Book Description

This report documents the culmination of a three-year development and testing effort on a two-dimensional (x-y plane) surface-layer windflow model for complex terrain. The model was acquired from the U.S. Army Atmospheric Sciences Laboratory (ASL) at White Sands, New Mexico in 1984. The version of the model described in this report has been adapted to run using real time data on both the Zenith-100 and IBM-compatible Zenith-248 computers. The model accepts input of a single surface observation (or forecast) of wind, temperature, and cloud cover, and uses this information along with terrain information and the date/time to diagnose the surface-layer stability. The model then performs a variational analysis of the windfield, adjusting the winds through a relaxation technique until the windfield conforms to effects of topography, stability, ambient flow conditions, and mass continuity. The model is designed to produce high-resolution wind analyses, typically running on domains on the order of 10 X 10 km, with horizontal grid spacing of 100 to 200 m. We present an overview of potential military and nonmilitary uses for the model, and describe the relevant physics and computer architecture of the model and its two utility plotting routines. A user's guide, included here as Section 4, is primarily aimed at providing operational users such as forecasters some guidelines for using the model and interpreting the output. Finally, we present the results of an operational test of the model in support of Army Special Forces operations at Ft. Devens, Massachusetts. The test results illustrate the model's potential as a tactical weather support tool for low-level aviation and paradrop activities.