VARIABILITY AND DECADAL EVOLUTION OF TEMPERATURE AND SALINITY IN THE MEDITERRANEAN SEA SURFACE

Based on the Med-Atlas 20002 database data at Mediterranean Sea surface, analysis of spatial and temporal variations of temperature and salinity, as well as, the search of its possible trends are the main goals of this work. The used statistical techniques allowed us to obtain various climatological fields of temperature and salinity, on a period of 45 years (1955-1999). Spatial and temporal analysis of those fields shows that the north-south gradient is weaker than the east-west gradient. The strongest variability in both mean fields is sharper in downwelling areas than anywhere else, showing the colder and less saline surface waters. Warmer and saltiest water surface are located in southeast of the Levantine basin. The eastern Mediterranean Sea is generally more saline than the western basin. The temperature seasonal cycle is more marked than the salinity seasonal cycle. The summer-winter thermal and saline fields are completely contrasted, especially in the northern Adriatic Sea. The largest positive peak of inter-annual temperature variability is encountered in 1994, the largest negative peak in 1992. Whereas those related to salinity observed in 1983 and in 1997 respectively. The decadal variations indicate a cooling of Mediterranean Sea surface in 1970s and a northward warming since 1980s that accelerated in 1990s. The eastern Mediterranean Sea exhibits a higher warming rate as compared to the western basin, but the average increase is about 0.2 °C/decade. The Salinity rising corresponds to the cooling periods and the decreasing is associated with the warming ones.