Numerical Simulation of Slope and Mountain Flows

Abstract Early descriptive models of mountain-valley circulations indicated that the mountain flow (i.e., the along-valley axis component out of the valley) is a true three-dimensional phenomenon. According to these descriptions, at night shallow-down slope flows on the valley sidewalls directly driven by temperature deficits near the surface produce a pooling of cool air in the valley. This deep pool of cool air in the valley compared with a much shallower surface inversion over the plains (to which the valley opens) produces a secondary flow (the mountain flow) out of the valley driven by a deep hydrostatic pressure gradient. It is this deep secondary flow which is most important to pollutant transport in deep valleys and which has not been previously investigated in a numerical model. It is the purpose of this investigation to numerically simulate the above-mentioned secondary circulation using a three-dimensional numerical model. The Colorado State University Hydrostatic Mesoscale Model-a hydrostatic,...