Scales and variability of the sea surface temperature distribution in the Adriatic Sea

Scales and variability of the Adriatic sea surface temperature (SST) distribution in the period January 1991 to December 2000 are studied by means of 8-day composite, 4-km resolution, SST data. Scales of the SST are defined as scales of the SST autocorrelation function. Assuming an exponential correlation model, scales of the SST are quantified as e-folding times and distances of the SST autocorrelation function. Variability in the SST is analyzed through empirical orthogonal function (EOF) analysis. From summer to winter, spatial scales of the SST in the along-basin direction remain unchanged while in the across-basin direction they decrease, resulting in scales that are slightly shorter (10-15%) in winter than in summer. The spatial distribution of temporal scales displays two patterns: the first, characterized by low values, is located in the northern part of the basin and along the Italian coast, and the second, characterized by high values, covers the rest of the basin. The SST variability is dominated by the annual signal, which explains 45% of the overall variance. The main structures of the Adriatic circulation leave their signature on the first three EOFs, whose spatial variability occurs on wavelengths longer than 200 km in the along-basin direction and, in the across-basin direction, in the band 25-50 km and at 80 and 100 km. EOF coefficients are characterized by oscillating components with periods of 20 days to 6 months.