Klaver A. auteur aut IRD Formenti P. auteur aut IRD Caquineau Sandrine auteur aut IRD Chevaillier S. auteur aut IRD Ausset P. auteur aut IRD Calzolai G. auteur aut IRD Osborne S. auteur aut IRD Johnson B. auteur aut IRD Harrisone M. auteur aut IRD Dubovik O. auteur aut IRD text journalArticle eng text/pdf born digital access This paper presents new results on the composition, size and shape of mineral dust particles from African sources which were obtained by analysis of bulk filter samples collected in June 2007 onboard the BAe-146 research aircraft of the Facility for Airborne Atmospheric Measurements (FAAM). The aircraft was operated over Mauritania, Mali and Niger during the Geostationary Earth Radiation Budget Intercomparisons of Longwave and Shortwave radiation (GERBILS) campaign. Dust sampled during the campaign originated from various sources, including locally in the Sahel as a result of large-scale convective activity. Regardless of origin, clays (illite, kaolinite) dominated the total volume (79-90%); the remainder was composed of quartz, calcium-rich minerals (calcite, dolomite, gypsum) and alkali feldspars. Iron oxides, measured using a selective chemical extraction method, accounted for 1-3% of the total dust mass. The dependence of particle number size and shape distribution on the origin of dust seems minor too, although our results might be slightly misleading due to the fact that those kinds of data have been gathered on flights when dust had comparable origins and residence time. Mineral dust is only weakly absorbing in the mid-visible wavelengths (single scattering albedo omega(0) > 0.95 at 550 nm), and omega(0) measured values can be reproduced by measuring the bulk fractions of the major minerals, i.e. clays, quartz, calcite and iron oxides. At this wavelength, knowledge of the nature of clays and iron oxides, or the state of mixing of the minerals, does not induce significant differences in the results. A more precise description of the nature of clays and iron oxides is necessary at lower wavelengths owing to larger differences in their spectral optical properties. In particular, knowledge of the nature of the dominant clay is important for determining light scattering in the backward hemisphere. specialized desert aerosols West Africa mineralogical composition single scattering albedo sensitivity calculations 021 020 137 658 1193-1210 2011 0035-9009 https://www.documentation.ird.fr/hor/fdi:010053768 10.1002/qj.889 0035-9009 [F B010053768] https://www.documentation.ird.fr/hor/fdi:010053768 https://www.documentation.ird.fr/intranet/publi/2011/09/010053768.pdf Accès réservé (Intranet de l'IRD) IRD - Base Horizon / Pleins textes 2011-10-06 2017-08-23 fdi:010053768 fre