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Communication incl. Poster: BibTeX citation key:  Thorncrofta
Thorncroft, C. D., Nguyen, H., Zhang, C. & Peyrillé, P. 2009. Annual cycle of water vapour transport in the West African monsoon region. Work presented at Third International AMMA Conference, July 20—24, at Ouagadougou, Burkina Faso.
Added by: Devic 2009-10-05 21:25:02    Last Edited by: roussot 2009-10-16 16:38:17
Categories: General, Monsoon system and its variability
Keywords: Atmospheric Boundary Layer
Creators: Nguyen, Peyrillé, Thorncroft, Zhang
Publisher: African Monsoon Multidisciplinary Analyses (Ouagadougou, Burkina Faso)
Collection: Third International AMMA Conference

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The West African monsoon (WAM) has a distinctive and irregular annual cycle in rainfall that remains a challenge to understand and predict. The location of peak rainfall, which remains in the northern hemisphere throughout the year, moves from the ocean to the land in boreal Spring. Around the end of June there is a rapid shift in the location of peak rainfall between the coast and around 10°N where it remains until about the end of August. In September the peak rainfall returns equatorward relatively steadily and is located over the ocean again by October. The fact that the peak rainfall migrates irregularly compared to the peak solar heating is due to the interactions that occur between the land, atmosphere and ocean. These interactions take place through the regional circulations connecting the land and the ocean. The purpose of this work is to explore how the climatological annual cycle of these circulations are related to surface conditions and how they impact the regional transport of water vapour and its convergence.
This presentation will highlight the nature of the water vapour transports and their relationship with surface conditions in the following key phases of the annual cycle described in terms of the location of peak rainfall: (i) Ocean phase (October-April), (ii) Coastal rainfall onset (May), (iii) Coastal rainfall reduction (June) and (iv) Sahelian rainfall onset (June-July). Special emphasis is given to the relative roles of the Atlantic cold tongue and Saharan Heat low during the annual cycle.
Last Edited by: roussot