Seasonal differences in intraseasonal and interannual variability of Mediterranean Sea surface temperature

Abstract

AbstractSea surface temperature (SST) data from the NOAA OI SST data set for 1982–2011 are used to investigate intraseasonal and interannual variability of Mediterranean SST during winter and summer seasons. It is shown that during winter the intraseasonal SST fluctuations are larger than the interannual SST variations in the western Mediterranean (e.g., the Tyrrhenian Sea), but smaller in the central and eastern Mediterranean Sea. In summer, the intraseasonal SST fluctuations are larger in almost the entire Mediterranean basin. Also summertime intraseasonal SST fluctuations are larger (up to three times near the Gulf of Lions) than their wintertime counterparts in the entire Mediterranean basin. The interannual SST variations are larger during summer in the western and central Mediterranean Sea and during winter in its eastern part. The leading empirical orthogonal functions (EOFs) of the Mediterranean SST and of the intensities of its intraseasonal fluctuations are characterized by the differing spatial‐temporal structures both during winter and summer implying that their interannual variability is driven by different physical mechanisms. During winter, the EOF‐1 of SST is associated with the East Atlantic teleconnection, whereas EOF‐1 of the intensity of intraseasonal fluctuations is not linked significantly to regional atmospheric dynamics. The second EOFs of these variables are associated, respectively, with the East Atlantic/West Russia and the North Atlantic teleconnections. While during summer the atmospheric influence on Mediterranean SST is generally weaker, it is revealed that the EOF‐1 of the intensity of intraseasonal SST fluctuations is linked to the Polar teleconnection.