Aspects of atmospheric flow and dispersion of air pollutants in a mountainous basin.

The variety of physicogeographic characteristics, the complex topography and channeling of the synoptic/regional flow are among the main reasons for the formulation of local flow patterns, and consequently for the dispersion conditions in a mountainous area. In this paper, an attempt is made to investigate the mechanisms responsible for these phenomena and to explain the dispersion of air pollutants in a mountainous basin, especially the impingement of plumes released by elevated stacks. A coupled atmospheric and Lagrangian dispersion model was used for the analysis. As it was found significant, mesoscale circulation, such as lake effects in mountainous terrain, up/downslope and valley winds, was calculated. It was proved that the plume impingement, along with pollutant recirculation, could explain the nighttime maximum air-pollutant concentrations measured in the city of Kozani.