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Communication incl. Poster: BibTeX citation key:  Arnaulta
Arnault, J. & Roux, F. 2009. Tropical cyclogenesis off the West African coast: a synoptic point of view. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: Devic 2009-10-12 10:52:50    Last Edited by: roussot 2009-10-16 16:27:58
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Categories: Atmospheric processes
Creators: Arnault, Roux
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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Abstract
Following previous authors’ ideas, it is hypothesized that tropical cyclones develop near Cape Verde Islands only when an intense African easterly wave (AEW) trough encounters a low level large-scale cyclonic circulation off-shore, as the southwesterly monsoon flow and the northeasterly maritime trade winds get connected. The low level northern vortex of the AEW certainly favours this connection. It is also hypothesized that another necessary ingredient, for such an AEW trough with enhanced low level circulation to evolve into a tropical cyclone, is the formation of deep convection near the center of cyclonic vorticity. However, in the presence of mid-level anticyclonic Saharan air or/and a mid-latitude trough north of Cape Verde Islands, the cyclogenetic evolution of the AEW trough generally fails off the West African coast, even in the presence of favourable low level cyclonic condition. This concept of Cape Verde tropical cyclone formation is investigated using five seasons (2004 to 2008) of ECMWF (European Centre for Medium-range Weather Forecast) analyses and Meteosat-9 images in the water vapour channel.
Last Edited by: roussot