engleski

Peculiar Behaviour of the Mediterranean Sea Level over the Last Fifty or So Years

An analysis of tide-gauge data shows that there are two processes influencing the Mediterranean sea level variability at the longest time scales, and that both had in recent times some unusual characteristics. One of the processes is sea level rise, its most important feature being a slowing down that was recorded since 1960s and that now appears to be over. The deceleration was most obvious in the Adriatic Sea and the West Mediterranean while it was not observed in the Black Sea. The other process is decadalscale variability, undergoing amplification throughout the Mediterranean. The signal is clearly bidecadal in the Adriatic and Aegean Seas, and is characterized by somewhat smaller periods (5 – 7 years) in the West Mediterranean and the Black Sea. The two processes could be related to two-faceted atmospheric variability over the Mediterranean – a general increase of the air pressure lasting since 1950s and a decadal-scale atmospheric variability manifested in anomalously high air pressures around the years 1958, 1974 and 1992 and anomalously low air pressures around the years 1969, 1987 and 2004. The atmospheric dynamics supported changes of the wind regime, surface buoyancy forcing and river inputs that, together with the air pressure, influenced the Mediterranean sea level. Besides the natural phenomena, anthropogenic factors could also have played a role. In particular, man-induced reduction of the inflow of some major rivers feeding the East Mediterranean is suspected of lowering the sea surface and of influencing the thermohaline properties and circulation in the basin.

sea level; trend; decadal variability

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