One of the major challenges in theoretical research in atmospheric chemistry for the remaining years of this century relates to the development of accurate and reliable models of the chemical and physical processes controlling the trace composition of the atmosphere as well as its temporal and spatial variability. In recognition of this fact, the report from the Global Tropospheric Chemistry Panel of the National Academy of Sciences and the recently completed UCAR report on Global Tropospheric Chemistry: Plane for the U.S. Research Effort identified theoretical studies and modelling as one of five major research efforts needed to be undertaken in atmospheric chemistry. One of the major objectives highlighted for theoretical studies in these reports was the development of a new class of models that can couple meteorological and chemical processes. To provide a realistic simulation of the transport, transformation, and ultimate removal of selected species on a global and/or regional scale. This research project is aimed at the development and validation of a chemical transport model capable of simulation the transport, transformation, and deposition of combustion sulfur from the North American continent. Time-series measurements of radon-222, lead-210, sulfur dioxide and sulfate surface concentrations and wet deposition rates will be used to guide in the development and validation of parameterizations for boundary layer transport, wet and dry removal, and the homogeneous and heterogeneous oxidation of sulfur dioxide to sulfate. These parameterizations will then be used in the Geophysical Fluid Dynamics Laboratory (GFDL) general circulation/transport model to simulate the export and deposition climatology of anthropogenic sulfur produced on the North American continent. Of particular interest will be the fate of the approximately 75% of the North American sulfur emissions which cannot be accounted for in wet deposition over the continent.
