Development of an implicit air pollution model for regions of variable topography

A plane-by-plane procedure which computes pollutant concentrations on a fine grid using the interpolated mass fluxes and turbulent viscosities produced on a coarse grid by a three dimensional transient code is reported. The method allows an efficient use of computer memory at the expense of slightly increased calculation time. The performance of the method has been verified by comparison with available measurements in five monitoring stations situated in the Attica peninsula, for the day 25/5/1991. The results obtained are in a mostly acceptable qualitative agreement with measurements. The procedure can be generalized to any conservation equation which is decoupled from the flow equations.