Atmospheric Chemistry and Physics Aerosol characterization in Northern Africa, Northeastern Atlantic, Mediterranean Basin and Middle East from direct-sun AERONET

Abstract. We provide an atmospheric aerosol characteriza-tion 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 cy-cle within the 1994–2007 period. We extensively test and ap-ply 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 re-lies on the combined analysis of the Ångström exponent (α) and its spectral curvature δα. Plotting data in these coordi-nates allows to infer aerosol fine mode radius (Rf) and frac-tional contribution (η) to total Aerosol Optical Depth (AOD) and separate AOD growth due to fine-mode aerosol humidi-fication and/or coagulation from AOD growth due to the in