Evolution and transport of pollutants over a Mediterranean coastal area: The influence of biogenic volatile organic compound emissions on ozone concentrations

A computational simulation of a typical sea-breeze situation and the transport and evolution of photochemical pollutants on the Spanish east coast is performed, and the influence of biogenic volatile organic compound (BVOC) emissions on the ozone concentrations formed is studied. The detailed land cover patterns and the topography of the area have been taken into account with the aid of a geographical information system. A meteorological prognostic simulation is performed as a first step, reproducing successfully the sea-breeze formation and comparing favorably with the observations. A BVOC emissions inventory is constructed for the area, which, in combination with the available anthropogenic emissions, indicates that the study area is more VOC than NOx sensitive with respect to the ozone concentrations formed. Based on the meteorological simulation and emissions inventories, a photochemical dispersion simulation is performed for two cases, with and without the BVOC emissions. The ozone evolution patterns are simulated successfully as compared with the available data. The inclusion of BVOC emissions has a minor effect on the calculated ozone concentrations, except in one case for which the morning peak ozone concentration is captured by the model only if the BVOC emissions are taken into account. This result leads to the conclusion that, under certain circumstances, BVOC can play an important role in ozone formation. The discrepancies in the modeled NOx concentrations are attributed to inaccuracies in the anthropogenic emissions inventory and suggest that the study area may be influenced by external factors that were not taken into account and require further investigation. This study was performed in the framework of the European Commission Biogenic Emissions in the Mediterranean Area (BEMA) project.