On the prediction of the wind field in complex orography for accident analysis

摘要

The work presented in this paper is part of a program to develop a method for stategic planning during industrial emergencies. The paper discusses the simulation of the wind field, for use in pollutant dispersal predictions, over a mountainous coastal egion, 100 by 100 km, in north-west Wales, UK. A simple null-divergence code (AVACTA II) has been modified to allow initialization in the absence of vertical profiles of wind. The input to the simulations is limited to data that is readily available in real time, i.e.ground level wind observations and the geostrophic wind, calculated from surface pressure charts. The initialization of the wind field is of paramount importance for the accuracy of the solution obtained after the minimization of the divergence. Simulations are initialized using the geostrophic wind only, and also with the inclusion of ground level observations. The results are compared to simulations previded by a numerical model that solves the non-linear equations of motion and thermodynamics.