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Journal Article: ID no. (ISBN etc.):  0148-0227 BibTeX citation key:  McConnell2008
McConnell, C. L., Highwood, E. J., Coe, H., Formenti, P., Anderson, B. E., Osborne, S., Nava, S., Desboeufs, K., Chen, G. & Harrison, M. A. J. (2008) Seasonal variations of the physical and optical characteristics of Saharan dust: Results from the Dust Outflow and Deposition to the Ocean (DODO) experiment. IN Journal of Geophysical Research - Atmospheres, 113. D14S05.
Added by: Devic 2009-09-22 15:12:08    Last Edited by: Fanny Lefebvre 2011-01-21 11:35:21
Categories: General
Keywords: Aerosol, Climate
Creators: Anderson, Chen, Coe, Desboeufs, Formenti, Harrison, Highwood, McConnell, Nava, Osborne
Collection: Journal of Geophysical Research - Atmospheres
Bibliographies: Prior150410

Peer reviewed
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Maturity index:  published

North African dust is important for climate through its direct radiative effect on solar and terrestrial radiation and its role in the biogeochemical system. The Dust Outflow and Deposition to the Ocean project (DODO) aimed to characterize the physical and optical properties of airborne North African dust in two seasons and to use these observations to constrain model simulations, with the ultimate aim of being able to quantify the deposition of iron to the North Atlantic Ocean. The in situ properties of dust from airborne campaigns measured during February and August 2006, based at Dakar, Senegal, are presented here. Average values of the single scattering albedo (0.99, 0.98), mass specific extinction (0.85 m2 gāˆ’1, 1.14 m2 gāˆ’1), asymmetry parameter (0.68, 0.68), and refractive index (1.53ā€“0.0005i, 1.53ā€“0.0014i) for the accumulation mode were found to differ by varying degrees between the dry and wet season, respectively. It is hypothesized that these differences are due to different source regions and transport processes which also differ between the DODO campaigns. Elemental ratios of Ca/Al were found to differ between the dry and wet season (1.1 and 0.5, respectively). Differences in vertical profiles are found between seasons and between land and ocean locations and reflect the different dynamics of the seasons. Using measurements of the coarse mode size distribution and illustrative Mie calculations, the optical properties are found to be very sensitive to the presence and amount of coarse mode of mineral dust, and the importance of accurate measurements of the coarse mode of dust is highlighted.
Last Edited by: Fanny Lefebvre