Prediction Methods for the Dispersal of Atmospheric Pollutants in Complex Terrain

摘要

A more or less unified approach is presented for the approximate analysis of neutral and stable flows over complex terrain, and the dispersion of atmospheric pollutants in these flows. For the most part, the flows are analyzed by dividing them into an inner, a middle and an outer region, which are then matched. A number of approximate and exact solutions for these various regions are presented. Particular attention is given to stably stratified flow over hills of low to moderate slope, neutral flow over groups of such hills, strongly stratified flow around three-dimensional hills and groups of hills, and flow behavior on lee slopes and in wakes and valleys in the case of two-dimensional hills. Diffusion is handled by a Gaussian plume method corrected for local straining and turbulence production along the trajectory, and for the presence of the surface. Dispersion results are presented for flows with shear. The dispersion problem in and near the separated regions downwind of hills is discussed.