||Environmental Protection Agency, Research Triangle Park, NC. Atmospheric Sciences Research Lab. ;Atmospheric Environment Service, Downsview (Ontario). ;Analytical Sciences, Inc., Research Triangle Park, NC. ;Ottawa Univ. (Ontario).
The International Sulfur Deposition Model Evaluation (ISDME) project, jointly conducted by the U.S. Environmental Protection Agency and Atmospheric Environment Service of Environment Canada, assessed the performance of eleven linear chemistry atmospheric models in predicting amounts of sulfur wet deposition. Standardized model input data sets were distributed to the participating modelers, who later submitted seasonal and annual 1980 model predictions of dry/wet deposition and air concentrations of sulfur dioxide and sulfate at up to 66 sites across eastern North America. The models were evaluated in an operational mode using new, more rigorous approaches, as well as the more conventional distribution statistics recommended by the American Meteorological Society. The new approaches focused on the ability of the models to replicate features of the spatial patterns of sulfur wet deposition, as determined by an interpolation technique known as kriging. The technique quantified the uncertainties in the observations which were used in the evaluation process to identify areas where interpolated predictions were statistically significantly different from the interpolated observations. To supplement the evaluation, predictions of dry deposition amounts and air concentrations of each model were intercompared to identify apparent peculiarities. Finally, a scoring system based on criteria for six model performance measures was devised to compare seasonal, annual and overall performances of the models. Three clusters of models, each with similar overall scores, were identified.