During the Meteor Expedition M31/2 in 1995 higher temperatures
were measured compared to those determined earlier in the Atlantis II Deep LCL brine (up to 71.6"C) and the Discovery lower brine section (nearly 50ยฐC) (Hartmann et al., 1997). This suggested an exceptionably strong increase in the temperature gradient during the previous two years, pointing to strongly enhanced hydrothermal/volcanic activity having taken place during this time. The CTD device used during this expedition had been adapted for the high temperatures and calibrated up to 60ยฐC (+O.O3C) by the ADM Company, Kiel-Warnau. Repeated lowerings of the device seemed to confirm the temperatures in the respective basins, and normal Red Sea deep water temperatures (near 21.6"C) were found in the expected range. Therefore we saw no reason to distrust these results.
During a new expedition with RV Sonne (SO12 1, 14 July to 6 August 1997) we had two disposable CTD devices from the ME-Company, Trappenkamp, both adapted and calibrated for temperatures up to 80ยฐC. The temperature readings received with these CTDs were identical to within 0.1 "C in the respective brine sections.
The profiles taken with these devices revealed that the temperatures are about 4 to 5ยฐC lower compared to the values measured two years before