Résumé
A specific processing chain applied to the infrared data of the Meteosat series satellites has been elaborated, The high repetitiveness of the observations allows to obtain 5 days synthesis SST maps over West Africa at a 6 km resolution. The resulting data set precisely describes the spatio-temporal dynamic of the coastal upwelling, from Mauritania to Guinea. (21 degrees N-9 degrees N), since 1984. The study area is dominated by the seasonal coastal upwelling which displays important interannual variations. The study of the superficial thermal field structure enables to link the mean position of the upwelled water to the topography of the continental shelf. Continuous monitoring of SST along the shelf allows the spatial estimation of an upwelling index and to characterize the seasonal dynamic of the upwelling via parameters such as the intensity and the duration of the seasonal transition phase and its seasonal lags. The example of an anomalous migration of Sardina pilchardus in Senegal leads to the hypothesis that neither the mean seasonal intensity nor the precocity of the upwelling is sufficient to initiate an abnormal southward migration and that the seasonal transition leads may be a key parameter in this (sic).