MODELING OF PHOTOCHEMICAL POLLUTION IN ATHENS, GREECE - APPLICATION OF THE RAMS-CALGRID MODELING SYSTEM

The causes of the poor air quality in Athens, Greece during the severe episode of 25-26 May 1990 has been studied, using a prognostic model (RAMS) and a three-dimensional Eulerian air quality model (CALGRID). The modeling effort indicates that the main urban area of Athens exhibited high concentrations of nitrogen oxides, the main sources of which are automobiles, while the NNE suburban area exhibited high ozone concentrations, the product of photochemical activity of the primary pollutants that were transported by the sea-breeze. The application of the models also demonstrated the need for an accurate emission inventory for improved predictions of the pollutant concentrations. It was also found that a 50% reduction of the nitrogen oxide emissions will increase the ozone levels in the downtown area substantially.