The U.S. Environmental Project Agency is sponsoring the Complex Terrain Development program, a multi-year integrated effort to develop, evaluate, and refine practical plume dispersion models for calculating ground-level air pollutant concentrations that result from large emission sources located in mountainous terrain. At the present time, slightly more than halfway through the effort, a scientific assessment document on the status of complex terrain dispersion models for regulatory application has been prepared to inform potential users of the current availability of complex terrain dispersion models, and to describe the future products of the Complex Terrain Model Development program. This assessment document summarizes the meteorological phenomena of importance to complex terrain modeling and describes currently available modeling techniques. Results from selected model evaluation studies and from related fluid modeling simulations are also presented. Based on this current state of model development, suggestions are presented for model improvements and for current and future research needs. The assessment document concludes with a summary of major findings and associated conclusions pertinent to the topic of complex Terrain dispersion modeling.

"November 1984." "EPA-600/3-84-103."