African Dust Observed over Canary Islands ß Source-Regions Identification and Transport Pattem for some Summer Situations

Bergametti, Gilles ; Gomes, Laurent ; Coude-Gaussen, Genevieve ; Rognon, Pierre ; Lecoustumer, M.N.

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Bulk filtration samples of dust were collected on Fuerteventura (Canary Islands) in July 1985 in order to investigate African dust transport over this region during stmuner. Air mass trajectories and elemental and mineralogical analyses allowed us to distinguish between oceanic and continental influences: three African dust transport cases occured during this period. Geochemical and mineralogical tracers, combined with air mass trajectories, indicate that two different source regions of dust (Sahelian and Moroccan ones) are involved. Each of these exhibits specific Si/A1 and Fe/AI ratios that can be considered as tracers of dust origin. A meteorological study, based on satellite imagery, meteorological maps, and air mass trajectories, confirms the previous identification of the source region. It is also possible to describe the meteorological situation controlling the atmospheric pathway of the dusts from the source regions up to the Canary Islands. This study suggests that some source regions (especially the Sahelian one) of dust affecting the Canary Islands during summer are rather different from the Moroccan ones observed in a spring situation by Coucl?-Gaussen et al. (1987).</p>

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