Forecasting mesoscale winds on complex terrain using a simple diagnostic model

Abstract

The use of mesoscale models to provide an accurate representation of what the atmosphere is likely to do in the near future is one of the tools forecasters utilize to predict atmospheric variables. Because of the large amount of time and computer resources necessary to provide detailed forecasts on the mesoscale, this study looked at forecasting winds utilizing a simple diagnostic model and compared its results to a full physics model. Winds from the Fifth Generation Mesoscale Model (MM5), were run at fairly coarse grid spacings of 81, 27, and 9 kilometers and at a finer grid spacing of three kilometers. The MM5 9 kilometer results were input into the Winds On Critical Streamline Surfaces (WOOSS) model, which is a scaled down physics model designed to adjust winds to fine scale topography. A comparison of how the WOCSS model winds compared against each of the MM5 grid spacings was evaluated for an event during the period 4-7 August 1997 in the SOCAL bight region to determine if the results of the scaled down physics model were comparable to the full physics model. This experiment showed encouraging results for forecasting fine scale winds on complex topography using the simple dia nostic model