CHLOROFLUOROMETHANE AND OXYGEN IN THE EASTERN MEDITERRANEAN

CFM-12 (chlorofluoromethane, CCl2F2) data from the 1987 expedition of the F.S. Meteor in the Eastern Mediterranean are presented and discussed in the context of simultaneous oxygen and hydrographic measurements. Taken together, these data strongly suggest that the Adriatic is the only substantial source of bottom and deep water for the Eastern Mediterranean, in that no signatures of Aegean-derived water are found in the Levantine and Ionian Basins below about 1200 m depth. On the basis of a CFM-12 budget, the time-averaged inflow rate of Adriatic deep water into the Ionian is estimated to be 0.3 +/- 0.1 Sv. The lowest CFM-12 and oxygen concentrations are found in the deep water between 2800 and 1200 m depth. This water mass is considered the oldest water in the Eastern Mediterranean and appears to be renewed by upwelling of bottom water. A lens of high CFM-12 water centered near 700 m depth is observed at a single station (Sta. 756) south of Crete. According to multi-parameter water analysis this water originates in the Aegean (about 300 m depth). The form of the theta-S relation and the fact that the anomalous water was only observed at one station suggest that inflow of Aegean water occurs in the form of isolated lenses. The salinity distribution in 700 m depth. together with the anomaly at Sta. 756, indicates that water from the Aegean spreads out in the western Levantine and the Ionian between about 500 and 1200 m depth. We propose to denote this water mass Cretan Intermediate Water. Atlantic Water has CFM-12 concentrations in equilibrium with 1987 atmospheric concentrations everywhere in the Eastern Mediterranean, and oversaturations for both CFM-12 and oxygen are found in the seasonal thermocline above it. In contrast, Levantine Intermediate Water (LIW) is undersaturated for both oxygen and CFM-12, even in the presumed formation areas in the northeast Levantine.