Observation and modeling of the winter coastal oceanic circulation in the Gulf of Lion under wind conditions influenced by the continental orography (FETCH experiment)

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Abstract
Hydrological and currentmeter observations were collected on the continental shelf and slope of the Gulf of Lion during the FETCH experiment (13 March to 15 April 1998). Results from the first part of the cruise, characterized by strong northern winds, are presented. The hydrological structures evidence well‐mixed water masses on the eastern and western ends of the shelf. In the central part, the situation is more complex, with the influence of the Rhône river's freshwater plume in the first 40 m of the water column and, closer from the bottom, with the confrontation of downwelled coastal cold water and upwelled warmer and saltier slope water. Current measurements show the path of the cyclonic circulation along the slope, which is part of the general circulation of the western Mediterranean, and suggest the presence of large and temporary eddies on the shelf. This oceanic circulation is simulated with a free surface three‐dimensional model using realistic forcing. The model outputs are in agreement with the main hydrological and circulation patterns. The results further indicate that coastal eddies are generated by the mesoscale structure of the wind field.