9526184 Sillman Recent measurements of tropospheric trace species were performed as part of the North Atlantic Regional Experiment (NARE) at remote marine locations along the North Atlantic coast. These species include ozone; which impacts human health, agricultural crops and ecosyqtems; hydroxyl radical, which controls tropospheric lifetimes of a wide range of species, including methane and halogenated hydrocarbons; and nitrogen oxides. These measurements provide important information about the chemistry of polluted continental air masses exported to the Atlantic Ocean. Preliminary results suggest that significant removal of reactive nitrogen occurs as continental air travels over the ocean, possibly associated with fog events. This project will investigate the export of chemically reactive species using a combined continental- and urban/regional-scale model developed by the PI. The urban/regional-scale model represents the photochemical evolution of urban plumes transported over water and includes the impact of vertically stratified circulation over water. The model chemistry will be enhanced to include aqueous reactions, and representation of fog events. This project could identify conditions that lead to the removal of nitric acid and PAN and quantify removal rates for these reactive nitrogen-containing species. Comparison of the model results with the NARE measurement data will be performed to assess and refine the model's ability to simulate chemical processing and transport of polluted continental air masses as they travel over the Atlantic Ocean.
