"Terry L. Clark and Jason K. S. Ching are the EPA Project Officers" "Sept. 1985" "EPA/600-S8-85-016."

The Advanced Statistical Trajectory Regional Air Pollution (ASTRAP) model simulates long-range, long-term transport and deposition of air pollutants, primarily oxides of sulfur and nitrogen. The ASTRAP model is designed to combine ease of exercise with an appropriate detail of physical processes for assessment applications related to acid deposition. The theoretical basis and computational structure of the ASTRAP model are described. major simplifications and assumptions incorporated in the model are discussed. The data requirements for ASTRAP simulations are monthly to seasonal time series of transport wind and precipitation analyses and an emissions inventory. ASTRAP consists of three programs: HORZ, VERT and CONCDEP. The source code is in standard FORTRAN, while the JCL is appropriate for an IBM 3033 mainframe computer. Horizontal dispersion and wet deposition statistics are calculated in HORZ. The process of turbulent vertical diffusion within the mixed layer, leakage to the free atmosphere, chemical transformation and dry deposition are calculated in VERT. The CONCDEP program combines the statistics produced by HORZ and VERT with an emissions inventory to calculate primary and secondary pollutant surface concentrations along with wet and dry depositions.