A High-Resolution Air Pollution Model Suitable for Dispersion Studies in Complex Terrain

Abstract

The development of an air pollution transport model that uses an expanding terrain-following coordinate with high resolution in analytic form near the surface and a high-order accurate transport algorithm is described. The model is designed to be internally consistent in the application of numerical methods, computationally efficient, and suitable for pollutant dispersion studies in complex terrain. The application of the time-splitting Warming?Kutler?Lomax advection scheme is examined in both rotational and deformational flows for its conservation and stability properties. It is found that the combination of this scheme with a short-wave filter makes the integration mass conserving and dispersion free. The model is applied to some hypothetical cases that represent the typical phenomena occurring over mountains. The model proves to be capable of simulating realistic planetary boundary layer structure and stability variation, hydrostatic mountain waves, thermally induced mountain?valley winds, and passive scalar dispersion over sloped surfaces reproducing features observed in field experiments.