Water masses and hydrography during April and June 2016 in the Cretan Sea and Cretan Passage (Eastern Mediterranean Sea)

Abstract

Two successive cruises in the Cretan Sea and Cretan Passage (West Levantine basin) during April and June 2016 surveyed the physical characteristics of the water masses in these large Eastern Mediterranean basins. Data confirm that the hydrographical status is far different from that of the Eastern Mediterranean Transient (EMT) period; however, the basins have not yet returned to the pre-EMT status. In the Cretan Sea, intermediate water masses of both Cretan and Levantine origins are detected. The stagnating bottom waters of this basin still hold high salinity, density, and dissolved oxygen values, remnant of the EMT deep water formation episodes. Characterised by low salinity and oxygen values, transitional waters of Mediterranean origin are present between intermediate and bottom layers throughout the Cretan Sea. Intermittent weak outflow of warm and saline masses of Cretan origin towards the Eastern Mediterranean is observed at the bottom of both east and west Cretan Straits. In the Cretan Passage, there is no sign of the Ierapetra anticyclonic gyre, possibly related to the seasonality of the gyre or linked to larger scale Eastern Mediterranean circulation variability. The observed surface circulation in this area is comprised of a series of smaller gyres between the Cretan Cyclone and the Rhodes Gyre. The bottom waters of the Cretan Passage present a west-to-east gradient of increasing salinity and decreasing oxygen related to the propagation of new Adriatic Deep Water from the Ionian Sea towards the Levantine basin.