A Quasi-Lagrangian Cell Method for Calculating Long-Distance Transport of Airborne Pollutants

Abstract

The method of calculating long-distance transport of airborne pollutants presented in this article is based on the idea of following the air flowing into the emission area. The in-flowing air is divided into cells, which are then transported in the actual wind field. The cells are assumed to be able to absorb and give off pollutants and to be deformed. The influence of lateral diffusion, which will be shown to be of minor significance to long-distance pollutant transport, is considered by a smoothing procedure concurrently with the analysis of the concentration field. As examples of application, the results of SO2 transport calculation over north-western Europe for two different 3-day periods are presented. The calculated concentration values were found to be in relatively good agreement with the measured values. In studying the sensitivity of the method to changes in the mean parameters, it was deduced that the influence of these changes on the final concentrations is in general relatively easy to estimate.