Response of the Mediterranean Sea thermohaline circulation to observed changes in the winter wind stress field in the period 1980-1993

This paper seeks to model changes in deep water production in the eastern M editerranean induced by changes in winter wind stress. An analysis of indiv idual monthly wind stress fields over the Mediterranean for 1980-1993 from the SOC flux data set shows that an intensification of the winter mean (mai nly January) wind stress over the Aegean Sea and Levantine basin occurred i n the latter half of this period. A weakening of the Mistral occurred at th e same time. Two monthly wind stress climatologies were created using the 1 980-1987 and 1988-1993 periods, and these were used to force an ocean gener al circulation model of the Mediterranean, with climatological surface T, S relaxation. The Levantine intermediate water (LIW) dispersal path in the I onian is altered in the 1988-1993 experiment with no pathway to the Adriati c and, consequently, greatly reduced exchange at Otranto and a collapse in Adriatic deep water formation. In contrast, there is an increased exchange of LIW at the Cretan are straits and enhanced Aegean deep water production in the 1988-1993 experiment. Much more Aegean water exits into the Levantin e and Ionian basins as is shown by an east-west cross section south of Cret e, along a similar path to the Meteor cruise in 1995. Changes in air-sea fl uxes are diagnosed from the model showing a small increase in wintertime co oling over the Aegean and reduced cooling over the Adriatic after 1987. Whi le the changes in air-sea fluxes are probably underrepresented by this simu lation, the large changes induced by the wind forcing suggest this could be a mechanism in the altered thermohaline state of the eastern Mediterranean since 1987.