Spatial dispersion modelling of SO2 according to the atmospheric circulation in a coastal city: Sfax (Tunisia)

Abstract

It is well-known that weather conditions are a crucial factor influencing pollution dispersion. In very industrialized and crowded coast cities, such as Sfax (on the eastern coast of Tunisia), anticyclonic situations contribute to higher levels of pollution due to atmospheric stability, and, in particular, the occurrence of strong thermal inversion layers. The present work deals with the spatial distribution of the principal pollutant (SO2) emitted by the most polluting factory in Sfax. An easy-to-implement model (based on the Gaussian model of Pasquil) has been developed to calculate spatial distributions of SO2 in the vicinity of this pollution source. This model has been applied to develop iso-concentration maps for each weather type at different times of the day. Local breeze situations, notably during the transition from diurnal to nocturnal flow, proved to be the most favourable to the formation of strong pollutant concentrations. The simulated SO2 concentrations were then overlaid on land cover maps, using a GIS, in order to identify the most vulnerable areas. Copyright © 2008 Royal Meteorological Society.