Winter intermediate water lenses in the Ligurian Sea

Hydrographic measurements carried out in the Ligurian Sea in early spring 1991 revealed the existence of mesoscale lenses at intermediate depths that were remarkably different from the environmental waters. The lens temperature was up to 0.7°C colder, salinity 0.2 lower and the oxygen content 0.8 ml/l higher than the waters outside. The most significant of these lenses was found along the Ligurian coast between the surface layer of Modified Atlantic Water (MAW) and the Levantine Intermediate Water (LIW) below it. This lens was clearly the result of the sinking of water of the central region of the basin along the isopycnal slope associated with the large scale cyclonic circulation. The precise identification of its characteristics allowed us to obtain some basic information on the processes responsible for lens formation and evolution. This can bring new elements for the study of dense water formation and spreading in the Northwestern Mediterranean.