Northern Adriatic Sea surface circulation and temperature/pigment fields in September and October 1997

Satellite images of surface chlorophyll-a concentration measured by the sea -viewing wide field-of-view sensor (SeaWiFS) and of sea surface temperature derived from advanced very high resolution radiometer (AVHRR) measurements , combined with in-situ drifter measurements of surface currents, and ancil lary wind, Po River discharge and surface salinity data, are used to descri be the surface dynamics in the northern Adriatic during the period Septembe r-October 1997. The satellite observations revealed very complex mesoscale dynamics, with t ime scales of a day or two and length scales of about 10 km, including the meandering and instability of basin-scale currents (e.g., the western coast al layer), jets/filaments and eddies. In addition, the two typical patterns of the Po River plume are observed and qualitatively explained in terms of wind forcing. A basin-wide double gyre pattern spreads the rich runoff wat er across most of the northern Adriatic from mid-September to early October , following Bora wind events and under stratified sea conditions. In contra st, in late October the Po plume is confined to the coast due to weaker win ds and de-stratified conditions. This variability in the Po River plume ext ension is also confirmed by in-situ salinity measurements. (C) 2001 Elsevie r Science B.V, All rights reserved.