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Intense Convection over West Africa During AMMA SOP3 Experiment

ERA-Interim product from the European Center for Medium-Range Weather Forecast (ECMWF) assimilation of African Monsoon Multidisciplinary Analysis (AMMA) resources, Meteosat satellite images, and synoptic observa- tions were used to study local- and regional-scale environments associated with intense convective systems dur- ing the AMMA-SOP3 experiment over West Africa in the Northern Hemisphere of summer 2006. The convective system, from the 21st to 23rd of August 2006, was more active at 0000 and 1800 UTC showing diurnal cycle of deep convection over West Africa where the African easterly waves (AEWs) are developed downstream. Down- stream barotropic and baroclinic energy conversions associated with strong AEWs are important for the mainte- nance of AEW activity in West Africa. Barotropic energy conversions dominate south of the African easterly jet (AEJ), while baroclinic energy conversions are most important north of the AEJ. From a dynamical viewpoint, the low-level vorticity presents strong positive values over the sea and Sahara zone, indicating that exists on the cyclonic shear side of the African easterly jet, which is consistent with baroclinic growth. The 925-hPa equiv- alent potential temperature structure show a maximum over the Sahara which corresponds to the depression ob- served in this region. A mosaic of three hourly infrared (IR) satellite images, depicts a very distinct signal from an initial region of convection, developing through several stages and moving off the African coast. These observa- tions, along with those available from the World Weather Watch, provide an opportunity to carry out numerical weather prediction (NWP) studies over West Africa utilizing high resolution limited area models.

Auteur(s) : André lenouo, Saidou Moustapha Sall, Daouda Badiane, Amadou Thierno Gaye, F. Kamga Mkankam
Année de publication : 2016
Revue : Atmospheric Research
Type : Article
Mise en ligne par : SALL Saïdou Moustapha