Satellite observations of cold filaments and surface jets in the Mediterranean Sea

摘要

Thermal satellite images relative to the years 1997-2000 are analyzed in this study, in order to infer cold filament and surface jet dynamics in the Mediterranean Sea. The main zones in which these phenomena are seen to occur, are characterised by upwelling and/or the funnelling of strong cold winds by a somewhat irregular coastal orography. Indeed, intense air-sea interaction in the coastal zone is known to generate a particularly strong input of potential vorticity into the sea, and this in turn gives origin to upwellings, cold filaments and jets. In the Mediterranean Sea the geographical zones with a higher frequency in these jets are the two lobes of the southern Sicilian coast, the sea off Olbia in Eastern Sardinia, that south of the island of Crete where a particularly intense large scale turbulence field is evident, and the Balkanic coast of the Adriatic Sea. In addition the theoretical analysis of these jets' evolution using a modern version of the potential vorticity conservation, valid even if friction and entrainment are considered, gives further insight into these systems' dynamics.