Contents lists available at ScienceDirect Deep-Sea Research Part II journal homepage: www.elsevier.com/locate/dsr2 Water masses and hydrography during April and June 2016 in the Cretan Sea and Cretan Passage (Eastern Mediterranean Sea) Dimitris Velaoras a, ⁎ , Vassilis P. Papadopoulos a , Harilaos Kontoyiannis a , Vanessa Cardin b , Giuseppe Civitarese b a Hellenic Centre for Marine Research (HCMR), Institute of Oceanography, 46.7km Athens – Sounio Avenue, 19013 Anavyssos, Greece b Istituto Nazionale di Oceanografia e di Geofisica Sperimentale (OGS), Borgo Grotta Gigante 42/C, 34010 Sgonico (TS), Italy ARTICLEINFO Keywords: Eastern Mediterranean Sea Cretan Sea Cretan Passage West Levantine basin Descriptive physical oceanography Water masses Water circulation Current observations 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 confrm that the hydrographical status is far diferent 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 be- tween intermediate and bottom layers throughout the Cretan Sea. Intermittent weak outfow 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. 1. Introduction The Mediterranean Sea, often referred to as a “miniature ocean” due to the complexity and multiplicity of the oceanic processes it hosts, is known to be a semi-enclosed oceanic basin where evaporation largely exceeds precipitation and river run-of (Pickard and Emery, 1990), i.e., a concentration-type basin. As a result, low salinity/density Atlantic Water (AW) enters through the Straits of Gibraltar in order to com- pensate the water defcit of the basin. The Eastern Mediterranean Sea (EMed) is the part of the Mediterranean where AW is converted into a more saline and dense intermediate water mass known as Levantine Intermediate Water (LIW). This is done by winter open-sea convection processes at its easternmost part (Levantine Basin), (POEM Group, 1992; Robinson et al., 2001). AW enters the EMed through the Strait of Sicily as a surface/subsurface eastward fow (~0–150 m) while a return LIW westward fow at intermediate depths (~150–400 m) closes the upper thermohaline conveyor belt of the EMed. Consequently, an anti- estuarine circulation, typical for a concentration basin, is developed at the Strait of Sicily which acts as the “choke point” for the EMed, much in the same way that the Straits of Gibraltar function for the whole Mediterranean Sea. Thus, it can be argued that the EMed simulates a miniature Mediterranean inside the wider Mediterranean Sea that ad- ditionally encloses the main thermohaline engine of the whole basin. The deep thermohaline cell of the EMed is regulated by two Dense Water Formation (DWF) areas (Pollak, 1951; Robinson et al., 2001): the Adriatic Sea, which is considered as the main deep water source, and the Aegean Sea, which has been reported as a sporadic deep water contributor although it is mainly an intermediate water formation area. DWF during the late ‘80 s – early ‘90 s decade in the latter led to the Eastern Mediterranean Transient (EMT), i.e., the massive outfow of deep water from the southern part of the Aegean (Cretan Sea) that gradually replaced the Adriatic Deep Water (ADW) in the bottom EMed layers (Roether et al., 1996; Theocharis et al., 1999a). Since then, the Eastern Mediterranean Deep Water (EMDW) became a mixture of deep water produced in the Aegean Sea during the EMT and new ADW produced in the Adriatic after the event (Roether et al., 2007; https://doi.org/10.1016/j.dsr2.2018.09.005 Received 7 May 2018; Accepted 7 September 2018 ⁎ Corresponding author. E-mail address: dvelaoras@hcmr.gr (D. Velaoras). Deep-Sea Research Part II xxx (xxxx) xxx–xxx 0967-0645/ © 2018 Elsevier Ltd. All rights reserved. Please cite this article as: Velaoras, D., Deep-Sea Research Part II, https://doi.org/10.1016/j.dsr2.2018.09.005