On the continuous functioning of an internal mechanism that drives the Eastern Mediterranean thermohaline circulation: The recent activation of the Aegean Sea as a dense water source area

Krokos, George; Velaoras, Dimitris; Κορρές, Γεράσιμος; Perivoliotis, L.; Theocharis, Alexander

doi:10.1016/j.jmarsys.2013.10.002

Cited by 34 publications

(36 citation statements)

References 18 publications

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“…Part of the arguments and assumptions presented in this work are based on a recent high-resolution hindcast numerical study of the 1960-2000 period , which showed the existence of a thermohaline internal mechanism that seems to prevail over atmospheric forcing in regulating dense water formation episodes (see section 2.3). Therefore, the assumptions for the 2000s decade presented herein are directly connected to the mechanism described by the aforementioned paper in conjunction with the work by Krokos et al [2014] which showed that the proposed mechanism is ongoing during the 2000s decade.…”

Section: Introductionmentioning

confidence: 71%

“…In this depth, the dissolved oxygen in station I01 reaches a local maximum as high as 5.08 ml/l which is almost 90% of the saturation value. We argue that this oxygen-rich dense water mass found in I01 has its origin in the mass found in 400-500 dbar in the Cretan Sea which after exiting the Antikythira straits settles deeper Krokos et al [2014] and CTD data presented in Gertman et al [2013] and Kress et al [2013]. Salinities according to these studies relax after 2009-2010 in the Levantine, while in the Cretan Sea the relaxation starts after 2010 as presented in paragraphs 4.1 and 4.2.1.…”

Section: Cretan Straits Exitmentioning

confidence: 76%

“…This strait is the deepest one and presents the main dense outflow among the western straits [Kontoyiannis et al, , 2005. Most casts in this area are chosen close to the southwest of the strait since dense masses after exiting tend to flow westwards along the slope under the influence of the Coriolis effect [Millot and Taupier-Letage, 2005] Krokos et al [2014] where a similar salinity trend is found in the first 300 dbars in the Eastern Levantine Basin and the Central Cretan Sea. These authors argue that the event is a manifestation of the internal thermohaline mechanism initially introduced by Theocharis et al [2014] that disturbs the EMed thermohaline conveyor belt.…”

Section: Cretan Straits Exitmentioning

confidence: 99%

“…The thermohaline pump mechanism proposed by Theocharis et al, [2014] differs from the BiOS mechanism proposed by Gačić et al [2010Gačić et al [ , 2011 Krokos et al [2014] showed that this pumping mechanism is an ongoing internal mechanism that led to the reactivation of the Aegean Sea during 2007-2009 almost a decade after the end of the EMT production period. Both Theocharis et al, [2014] and Krokos et al [2014] argue that the role of the internal mechanism seems to prevail over the long-term atmospheric influence in DWF events in the EMed.…”

Section: Deep Water In the Cretan Sea And The Eastern Mediterranean Tmentioning

confidence: 99%

“…Salinities according to these studies relax after 2009-2010 in the Levantine, while in the Cretan Sea the relaxation starts after 2010 as presented in paragraphs 4.1 and 4.2.1. The cause of these salinity changes is attributed by Krokos et al [2014] to an internal oscillating thermohaline mechanism which periodically disturbs the upper thermohaline EMed conveyor belt and alters the main water mass (AW/LIW) pathways.…”

Section: Cretan Straits Exitmentioning

confidence: 99%

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Dense intermediate water outflow from the Cretan Sea: A salinity driven, recurrent phenomenon, connected to thermohaline circulation changes

et al. 2014

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Data collected from different platforms in the Cretan Sea during the 2000s decade present evidence of gradually increasing salinity in the intermediate and deep intermediate layers after the middle of the decade. The observed gradual salt transport toward the deeper layers indicates contributions of dense water masses formed in various Aegean Sea subbasins. The accumulation of these saline and dense water masses in the Cretan Sea finally led to outflow from both Cretan Straits, with density greater than typical Levantine/Cretan Intermediate water but not dense enough to penetrate into the deep layers of the Eastern Mediterranean. We name this outflowing water mass as dense Cretan Intermediate Water (dCIW). A retrospective analysis of in situ data and literature references during the last four decades shows that similar events have occurred in the past in two occasions: (a) in the 1970s and (b) during the Eastern Mediterranean Transient (EMT) onset (1987)(1988)(1989)(1990)(1991). We argue that these salinity-driven Aegean outflows are mostly attributed to recurrent changes of the Eastern Mediterranean upper thermohaline circulation that create favorable dense water formation conditions in the Aegean Sea through salinity preconditioning. We identify these phenomena as ''EMT-like'' events and argue that in these cases internal thermohaline mechanisms dominate over atmospheric forcing in dense water production. However, intense atmospheric forcing over an already salinity preconditioned basin is indispensable for creating massive deep water outflow from the Cretan Sea, such as the EMT event.

