Hydrography of the eastern part of the Aegean Sea during the Eastern Mediterranean Transient (EMT)

Abstract

Hydrographic features of the Aegean Sea were studied using CTDs collected in 4 cruises from 1991 to 1993. This period covers an interesting large-scale change in the thermohaline circulation in the Eastern Mediterranean and the Aegean Sea known as the Eastern Mediterranean Transient (EMT) and was first described during early 1990s. The cruise data is analyzed to depict the spatial variability of the water masses of the Aegean Sea in this period. We found Levantine Waters to be particularly prominent during the spring of 1992, more than in the other seasons. In the Central Aegean Sea the circulated cold water mixes with the upwelling water and very dense water remains behind in summer 1991. The Levantine Surface Water (LSW) is blocked and does not penetrate further to the north because of the existing upwelling water seen near Saros (Buyukkemikli Cape) and off-shore side of Baba Cape (product of northerly wind) especially in summer 1991 and in fall 1992. The water masses are nearly homogeneous vertically with the influence of strong wind and convective mixing in winter time. In this study, we underline the contribution of the eastern part of the Aegean to the rising isopycnal levels during the EMT. In turn, i) the dense water cascades from eastern shelf of the Aegean Sea, ii) the upwelling and downwelling processes in the northern and central basins, iii) the cooling effect of Black Sea Water (BSW) on upwelled water at the south of the Lemnos Island (open sea convection) and iv) local wind forcing.