Spatial and temporal variability of the sea surface temperature in the Gulf of Trieste between January 2000 and December 2006

The variability of the sea surface temperature (SST) of the Gulf of Trieste (northeastern Adriatic Sea) is studied using satellite observations spanning 2000–2006. After interpolation and validation of the SST data with in situ observations near Trieste, the satellite data are used to compute various statistical estimates (7-year, yearly and monthly means and empirical orthogonal functions modes). The main results obtained are: 1. The SST in the Gulf of Trieste is mostly variable at the seasonal scale, with temperature differences between summer and winter of 14 and 16C in the northern and southern areas, respectively. The larger seasonal variations in the northern section are related to the Isonzo and Tagliamento river runoffs and to its shallower bathymetry. In the mean, the meridional SST difference between north and south is only 2C. 2. Significant interannual variations are observed, with winter 2001 and summer 2003 showing the largest monthly anomalies (2–3C). Most of the seasonal and interannual variations are related to variability in the local heat flux with a time lag of about 2 months. No robust long-term cooling/warming trend is apparent in the observations. 3. The spatial structure of the SST in the Gulf is affected by the Isonzo and Tagliamento rivers (to the north), the warmer Adriatic water (to the south), the nonuniform warming in spring and wind induced mixing and cooling (to the east). The latter effect is mostly in the form of rapid temperature changes triggered by strong Bora events.