Seasonal and Inter-Annual Variations of the Sea Surface Circulation in the Central Mediterranean Sea Derived from 11 Years of Topex/Poseidon and ERS-1/2 Data

Seasonal and inter-annual variations of the surface circulation in the central Mediterranean Sea are examined. Sea level anomaly variations are obtained using 11 years of merged data from two altimeters (TOPEX/Poseidon and ERS-1/2). It is first shown that the surface circulation pattern is characterized by an intense eddy activity. This is supported by high values of eddy kinetic energy, particularly in the Strait of Sicily and in the eastern part of the basin. Moreover, the month-to-month changes of the basin-integrated sea level show a strong seasonal cycle with amplitude of nearly 16 cm month 1. We also observed a substantial inter-annual variation with amplitude of nearly 5 cm year 1. The surface geostrophic current anomalies deduced from the satellite sea level anomaly as well as the total current confirmed the observed high spatial variability of the sea surface circulation and particularly reproduced with some realism the meanders of the Libyan coastal current. Present results confirm the capability of the satellite altimeter data to reproduce the main features of the surface circulation and its ability to measure accurately the variable part of the sea surface topography.