On the Impact of Valley/ridge Thermally Induced Circulations on Regional Pollutant Transport

The impact of thermally induced valley/ridge circulations on the regional-scale transport of pollutants is examined using a modeling approach. The approach consists of applying a numerical meteorological model which provides the wind and turbulence fields used as input to a Lagrangian dispersion model. A variety of generic simulations were performed. Results indicate a significant effect of the induced local flows and the thermal stratification on the regional-scale transport. Both the time of the day in which the cross valley/ridge transport occurs and the season of the year are found to be crucial in determining the magnitude and form of the alterations. Conceptual general~tions of the model results are presented. Key word index: Thermally-induced circulations, local circulations and their effect on regional transport, numerical model transnort evaluations, dispersion modeling, mesoscale thermally forced circulations and their effect on regional transport.