SATELLITE INVESTIGATIONS OF A CYCLONIC GYRE IN THE CENTRAL TYRRHENIAN SEA (WESTERN MEDITERRANEAN-SEA)

Thermal satellite images related to surface temperature of the Tyrrhenian Sea(western Mediterranean Sea) show an elliptic cold patch, suggesting the presence of a wind-induced cyclonic gyre with well-defined meanders of comparatively constant wavelength. In order to gain insight into the dynamics of the gyre these data are compared with results of two classical linear models, that of Crepon and Richez on wind-induced upwellings and that of Gill on currents due to a buoyancy discontinuity in rotating channels. The large-scale gyre meanders are analyzed using theoretical information on baroclinic instability models. It results that the gyre is due to winds blowing eastward from the Mouths of Bonifacio and to the buoyancy due to a thermal front along 41 degrees E. With this general procedure, from satellite images an estimate of the deep hydrologic quantities is obtained; this technique is of interest also for other similar systems.