Carmen M. Benkovitz, Seth Nemesure, Richard Wagener, and Stephen E.
Schwartz, Brookhaven National Laboratory
Carl M. Berkowitz and Richard C. Easter, Pacific Northwest Laboratory
Sulfate aerosols, especially those caused by fossil-fuel sulfur emissions, are of interest because they may offset global warming. This research summary describes a model that traces sulfur emissions from their sources; accounts for their transport by meteorological processes and their transformation by chemical reactions in the atmosphere; and predicts the resulting aerosol burdens of the atmosphere as a function of latitude, longitude, height, and time. The model was derived from the Pacific Northwest Laboratory Global Chemistry Model, modified to be driven by observation-derived meteorological data. The latitude-longitude grid is 1.125° , and the model has vertical 15 levels, extending from the surface to about 100 hPa.
Anthropogenic emissions used by the model were obtained from global and regional inventories. Gas-phase chemical reactions represented in the model are the OH-induced oxidation of SO2 to sulfate and of dimethylsulfide to SO2 and methanesulfonic acid. Aqueous-phase reactions include the oxidation of SO2 to sulfate by H2O2 and O3.
Model results include concentrations of all tracked species as functions of longitude, latitude, vertical height, and time and are captured every 6 hours. The model also permits attribution of sulfate to formation mechanism. The use of observation-derived meteorology to drive the model allows sulfate concentrations and column burdens to be compared to observations at specific times and locations. Model results closely track the magnitudes, temporal episodicity, and absolute magnitudes of the observations. Those results show:
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