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Adama Bamba : IInfluence des conditions de surface continentales dans la variabilité de la pluie en Afrique de l’Ouest : rôle de l’humidité du sol

par HYBIS - 10 septembre 2014

Titre : IInfluence des conditions de surface continentales dans la variabilité de la pluie en Afrique de l’Ouest : rôle de l’humidité du sol

sous la direction de T. Pellarin, O. Adefolalu et A. Konare. Federal University of technology, Akure (Nigéria)

Financement WASCAL (Programme international de formation et de recherche financé par le gouvernement Allemand sur l’Afrique), démarrage janvier 2012

Absrtact

It has been observed that during the last decades West Africa region is receding back to the wet condition. Nevertheless land surface degradation is still going on in some areas. However, rainfall is strongly dependent on the Mesoscale Convective Systems (MCSs) (80%) whose life cycle is affected by land surface condition. It also interacts with atmospheric features at synoptic scale but the mechanisms of these processes are still not well known. Meanwhile, the spatiotemporal variability of rainfall over West Africa is coming less predictable so the pertinent questions are : what mechanisms are involved in the relationship between rainfall variability within the West Africa region on both land surface condition (soil moisture and albedo) and atmospheric features at synoptic scale African Easterly Waves (AEWs), African Easterly Jet (AEJ) ? Using these regional and synoptic events, how predictable will be the rainfall ? The objective of this thesis is to characterize factors of synoptic environment and the land surface condition influencing the rainfall at regional scale. The influence of the regional climate variability and the local land surface change on the spatiotemporal variability and the onset of the rainy season will be analyzed. The parameters which will be used for the study are : the surface condition through soil moisture and albedo measured by SMOS satellite and NDVI within West Africa, and, atmospheric features at synoptic scale. We will be focusing on the sensitivity study over West Africa and the relationship between these parameters. As a methodological approach, the dynamical downscaling using RegCM4 and statistical modeling to validate the hypothesis will be done. The appropriate data are satellite images for NDVI, soil moisture and albedo from SMOS satellite, SST and WAM data from AMMA campaign. Some of the data which will be used are already available (AMMA) ; others will be downloaded from the internet and the station observation data will be used. For the validation, the observation data from meteorological station will be used.