ABSTRACT
Chemical transport models (CTM) can be important tools to better understand and estimate photochemical air pollution and are quite extensively used to evaluate and forecast air quality. A photochemical modeling system should be able to reproduce daily ozone variations due to horizontal turbulence effects, vertical mixing, local removal by nitrogen oxide, and response to fast changing emissions. Most CTMs have embedded meteorological pre-processors/drivers or are coupled to one, and two types of photochemical systems are distinguished: online and offline. Photochemical simulations for continental Portugal and for two urban areas were carried out using the comprehensive air quality model (CAMx) regional CTM with the meteorological forcing coming from the meteorological model mesoscale model5. The air quality photochemical model CAMx is an offline CTM based on the integration of the continuity equation for the concentrations of several chemical species in each cell of a given three-dimensional grid domain.
