Performance assessment of a long-term photochemical modelling system

Abstract

Modelling systems can represent suitable tools to study photochemical pollution and to analyse and assess appropriate emissions reduction strategies. Since high tropospheric ozone concentrations are quite usual in Mediterranean areas, causing adverse effects on human health, materials and ecosystems, an integrated photochemical pollution modelling system has been developed and applied to Italian regions; seasonal simulations have been performed to estimate useful indicators of ozone exposure, as AOT indexes. A particular integrated system, including a 3D meteorological model (CALMET), a flexible emission evaluation model (POEM) and two photochemical transport models (CALGRID and STEM-FCM), has been applied to a Northern Italy domain including the whole Regione Lombardia, characterised by complex terrain, high urban and industrial emissions and a close road network. The simulation period was the sunny season May–July 1996. The model skill in simulating the long-term dynamics of pollutants in the atmosphere has been assessed by means of performance indicators and graphical tools, estimated for a restricted number of monitoring stations, selected as representative of different orographic and emissive features. A performance assessment and comparison referred to ozone estimates are presented for the two photochemical models taken into account.