The winter circulation of the Adriatic Sea

Abstract

The winter circulation of the northern Adriatic Sea is examined in the light of 1965–1966 Bannock data. A vertically integrated numerical model of the flow is used to study the relative importance of evaporation, wind stress, coastal river runoff, and exchange with the Southern Adriatic Sea for the wintertime fields of vertically integrated mass transport and density. A strong and sudden outbreak of cold, dry central Asian air over the Adriatic Sea during January, 1966, resulted in such rapid evaporation rates that water columns evidently overturned continuously. Changes in the density and temperature in the interior of the basin were dominated by surface heat fluxes. Initially sea temperatures were high and evaporation was rapid but as it continued, sea temperatures fell and the rate of evaporation decreased. Model calculations suggest that the strong horizontal density gradient set up by evaporation and coastal inflow of fresh water is an important source of the large scale wintertime circulation. This circulation, counterclockwise in the northern Adriatic Sea with a net transport of about 0·4 × 10 6m 3 s −1, is closed upon itself in most of the model solutions because of the relief of the ocean bottom. Mass exchange with the Southern Adriatic Sea appears to be of secondary importance for this circulation.