One indication of model performance is the comparison of spatial patterns of pollutants, either as concentration or deposition, predicted by the model with spatial patterns derived from measurements. If the spatial patterns produced by the model are similar to the observations in shape, location, and magnitude it can add to our confidence that the model is performing well. However, deriving spatial patterns from measured pollutant data is not always trivial. Modeling networks are spatially sparse, and frequently biased toward certain types of land use. Likewise, frequently there is measurement bias between monitoring networks. This study will compare the observed spatial patterns with those predicted by EPA's Community Multiscale Air Quality (CMAQ) model, noting any similarities and differences. We will consider sulfate (SO(sub 4)), nitrate (NO(sub 3)), ammonium aerosols (NH(sub 4)), and ozone (O(sub 3)).