Comparison of two- and three-dimensional atmospheric dispersion models

In most of the atmospheric dispersion codes the diffusion in the direction of the wind is neglected, thus reducing the problem to a two-dimensional dispersion in a plane perpendicular to the wind direction. Two- and three-dimensional models are compared with respect to their effects on the concentration of pollutants at ground level. The accuracy of the simpler two-dimensional model for most of the cases of interest is demonstrated. However, care must be taken in the use of the simpler model for short distances and for time dependent calculations. (author)