SEA-SURFACE TEMPERATURE RETRIEVAL IN TROPICAL AREA WITH METEOSAT - THE CASE OF THE SENEGALESE COASTAL UPWELLING

Many methods which are commonly used for sea surface temperature (SST) retrieval are frequently based on theoretical studies which may limit the needs of a real-time monitoring of hydro-climatic changes in the ocean. The method for SST retrieval described here, calls for a multi-temporal processing of data from the Meteosat series geostationary satellite coupled with the sea-truth measurements provided by ships of opportunity. In the Atlantic inter-tropical region, and especially in coastal areas, the method helps to obtain a very satisfactory monitoring on the important seasonal changes, with an easier and higher spatio-temporal resolution than other available methods. In this case the process of enrichment of coastal zones needs a detailed spatio-temporal description, leading to the choice of a more suitable time scale for studies of small spatial scale biological changes. An original preliminary SST climatology has been produced from Meteosat satellite data covering the 1984-1989 period of the upwelling season along the Mauritanian and Senegalese coasts. Its precision in coastal upwelling areas largely overcomes existing climatology and allows a precise calculation of SST anomalies. The real-time production of daily SST maps provides assistance for a local tuna fishery and has been used for this purpose in the tropical Atlantic Ocean at Meteo-France (Lannion, France) and at the University of Abidjan (Ivory Coast).