Multidecadal Variability in Mediterranean Sea Surface Temperature and Its Sources

The multidecadal variability in Mediterranean Sea surface temperature (MSMV) exerts important climate impacts on both the Mediterranean region and remote areas at hemispheric scales and has long been identified in previous studies. However, its key region and source are still unclear. For the first time, we show that the key region of the MSMV is in the eastern Mediterranean, where the MSMV can persist throughout the year. The MSMV in the central and western Mediterranean occurs mainly in summer. Comparison of the North Atlantic Oscillation (NAO) and Atlantic Multidecadal Variability (AMV) indices shows that the cumulative NAO index has a better consistency with the MSMV, suggesting that the MSMV most likely results from the cumulative effect of NAO atmospheric forcing on ocean circulation in the Mediterranean Sea. The stable lag relationship between the cumulative NAO index and the MSMV provides a natural indicator for the decadal prediction of the MSMV.