A Pseudospectral Model for Dispersion of Atmospheric Pollutants

Abstract

An Eulerian model, describing the dispersion of pollutants in gases and fluids, is developed. The model is based on numerical integration of the dispersion equation, including the effect of advection, diffusion, sinks and of multiple sources. The pseudospectral method is employed for numerical integration of the dispersion equation. The model is not limited to physical problems with periodic boundary conditions, as imposed by the spectral technique. A filtering procedure prevents instabilities caused by aliasing interactions. The emphasis is placed on numerical tests relevant to air pollution studies. Pseudodiffusion is not present in this model. The error in numerical integration is brought down to a few percent of the concentration level of the pollutant. To our knowledge, the model is the most accurate Eulerian model presently available for dispersion calculations. Applications to air pollution studies are discussed. Accuracy of 19 different numerical methods is compared.