scholarly journals Levantine Intermediate and Levantine Deep Water Formation: An Argo Float Study from 2001 to 2017

Water ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 1781 ◽  
Author(s):  
Elisabeth Kubin ◽  
Pierre-Marie Poulain ◽  
Elena Mauri ◽  
Milena Menna ◽  
Giulio Notarstefano
Keyword(s):  
Deep Water ◽  
Eastern Mediterranean ◽  
Potential Temperature ◽  
Sea Surface ◽  
Intermediate Water ◽  
Deep Water Formation ◽  
Argo Float ◽  
Levantine Sea ◽  
Water Formation ◽  
The Mediterranean

Levantine intermediate water (LIW) is formed in the Levantine Sea (Eastern Mediterranean) and spreads throughout the Mediterranean at intermediate depths, following the general circulation. The LIW, characterized by high salinity and relatively high temperatures, is one of the main contributors of the Mediterranean Overturning Circulation and influences the mechanisms of deep water formation in the Western and Eastern Mediterranean sub-basins. In this study, the LIW and Levantine deep water (LDW) formation processes are investigated using Argo float data from 2001 to 2017 in the Northwestern Levantine Sea (NWLS), the larger area around Rhodes Gyre (RG). To find pronounced events of LIW and LDW formation, more than 800 Argo profiles were analyzed visually. Events of LIW and LDW formation captured by the Argo float data are compared to buoyancy, heat and freshwater fluxes, sea surface height (SSH), and sea surface temperature (SST). All pronounced events (with a mixed layer depth (MLD) deeper than 250 m) of dense water formation were characterized by low surface temperatures and strongly negative SSH. The formation of intermediate water with typical LIW characteristics (potential temperature > 15 °C, salinity > 39 psu) occurred mainly along the Northern coastline, while LDW formation (13.7 °C < potential temperature < 14.5 °C, 38.8 psu < salinity < 38.9 psu) occurred during strong convection events within temporary and strongly depressed mesoscale eddies in the center of RG. This study reveals and confirms the important contribution of boundary currents in ventilating the interior ocean and therefore underlines the need to rethink the drivers and contributors of the thermohaline circulation of the Mediterranean Sea.

scholarly journals The Mediterranean is getting saltier

2014 ◽  
Vol 11 (1) ◽  
pp. 735-752 ◽  
Author(s):  
M. Borghini ◽  
H. Bryden ◽  
K. Schroeder ◽  
S. Sparnocchia ◽  
A. Vetrano
Keyword(s):  
Deep Water ◽  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Intermediate Water ◽  
Deep Water Formation ◽  
The Past ◽  
Deep Waters ◽  
Western Mediterranean Basin ◽  
Water Formation ◽  
The Mediterranean

Abstract. The deep waters of the Mediterranean Sea have been getting saltier and warmer for at least the past 40 yr at rates of about 0.015 and 0.04 °C per decade. Here we show that two processes contribute to these increases in temperature and salinity. On interannual time scales, deep water formation events in severe winters transmit increasingly salty intermediate waters into the deep water. The second process is a steady downward flux of heat and salt through the halocline-thermocline that connects the Levantine Intermediate Water with the deep water. We illustrate these two processes with observations from repeat surveys of the western Mediterranean basin we have made over the past 10 yr.

scholarly journals Changes in ventilation of the Mediterranean Sea during the past 25 year

Ocean Science ◽  
2014 ◽  
Vol 10 (1) ◽  
pp. 1-16 ◽  
Author(s):  
A. Schneider ◽  
T. Tanhua ◽  
W. Roether ◽  
R. Steinfeldt
Keyword(s):  
Mediterranean Sea ◽  
Deep Water ◽  
Adriatic Sea ◽  
Western Mediterranean ◽  
Tyrrhenian Sea ◽  
Deep Water Formation ◽  
Technical Problems ◽  
Water Formation ◽  
The Mediterranean ◽  
Transient Tracer

Abstract. Significant changes in the overturning circulation of the Mediterranean Sea has been observed during the last few decades, the most prominent phenomena being the Eastern Mediterranean Transient (EMT) in the early 1990s and the Western Mediterranean Transition (WMT) during the mid-2000s. During both of these events unusually large amounts of deep water were formed, and in the case of the EMT, the deep water formation area shifted from the Adriatic to the Aegean Sea. Here we synthesize a unique collection of transient tracer (CFC-12, SF6 and tritium) data from nine cruises conducted between 1987 and 2011 and use these data to determine temporal variability of Mediterranean ventilation. We also discuss biases and technical problems with transient tracer-based ages arising from their different input histories over time; particularly in the case of time-dependent ventilation. We observe a period of low ventilation in the deep eastern (Levantine) basin after it was ventilated by the EMT so that the age of the deep water is increasing with time. In the Ionian Sea, on the other hand, we see evidence of increased ventilation after year 2001, indicating the restarted deep water formation in the Adriatic Sea. This is also reflected in the increasing age of the Cretan Sea deep water and decreasing age of Adriatic Sea deep water since the end of the 1980s. In the western Mediterranean deep basin we see the massive input of recently ventilated waters during the WMT. This signal is not yet apparent in the Tyrrhenian Sea, where the ventilation seems to be fairly constant since the EMT. Also the western Alboran Sea does not show any temporal trends in ventilation.

