Thermal frontal zones in the eastern Mediterranean Sea

From August 7 to October 4, 1966, near-surface temperature measurements in the eastern Mediterranean Sea were taken on cruise 61 of the R.V. Chain. These measurements consisted of towing a constant-level, continuously recording temperature sensor behind the ship and were supplemented by bathythermograph lowerings taken every 2 hours. Visual inspection of these data shows that near-surface horizontal temperature changes along the cruise track were not continuous, but rather occurred in an approximate stepwise fashion at 20 locations, where the temperature gradient exceeded 1°C/10 km either at the surface or in the seasonal thermocline. The geographical distribution of the locations of these gradients suggests that the ship made 19 crossings of two long thermal frontal zones. One frontal zone was located in the Ionian basin and the other in the Levantine basin; both appear to have separated the warm water adjacent to the coast from the colder water in the interior of the basin. It is suggested that these two frontal zones may have been continuous and associated with the general counterclockwise circulation around the eastern Mediterranean basin.