Large-scale spreading of deep waters in the Western Mediterranean Sea by submesoscale coherent eddies

Two large-scale free-drifting isobaric-floats experiments, SOFARGOS/Marine Science and Technology Programme, phase 2 (MAST2) and Mass Transfer and Ecosystem Response (MATER)/MAST3, undertaken in 1994-95 in the northwestern Mediterranean Sea and in 1997-98 in the Algerian Basin, respectively, have revealed for the first time that Western Mediterranean Deep Water, newly formed by deep convection in the Gulf of Lion (the so-called Medoc site), can be advected several hundreds of kilometers away from the formation area by anticyclonic submesoscale coherent vortices (SCVs). This behavior implies that SCVs participate actively in the large-scale thermohaline circulation and deep ventilation of the western Mediterranean Sea. These SCVs are characterized by small radius (∼5 km), very low potential vorticity, high aspect ratio (∼0.1), and extended lifetime (>0.5 yr).