Atmospheric Chemistry and Physics Discussions www.atmos-chem-phys-discuss.net 1680-7367 1680-7375 9 4 2009 10.5194/acpd-9-16295-2009 http://www.atmos-chem-phys-discuss.net/9/16295/2009/ http://www.atmos-chem-phys-discuss.net/9/16295/2009/acpd-9-16295-2009.html http://www.atmos-chem-phys-discuss.net/9/16295/2009/acpd-9-16295-2009.pdf 16295 16330 2009-07-30 Aerosol vertical distribution and optical properties over M'Bour (16.96° W; 14.39° N), Senegal from 2006 to 2008 J.-F. Léon jean-francois.leon@aero.obs-mip.fr Y. Derimian I. Chiapello D. Tanré T. Podvin B. Chatenet A. Diallo C. Deroo Laboratoire d'Optique Atmosphérique, CNRS-Université de Lille 1, Villeneuve d'Ascq, France Laboratoire Inter-Universitaire des systèmes Atmosphériques, CNRS-Université de Paris 7–12, Créteil, France Institut de Recherche pour le Développement, Dakar, Senegal now at: Laboratoire d'Aérologie, CNRS-Université Paul Sabatier, Toulouse, France We present ground-based measurements of aerosol mass, optical properties and vertical extinction profiles acquired in M'Bour, Senegal (16.96° W; 14.39° N) from January 2006 to September 2008. This place of the word is all year long affected by the export of mineral dust as it moves westward to the north Atlantic ocean. The maximum in the dust activity is observed in summer (June–July), corresponding to a maximum in the aerosol optical thickness (above 0.5) and single scattering albedo (above 0.95). It also corresponds to a maximum in the top altitude of the transported aerosol layer (up to 6 km) and aerosol optical thickness scale height (up to 3.5 km) due to the presence of the Saharan Air Layer located between 2 and 6 km. The late summer shows an additional low level aerosol layer that increases in thickness in autumn. Severe dust storms are also systematically observed in spring (March) but with a lower vertical development and a stronger impact (factor 2 to 3) on the ground-level mass compared to summer. Sporadic events of biomass burning aerosols are observed in winter (January) and particularly in January 2006 when the biomass burning aerosol are advected between 1.5 and 3.5 km high. On average, the seasonal signal in the aerosol optical properties and vertical distribution is very similar from year to year over our 3 year monitoring. 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