BAROCLINIC WIND ADJUSTMENT PROCESSES IN THE MEDITERRANEAN-SEA

The wind-driven general circulation of the Mediterranean Sea is studie d using a primitive equation model. The model uses a 0.25-degrees hori zontal resolution and eight or 16 levels in the vertical. The model us es the Mediterranean basin geometry, and the Strait of Gibraltar is cl osed. The vertical density structure is initialized with annual averag e data, and the temperature and salinity values are fixed at the surfa ce to simulate perpetual annual mean conditions. The wind forcing cons ists of monthly mean climatological stresses. The results show that th e general circulation of the Mediterranean Sea has a multiple time-sca le character (seasonal excursions and steady state amplitudes are comp arable) and it is composed by sub-basin scale gyres corresponding to t he scale of the wind stress curl centers. The steady state circulation (annual mean average) is determined by a Sverdrup balance modified by viscous effects. The unsteady vertically integrated transport circula tion consists of sub-basin scale gyres similar to the steady state tra nsport components, which amplify seasonally and the partial or total r eversal of the currents in many subportions of the basin. The gyres ca n be stationary in position or propagating. This seasonal ocean respon se is partly constituted by Rossby modes due to the wind stress curl a nnual harmonic. The baroclinic circulation shows the seasonal shift of the North African Current from a position along the African coasts du ring winter to the center of the Balearic and Ionian basin during summ er.