Interdecadal Changes in Mediterranean Evaporation Variability and its Links to Regional Teleconnections

Monthly evaporation data for 1958-2010 from the Woods Hole Oceanographic Institution dataset are used to investigate interdecadal changes in interannual variability of Mediterranean evaporation and its links to regional climate. Analysis performed for the two climate sub-periods characterized by the downward (1958-1978) and upward (1979-2010) trends of evaporation revealed significant season-dependent interdecadal changes in its interannual variability. The largest changes in interannual variability have been revealed during fall when the leading EOFs are characterized by a zonal dipole pattern (except in November 1979-2010). During winter and spring the EOF-1 and EOF-2 are characterized, respectively, by a monopole pattern and a zonal dipole and are associated with the East Atlantic (EA) and the East Atlantic – West Russia (EAWR) teleconnections. It is shown that interdecadal changes in interannual variability of Mediterranean evaporation during cold season were determined by the EA transition from the strongly negative to more neutral phase that occurred in late 70s. Seasonally-dependent changes in the structure of the leading evaporation EOFs reflect changing roles of the EA and EAWR which impact near surface air temperature, specific humidity and wind. Large interdecadal changes are also revealed in the links between Mediterranean evaporation and regional precipitation. These changes are generally consistent with the detected changes in the links to atmospheric dynamics. The leading (monopole) EOF pattern of evaporation mostly influences precipitation over eastern/southeastern Europe and European Russia whereas the EOF-2 (being associated with local atmospheric dynamics) mainly impacts precipitation over western Europe and some other regions around the Mediterranean basin.