. CED uses modeling-based approaches to characterize exposures, evaluate fate and transport, and support environmental diagnostics/forensics with input from multiple data sources. It also develops media- and receptor-specific models, process models, and decision support tools for use both within and outside of EPA.
We incorporated oceanic emissions and atmospheric chemistry of dimethylsulfide (DMS) into the hemispheric Community Multiscale Air Quality model and performed annual model simulations without and with DMS chemistry. The model without DMS chemistry predicts higher concentrations of sulfate (SO_4^(2-)) over land compared to the low concentrations over seawater. Including DMS chemistry substantially increases SO_4^(2-) concentrations over seawater and many coastal areas. It enhances the annual mean surface SO_4^(2-) by >0.8 g/m3 in some areas of the Pacific Ocean, Atlantic Ocean, Arabian Sea, and Caribbean Sea. The largest enhancement occurs in summer in which DMS chemistry increases surface SO_4^(2-)by 70% over seawater. The model without DMS chemistry underestimates the summer-time observed SO_4^(2-) in the U.S. while the model with DMS chemistry improves model performance in the U.S. coastal areas.