Atmospheric Chemistry and Physics www.atmos-chem-phys.net 1680-7316 1680-7324 9 21 2009 10.5194/acp-9-8265-2009 http://www.atmos-chem-phys.net/9/8265/2009/ http://www.atmos-chem-phys.net/9/8265/2009/acp-9-8265-2009.html http://www.atmos-chem-phys.net/9/8265/2009/acp-9-8265-2009.pdf 8265 8282 2009-11-03 Aerosol characterization in Northern Africa, Northeastern Atlantic, Mediterranean Basin and Middle East from direct-sun AERONET observations S. Basart sara.basart@bsc.es C. Pérez E. Cuevas J. M. Baldasano G. P. Gobbi Earth Sciences Department, Barcelona Supercomputing Center-Centro Nacional de Supercomputación, BSC-CNS, Barcelona, Spain Izaña Atmospheric Research Center, Meteorological State Agency of Spain (AEMET), Santa Cruz de Tenerife, Spain Environmental Modelling Laboratory, Technical University of Catalonia, Barcelona, Spain Inst. of Atmospheric Sciences and Climate, ISAC-CNR, Rome, Italy now at: The Earth Institute at Columbia University, NASA Goddard Institute for Space Studies and The International Research Institute for Climate and Society, New York, USA We provide an atmospheric aerosol characterization for North Africa, Northeastern Atlantic, Mediterranean and Middle East based on the analysis of quality-assured direct-sun observations of 39 stations of the AErosol RObotic NETwork (AERONET) which include at least an annual cycle within the 1994–2007 period. We extensively test and apply the recently introduced graphical method of Gobbi and co-authors to track and discriminate different aerosol types and quantify the contribution of mineral dust. The method relies on the combined analysis of the Ångström exponent (α) and its spectral curvature &delta;&alpha;. Plotting data in these coordinates allows to infer aerosol fine mode radius (<i>R</i><sub><i>f</i></sub>) and fractional contribution (&eta;) to total Aerosol Optical Depth (AOD) and separate AOD growth due to fine-mode aerosol humidification and/or coagulation from AOD growth due to the increase in coarse particles or cloud contamination. Our results confirm the robustness of this graphical method. Large mineral dust is found to be the most important constituent in Northern Africa and Middle East. Under specific meteorological conditions, its transport to Southern Europe is observed from spring to autumn and decreasing with latitude. 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