ADCP observations of the western Adriatic slope current during winter of 2001

Data from an Acoustic Doppler Current Profiler (ADCP) mooring maintained during the winter of 2001 in 57 m of water near Senigallia, Italy are used to describe the winter conditions of the Western Adriatic Current in the northern Adriatic Sea. Wind and water temperature measurements from the Acqua Alta tower in 19 m water depth off Venice and winds from a 4-km resolution reanalysis model, COAMPS™, are used to interpret the ADCP data, especially with respect to currents generated by bora winds. At the ADCP site, mean depth-average current for the winter deployment period was 10.4 cm/s toward 140°, roughly aligned with local bathymetric contours. Both mean currents and fluctuations about the means were highly barotropic during the winter. Southeastward (along-shore), mean currents increased slightly (1.8 cm/s) with depth between 7 and 47 m following a nearly linear trend. Offshore (cross-slope), mean currents only increased (2.0 cm/s) deep in the water column, between 35 and 51 m. Current variability was dominated by four bursts of currents in which flow toward the southeast greatly increased. These bursts followed bora winds, the timing of which was identified by measured winds at the Acqua Alta tower. Depth-averaged, de-tided currents exceeded 30 cm/s during all four events, and reached 45 cm/s during one event. Correlations between these along-shore currents and simulated wind stress from the COAMPS model were calculated over the whole north Adriatic. The cross-covariance between currents and wind stress had a spatial pattern similar to the bora wind itself, reaching maxima along the northern Adriatic coast, off the southern tip of Istria, and near Ilovik Island (14.5°N, 44.4°E). Wind stress in these regions had stronger correlation with currents at the mooring than did wind stress anywhere near the mooring. Bottom water at the mooring was too warm for it to have been North Adriatic Dense Water, except perhaps for a brief pulse of cold water associated with the third current burst on April 1st.