HYDRODYNAMICS AND GEOCHEMICAL FLUXES IN THE STRAIT OF OTRANTO

Results of Current Measurements

The North component of the low frequency hourly currents (tides and inertial oscillations filtered out) is given for the subsurface current record , since the longitudinal strait axes is dominantly in the N-S direction.

The presence of the flow reversals at station 301 with the periods of the order of ten days, coincides well with the N wind component, especially during May, June, November and December. Southerly winds facilitate the northward flow and viceversa. In November and December, the current fluctuations affected by the wind are superimposed on the strong outflow due to the increased precipitation, influencing the fresh water discharge along the western coast (as shown for the Po river). The fresh water discharge affects to a lesser extent the flow further offshore (station 3025) and is completely absent at station 304. Over the continental slope (st. 304) the flow is generally less energetic and directed prevalently southward.

Vector stick-diagrams for both mean daily wind and low-passed current, subsampled at 12:00 o'clock each day, recorded along the water column over the shelf (301) and slope (304) show that the current flow is the most energetic near the surface over the shelf and decreases both downwards and offshore. At station 301 at both depths currents are polarized dominantly in the NNE-SSW direction (topographyc constraint). At station 304 subsurface outflowing currents are interrupted with occasional flow reversals (the passage of the mesoscale eddies through the area). The intermediate flow is characterized with the frequent flow reversals, while the bottom current over the slope is dominantly outflowing.

Vedrana Kovacevic

e-mail : vedra@oce715d.ogs.trieste.it