Abstract
Summer atmospheric coastal dynamics exert a significant influence on the levels and composition ofatmospheric particulate matter (PM) in the North-Eastern Iberian Peninsula. Summer atmospheric scenarios in this region present a high degree ofcomplexity as they are characterised by the absence ofsynoptic-scale air mass advections, the development ofbreeze circulations, enhanced photochemistry, local mineral dust re-suspension and the occurrence of African dust outbreaks. Three sampling sites were selected in Barcelona (NE Spain), an urban coastal site surrounded by complex topography. Regional dust modelling (DREAM) and high resolution meteorological modelling (MM5) were used to interpret PM levels and composition at the three sites. The results outline the effect of breeze dynamics and thermal internal boundary layer f ormation as the main meteorological drivers ofthe hourly evolution ofPM levels. Levels ofcrustal components, secondary inorganic and carbon species are higher during the night, and only the marine aerosol content is higher during the day. Nitrate levels are higher during the night due to the thermal stability on NH4NO3. Sulphate levels are higher during the night as a consequence ofthe drainage flows. Lidar measurements and model results signalled the occurrence of two African dust episodes during the study period which mainly affected the free troposphere over Barcelona. r 2005 Elsevier Ltd. All rights reserved.
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