Recent Changes in Eastern Mediterranean Deep Waters

Roether, Wolfgang; Manca, Beniamino B.; Klein, Birgit; Bregant, Davide; Georgopoulos, Dimitrios; Beitzel, Volker; Kovačević, Vedrana; Luchetta, Anna

doi:10.1126/science.271.5247.333

Cited by 655 publications

(513 citation statements)

References 6 publications

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“…1c). The presence of such a background abyssal current in the region is consistent with previous studies 5,6,13,14,20 suggesting that, as a part of the EMT, waters of Aegean origin replaced waters of Adriatic origin in the abyssal plain of the Ionian basin (see Fig. 1b).…”

Section: Resultssupporting

confidence: 91%

“…1b). Note that, in addition to this shift, which could belong to a part of a larger mode of variability of the EM 21 , a substantial mesoscale, interseasonal and interannual variability exists in EM water masses formation and circulation 5,6,13,14,20,22 .…”

Section: Resultsmentioning

confidence: 92%

“…During the EM Transient (EMT), a major climate shift that occurred at the end of the eighties and culminated in the nineties, relatively warm and salty abyssal waters of Aegean origin replaced colder and fresher Adriatic deep water (AdDW) in the bottom layers of the Ionian basin 5,6 . As a consequence, newly formed AdDW no longer possessed the density required to sustain its descent towards the Ionian abyss as a vein of bottom-arrested current as before the EMT.…”

mentioning

confidence: 99%

“…As a consequence, newly formed AdDW no longer possessed the density required to sustain its descent towards the Ionian abyss as a vein of bottom-arrested current as before the EMT. Instead, it had to intrude above waters of Aegean origin in the abyss of the northern and/or central Ionian basin 5 . This gave birth to profound transformations in the dynamics of AdDW and deep Aegean waters.…”

mentioning

confidence: 99%

“…Particularly, they can disintegrate into vortex chains, which can be advected by a background current [7][8][9][10][11] . Also as a consequence of such a complexity, in the Ionian basin, deep waters can differ considerably in their characteristics, dynamics and routes, which are partly determined by the underlying bathymetry 5 . Note also that the beginning of the new millennium can be considered as a period of large variability for water mass formation and stratification in the EM 5,6,[12][13][14][15][16] .…”

mentioning

confidence: 99%

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Abyssal undular vortices in the Eastern Mediterranean basin

et al. 2012

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Abyssal temperature and velocity observations performed within the framework of the neutrino mediterranean observatory, a project devoted to constructing a km 3 -scale underwater telescope for the detection of high-energy cosmic neutrinos, demonstrate cross-fertilization between subnuclear physics and experimental oceanography. Here we use data collected south of sicily in the Ionian abyssal plain of the Eastern mediterranean (Em) basin to show for the first time that abyssal vortices exist in the Em, at depths exceeding 2,500 m. The eddies consist of chains of near-inertially pulsating mesoscale cyclones/anticyclones. They are embedded in an abyssal current flowing towards north-northwest. The paucity of existing data does not allow for an unambiguous determination of the vortex origin. A local generation mechanism seems probable, but a remote genesis cannot be excluded a priori. The presence of such eddies adds further complexity to the discussion of structure and evolution of water masses in the Em.

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Section: Resultssupporting

confidence: 91%

Section: Resultsmentioning

confidence: 92%

mentioning

confidence: 99%

mentioning

confidence: 99%

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confidence: 99%

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Abyssal undular vortices in the Eastern Mediterranean basin

et al. 2012

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Solar forcing of Nile discharge and sapropel S1 formation in the early to middle Holocene eastern Mediterranean

et al. 2014

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We present high-resolution records for oxygen isotopes of the planktic foraminifer Globigerinoides ruber (δ 18 O ruber ) and bulk sediment inorganic geochemistry for Holocene-age sediments from the southeast Mediterranean. Our δ 18 O ruber record appears to be dominated by Nile discharge rather than basin-scale salinity/temperature changes. Nile discharge was enhanced in the early to middle Holocene relative to today. The timing of the long-term maximum in Nile discharge during the early Holocene corresponds to the timing of maximum intensity of the Indian Ocean-influenced Southwest Indian summer monsoon (SIM). This coincidence suggests a major influence of an Indian Ocean moisture source on Nile discharge in the early to middle Holocene, while, presently, the Atlantic Ocean is the main moisture source. Nile discharge was highly variable on multicentennial time scale during the early to middle Holocene, being strongly influenced by variable solar activity. This solar-driven variability is also recorded in contemporaneous SIM records, however, not observed in an Atlantic Ocean-derived West African summer monsoon record from the Holocene. This supports the hypothesis that the Indian Ocean moisture source predominantly controlled Nile discharge at that time. Solar-driven variability in Nile discharge also influenced paleoenvironmental conditions in the eastern Mediterranean. Bulk sediment Ba/Al and V/Al, used as indicators for (export) productivity and redox conditions, respectively, varied both in response to solar forcing on multicentennial time scales. We suggest that changes in Nile discharge on these time scales have been concordant with nutrient inputs to, and shallow ventilation of, the eastern Mediterranean.

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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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Recent Changes in Eastern Mediterranean Deep Waters

Cited by 655 publications

References 6 publications

Abyssal undular vortices in the Eastern Mediterranean basin

Abyssal undular vortices in the Eastern Mediterranean basin

Solar forcing of Nile discharge and sapropel S1 formation in the early to middle Holocene eastern Mediterranean

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

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