scholarly journals Changes in Mediterranean circulation and water characteristics due to restriction of the Atlantic connection: a high-resolution ocean model

2015 ◽  
Vol 11 (2) ◽  
pp. 233-251 ◽  
Author(s):  
R. P. M. Topper ◽  
P. Th. Meijer
Keyword(s):  
Deep Water ◽  
Ocean Model ◽  
Messinian Salinity Crisis ◽  
Deep Water Formation ◽  
Western Basin ◽  
Eastern Basin ◽  
Water Characteristics ◽  
Water Formation ◽  
Sill Depth ◽  
The Mediterranean

Abstract. A high-resolution parallel ocean model is set up to examine how the sill depth of the Atlantic connection affects circulation and water characteristics in the Mediterranean Basin. An analysis of the model performance, comparing model results with observations of the present-day Mediterranean, demonstrates its ability to reproduce observed water characteristics and circulation (including deep water formation). A series of experiments with different sill depths in the Atlantic–Mediterranean connection is used to assess the sensitivity of Mediterranean circulation and water characteristics to sill depth. Basin-averaged water salinity and, to a lesser degree, temperature rise when the sill depth is shallower and exchange with the Atlantic is lower. Lateral and interbasinal differences in the Mediterranean are, however, largely unchanged. The strength of the upper overturning cell in the western basin is proportional to the magnitude of the exchange with the Atlantic, and hence to sill depth. Overturning in the eastern basin and deep water formation in both basins, on the contrary, are little affected by the sill depth. The model results are used to interpret the sedimentary record of the Late Miocene preceding and during the Messinian Salinity Crisis. In the western basin, a correlation exists between sill depth and rate of refreshment of deep water. On the other hand, because sill depth has little effect on the overturning and deep water formation in the eastern basin, the model results do not support the notion that restriction of the Atlantic–Mediterranean connection may cause lower oxygenation of deep water in the eastern basin. However, this discrepancy may be due to simplifications in the surface forcing and the use of a bathymetry different from that in the Late Miocene. We also tentatively conclude that blocked outflow, as found in experiments with a sill depth &amp;leq;10 m, is a plausible scenario for the second stage of the Messinian Salinity Crisis during which halite was rapidly accumulated in the Mediterranean. With the model setup and experiments, a basis has been established for future work on the sensitivity of Mediterranean circulation to changes in (palaeo-)bathymetry and external forcings.

scholarly journals The Mediterranean is becoming saltier

Ocean Science ◽  
2014 ◽  
Vol 10 (4) ◽  
pp. 693-700 ◽  
Author(s):  
M. Borghini ◽  
H. Bryden ◽  
K. Schroeder ◽  
S. Sparnocchia ◽  
A. Vetrano
Keyword(s):  
Deep Water ◽  
Mediterranean Basin ◽  
Western Mediterranean ◽  
Intermediate Water ◽  
Deep Water Formation ◽  
The Past ◽  
Western Mediterranean Sea ◽  
Deep Waters ◽  
Western Mediterranean Basin ◽  
Water Formation

Abstract. The deep waters of the western Mediterranean Sea have become saltier and warmer for at least the past 40 years at rates of about 0.015 and 0.04 °C per decade. Here we show that two processes contribute to these increases in temperature and salinity. On interannual timescales, deep water formation events in severe winters transmit increasingly salty intermediate waters into the deep water. The second process is a steady downward flux of heat and salt associated with salt finger mixing down through the halocline–thermocline that connects the Levantine Intermediate Water with the deep water. We illustrate these two processes with observations from repeat surveys of the western Mediterranean basin we have made over the past 10 years.

Climatic forcing of eastern Mediterranean deep-water formation and benthic ecosystems during the past 22 000 years

2010 ◽  
Vol 29 (23-24) ◽  
pp. 3006-3020 ◽  
Author(s):  
Gerhard Schmiedl ◽  
Tanja Kuhnt ◽  
Werner Ehrmann ◽  
Kay-Christian Emeis ◽  
Yvonne Hamann ◽  
...  
Keyword(s):  
Deep Water ◽  
Eastern Mediterranean ◽  
Deep Water Formation ◽  
Climatic Forcing ◽  
The Past ◽  
Water Formation ◽  
Benthic Ecosystems
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