Development and testing of a two-dimensional downslope wind model

A two-dimensional numerical model has been formulated, using a terrain-following coordinate system. By introducing an iterative procedure into the direct integration method, almost identical results to the more complicated implicit method were achieved. This allows much higher computing efficiency without compromising accuracy. By using the model, the effects of ground cooling rate, slope angle and limited slope length were determined. In order to test the robustness of the model, a field campaign to collect downslope wind data was conducted. Results from the two-dimensional model simulations agree well with the observed data. It is possible to derive some simple rules for the downslope wind, with ground cooling, slope angle and slope length as the principal inputs. These simple rules will undoubtedly be useful in practical situations when accurate numerical simulations are difficult to make.