Climatic changes in the Aegean Sea influence the eastern Mediterranean thermohaline circulation (1986–1997)

Theocharis, Alexander; Nittis, K.; Kontoyiannis, Harilaos; Papageorgiou, Emanuel; Balopoulos, E.

doi:10.1029/1999gl900320

Cited by 218 publications

(211 citation statements)

References 7 publications

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“…However, since the (small) Aegean-Ionian flux pre 1990 is unknown we are unable to approximate k 2 . On the other hand, it was reported that the temperature over the Aegean basin dropped by 2 • C during several winters after 1990 [16,19]. We note that most bottom water is formed in winter.…”

Section: Parameter Choicesmentioning

confidence: 97%

“…This state is sensitive to changes in atmospheric temperature that may drastically change the strength of the deep water formation source over the Aegean. Indeed, cold winters were observed over the Aegean before and during the EMT [15,16,17].…”

Section: Discussionmentioning

confidence: 99%

“…(26), (27) the expressions for the fluxes q 1 (T 1 ) and q 2 (T 2 ) [Eqs. (16), (18)], we are left with two high order coupled equations for the equilibrium temperatures T 1 and T 2 . In the following we will use the approximations [Eqs.…”

Section: Variable Temperaturesmentioning

confidence: 99%

“…One study suggested that enhanced net evaporation led to the formation of the new Aegean source [14]. In addition, the north Eastern Mediterranean experienced some cold winters during the 1987-1995 period and these have been associated with changes in the thermohaline circulation throughout the region [15,16,17]. However, the lack of oceanic data during 1987-1995 makes it difficult to uncover the exact cause for the formation of the new Aegean source.…”

Section: Introductionmentioning

confidence: 99%

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Box modeling of the Eastern Mediterranean sea

Ashkenazy

Stone

Malanotte‐Rizzoli

2012

Physica A: Statistical Mechanics and its Applications

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In ∼1990 a new source of deep water formation in the Eastern Mediterranean was found in the southern part of the Aegean sea. Till then, the only source of deep water formation in the Eastern Mediterranean was in the Adriatic sea; the rate of the deep water formation of the new Aegean source is 1 Sv, three times larger than the Adriatic source. We develop a simple three box-model to study the stability of the thermohaline circulation of the Eastern Mediterranean sea. The three boxes represent the Adriatic sea, Aegean sea, and the Ionian seas. The boxes exchange heat and salinity and may be described by a set of nonlinear differential equations. We analyze these equations and find that the system may have one, two, or four stable flux states. We conjecture that the change in the deep water formation in the Eastern Mediterranean sea is attributed to a switch between the different states on the thermohaline circulation; this switch may result from decreased temperature and/or increased salinity over the Aegean sea.

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Section: Parameter Choicesmentioning

confidence: 97%

Section: Discussionmentioning

confidence: 99%

Section: Variable Temperaturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Box modeling of the Eastern Mediterranean sea

Ashkenazy

Stone

Malanotte‐Rizzoli

2012

Physica A: Statistical Mechanics and its Applications

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“…However, it was not until Schlitzer et al [1991] named these intermediate masses of Cretan Sea origin as Cretan Intermediate Water (CIW) that they were identified as a distinguishable water mass. Inside the Cretan Sea, CIW compared to LIW is generally considered being slightly colder, more saline, and denser [Astraldi et al, 1999;Theocharis et al, 1999b]. After exiting the Cretan Straits, CIW settles at depths between the LIW horizon and Eastern Mediterranean Deep Water (EMDW) [Schlitzer at al., 1991;Roether et al, 1999] and moves westward along the Cretan continental slope toward the Ionian and Adriatic Seas Theocharis et al, 2002a;Manca et al, 2006;Millot, 2013] finally providing salt to the latter.…”

Section: Surface and Intermediate Masses And Circulationmentioning

confidence: 99%

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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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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Climatic changes in the Aegean Sea influence the eastern Mediterranean thermohaline circulation (1986–1997)

Cited by 218 publications

References 7 publications

Box modeling of the Eastern Mediterranean sea

Box modeling of the Eastern Mediterranean sea

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

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