Aspects of the surface circulation in the Liguro-Provençal basin and Gulf of Lion as observed by satellite-tracked drifters (2007-2009)

The surface circulation in the Liguro-Provençal basin and Gulf of Lion (north-western Mediterranean) is studied using satellite-tracked drifters in the period 2007-2009. Complex circulation patterns prevailed in the eastern Ligurian Sea, before the drifters joined the Northern Current (NC) in the coastal area off Genoa. Between 5°E and 7°30’E, most drifters (especially in summer) were advected offshore before heading to the east and eventually closing a basin-wide cyclonic circulation. This offshore turning is related to the wind and wind stress curl during north-westerly wind events. In constrast, most drifters proceeded into the Catalan Sea in the fall. Although the Western Corsican Current was well delineated by the drifters, no signature of the Eastern Corsican Current was shown, indicating limited connectivity between the Tyrrhenian and Ligurian seas in summer 2007. Pseudo-Eulerian velocity statistics were calculated in the coastal region extending between Genoa and the Gulf of Lion. Fast currents are evident on the shelf break, especially off Imperia (maximum of 90 cm/s) where the NC is closer to shore and narrower. A stagnation area inshore of the NC near Fréjus is characterized by little mean flow and low velocity fluctuations. Mean currents are also reduced off Menton-Nice where the variability is maximum. More to the west, the NC broadens and slightly reduces in strength