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Section: Introductionmentioning

confidence: 71%

Section: Cretan Straits Exitmentioning

confidence: 76%

Section: Cretan Straits Exitmentioning

confidence: 99%

Section: Deep Water In the Cretan Sea And The Eastern Mediterranean Tmentioning

confidence: 99%

Section: Cretan Straits Exitmentioning

confidence: 99%

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Dense intermediate water outflow from the Cretan Sea: A salinity driven, recurrent phenomenon, connected to thermohaline circulation changes

et al. 2014

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A process study of the Adriatic‐Ionian System baroclinic dynamics

et al. 2016

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The driving mechanisms behind the decadal reversal of the Ionian Sea upper layer circulation recently sparked a considerable discussion in the Mediterranean scientific community. It has been suggested that the reversal can be driven by variations in wind stress curl over the basin, baroclinic dynamics acting within the Adriatic‐Ionian System (AISys) or baroclinic dynamics driven by thermohaline properties at the AISys eastern boundary. Here we perform numerical simulations in order to assess the relative importance of remote forcings (wind stress, thermohaline fluxes, thermohaline open boundary conditions) on the vorticity and energy budget of the Ionian Sea. A mechanistic understanding of the AISys dynamics is achieved with an approach based on an increasing complexity in the model forcings and domain. Our experiments suggest that wind stress does not play a leading role in the vorticity and energy budgets of the Ionian Sea. Wind stress can reinforce or weaken the circulation but it is not able to reverse its sign. Its role becomes dominant only in the absence of inflows through the Antikythira Strait and Cretan Passage. Instead, reversals in the upper layer circulation of the Ionian Sea take place only in the presence of an active boundary on the Aegean Sea/Levantine Basin side and appear to be correlated with substantial exchanges of Availalble Potential Energy between the two basins (as observed at the end of the Eastern Mediterranean Transient). From an energetic point of view, AISys can be explained therefore only if the role of the Aegean Sea is explicitly considered.

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Unexpected Covariant Behavior of the Aegean and Ionian Seas in the Period 1987–2008 by Means of a Nondimensional Sea Surface Height Index

et al. 2017

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In this work, we use a set of recent multiyear simulations to develop a simplified sea surface height index (SSH). The index characterizes the dynamics of Ionian upper layer circulation and its links with sea surface height and salinity in the Southern Adriatic and Aegean Seas during the period 1987–2008. The analysis highlights a covariant behavior between Ionian Sea and Aegean Sea associated with a mutual zonal exchange of water masses with different salinity characteristics. Our analysis confirms that the variability observed in the period 1987–2008 in the upper layer circulation of the Ionian was driven by the salinity variability in the Southern Adriatic and Aegean Sea. This study supports and reinforces the hypothesis that two observed BiOS‐like reversals reflect the existence of multiple equilibrium states in the Mediterranean Thermohaline circulation in the Eastern Mediterranean and that a complete characterization of observed variability needs to take into account a fully coupled Adriatic‐Ionian‐Aegean System.

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On the continuous functioning of an internal mechanism that drives the Eastern Mediterranean thermohaline circulation: The recent activation of the Aegean Sea as a dense water source area

Cited by 34 publications

References 18 publications

Dense intermediate water outflow from the Cretan Sea: A salinity driven, recurrent phenomenon, connected to thermohaline circulation changes

Dense intermediate water outflow from the Cretan Sea: A salinity driven, recurrent phenomenon, connected to thermohaline circulation changes

A process study of the Adriatic‐Ionian System baroclinic dynamics

Unexpected Covariant Behavior of the Aegean and Ionian Seas in the Period 1987–2008 by Means of a Nondimensional Sea Surface Height Index

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