Seasonal NH sub(3) Emissions for the Continental United States: Inverse Model Estimation and Evaluation

Seasonal NH sub(3) emissions for the continental United States are investigated. The bottom-up an top-down emission information is combined with the most recent 2001 USEPA National Emission Inventory (NEI) to construct a best prior estimate of seasonal NH sub(3) emissions. These emission estimates are then used in an annual 2001 USEPA Community Multiscale Air Quality (CMAQ) model simulation for the continental United States. A key objective of this study is to evaluate these prior NH sub(3) emission estimates and test the top-down inverse modeling method for a different year and a larger modeling domain than used previously. Inverse modeling results suggest that the prior NH sub(3) emission estimates must be increased in the summer and decreased in the winter, while results for the spring and fall are questionable due to precipitation prediction biases.