Thermohaline properties in the Eastern Mediterranean in the last three decades: is the basin returning to the pre-EMT situation?

Abstract

Abstract. Temperature, salinity and oxygen data collected during April and June 2011 (M84/3 and P414 cruises respectively) are analysed to derive the oceanographic characteristics of the Eastern Mediterranean (EM) basin. These observed characteristics are compared with those from previous cruises over the period 1987-2011. As a result, the interannual and decadal variability of the EM thermohaline properties are discussed in the context of the evolution of the Eastern Mediterranean Transient (EMT) and of the general circulation of the basin. We found that the state of the EM is still far from the pre-EMT conditions, though the 2011 results possibly indicate a slow return to this status. In particular, a comparison between thermohaline property evolution deriving from interannual variability of the preconditioning and air-sea interaction (heat fluxes) in the South Adriatic and the Cretan Seas reveals aspects of the alternation of the two dense water sources (Adriatic and Aegean) during the last three decades, which have strong implications for the hydrographic characteristics of the intermediate and deep layers of the Ionian and Levantine basins.

Effects of the Eastern Mediterranean Sea circulation on the thermohaline properties as recorded by fixed deep-ocean observatories

“…Consequently, there was a freshening of the Ionian basin accompanied by a respective salinity increase in the Aegean Sea that favoured DWF in that basin. By 1999, the AW pathway had re-established its eastward flow towards the Levantine (Theocharis et al, 2002), and the EMed has gradually been returning to its previous state with the Adriatic Sea as the main DWF source (Rubino and Hainbucher, 2007;Bensi et al, 2013;Cardin et al, 2015;Meccia et al, 2015).…”

Comparison of high resolution hydrodynamic model outputs with in-situ Argo profiles in the Ionian Sea

“…Furthermore, at the south-eastern part of the basin, dense water outflow has been recorded during 2009 from the Aegean Sea, that followed a northward path along the Hellenic Trench giving a signal of increased salinity in the intermediate layers . This outflow was the result of the preconditioned for dense water formation status of the Aegean that has been reported for the period 2007-2012 (Schroeder et al, 2013;Krokos et al, 2014;Cardin et al, 2015;Kassis et al, 2015) and resulted in the alternation of the southeastern Ionian upper and intermediate waters. The aforementioned short term inter-annual changes in the area's hydrography create a challenging field for the performance of numerical hydrodynamic simulations.…”

A process study of the Adriatic‐Ionian System baroclinic dynamics

“…Since 1997 the additional salinity supply into SA acts as favorable preconditioning for higher density DWF in this area. This would facilitate the ventilation of the bottom layers of the Ionian as before 1987 [ Klein et al ., ] despite recent evidences show that thermohaline properties in the Ionian are still far from those observed in the pre‐EMT phase [ Cardin et al ., ].…”