The Mediterranean outflow in the Strait of Gibraltar and its connection with upstream conditions in the Alborán Sea

García‐Lafuente, Jesús; Naranjo, Cristina; Sammartino, Simone; Garrido, José Carlos Sánchez; Delgado, Javier

doi:10.5194/os-13-195-2017

Cited by 28 publications

(18 citation statements)

References 30 publications

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“…A more subtle question is why signals are much better seen in θ min than in S series (for instance, the annual response to the deep convection), when the WMT was triggered by the LIW salinification during the late 90s and first years of this century rather than by cooling [ Schroeder et al ., ]. As discussed in García‐Lafuente et al [], the reason is that at monthly to annual time scales, a fraction as small as 5% of NACW in the MOW is able to obliterate salinity signals coming from the WMb; only long‐term salinity changes would show up. This does not apply to temperature, since the temperature difference between the NACW and the underlying MWs is much less than for salinity.…”

Section: Discussionmentioning

confidence: 99%

Recent changes (2004–2016) of temperature and salinity in the Mediterranean outflow

Naranjo

García‐Lafuente

Sammartino

et al. 2017

Geophysical Research Letters

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Temperature and salinity series near the seafloor at Espartel Sill (Strait of Gibraltar) have been used to analyze the thermohaline variability of the Mediterranean outflow. The series shows temperature drops by the end of most winters/early springs, which are the remote response to Western Mediterranean Deep Water (WMDW) formation events in the Gulf of Lion that uplift old WMDW nearby the strait. This process distorts the seasonal cycle of colder/warmer water flowing out in summer/winter likely linked to the seasonality of the Western Alborán Gyre. The series shows positive trends in agreement with previous values, which are largely increased after 2013. It is tentatively interpreted as the Western Mediterranean Transition (WMT) signature that started with the very cold winters of 2005 and 2006. It was only after the large new WMDW production of 2012 and 2013 harsh winters that WMT waters were made available to flow out of the Mediterranean Sea.

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Section: Discussionmentioning

confidence: 99%

Recent changes (2004–2016) of temperature and salinity in the Mediterranean outflow

Naranjo

García‐Lafuente

Sammartino

et al. 2017

Geophysical Research Letters

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“…The MOW at the exit of the Strait of Gibraltar is a salty, high‐density current formed by a mixture of LIW and WMDW with an average salinity and temperature of 38.4 psu and 13°C, respectively (Figure 1) (Bryden & Stommel, 1982; Garcia‐Lafuente et al, 2017; Gasser et al, 2017; Hernández‐Molina et al, 2014; Millot, 2014; Sanchez‐Leal et al, 2017). After crossing the Camarinal Sill in the Strait of Gibraltar, at 290 m water depth, this dense MOW cascades down into the Gulf of Cadiz, as an overflow (Legg et al, 2009), accelerating because of its density anomaly and mixes and entrains the overlying fresher eastern North Atlantic central water (ENACW).…”

Section: Mow and Ne Atlantic Circulation Todaymentioning

confidence: 99%

Mediterranean Overflow Over the Last 250 kyr: Freshwater Forcing From the Tropics to the Ice Sheets

Sierro

Hodell

Andersen

et al. 2020

Paleoceanog and Paleoclimatol

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To investigate past changes in the Mediterranean Overflow Water (MOW) to the Atlantic, we analyzed the strength of the MOW and benthic δ 13 C along the last 250 kyr at Integrated Ocean Drilling Program (IODP) Site U1389 in the Gulf of Cadiz, near the Strait of Gibraltar. Both the strength of the MOW and the benthic δ 13 C were mainly driven by precession-controlled fluctuations in the Mediterranean hydrologic budget. Reduced/enhanced Nile discharge and lower/higher Mediterranean annual rainfall at precession maxima/minima resulted in higher/lower MOW strengths at Gibraltar and stronger/weaker Mediterranean overturning circulation. At millennial scale, the higher heat and freshwater loss to the atmosphere during Greenland stadials increased buoyancy loss in the eastern Mediterranean. This enhanced the density gradient with Atlantic water, resulting in a higher MOW velocity in the Gulf of Cadiz. Unlike non-Heinrich stadials, a lower-amplitude increase in velocity was seen during Heinrich stadials (HSs), and a significant drop in velocity was recorded in the middle phase. This weak MOW was especially recognized in Termination I and II during HS1 and HS11. These lower velocities at the depth of Site U1389 were triggered by MOW deepening due to the lower densities of Atlantic intermediate water caused by freshwater released from the Laurentide and Eurasian ice sheets. The intrusion of salt and heat at deeper depths in the Atlantic during HSs and its shoaling at the end could have contributed to drive the changes in the Atlantic Meridional Overturning Circulation during Terminations.

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“…Roughly, the water mass structure is close to a two-layer system characterized by an upper surface layer of Atlantic waters entering into the basin and denser Mediterranean waters outflowing below [9]. The inflow of Atlantic water and the outflow of Mediterranean water are constrained by hydraulic control in the channel where the bottom relief, stratification, tidal, and wind regimes determine the variability of water exchanges through the strait, which are therefore linked to basin scale variability, e.g., [10,11].…”

Section: Introductionmentioning

confidence: 98%

Real-time Reconstruction of Surface Velocities from Satellite Observations in the Alboran Sea

et al. 2020

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Surface currents in the Alboran Sea are characterized by a very fast evolution that is not well captured by altimetric maps due to sampling limitations. On the contrary, satellite infrared measurements provide high resolution synoptic images of the ocean at high temporal rate, allowing to capture the evolution of the flow. The capability of Surface Quasi-Geostrophic (SQG) dynamics to retrieve surface currents from thermal images was evaluated by comparing resulting velocities with in situ observations provided by surface drifters. A difficulty encountered comes from the lack of information about ocean salinity. We propose to exploit the strong relationship between salinity and temperature to identify water masses with distinctive salinity in satellite images and use this information to correct buoyancy. Once corrected, our results show that the SQG approach can retrieve ocean currents slightly better to that of near-real-time currents derived from altimetry in general, but much better in areas badly sampled by altimeters such as the area to the east of the Strait of Gibraltar. Although this area is far from the geostrophic equilibrium, the results show that the good sampling of infrared radiometers allows at least retrieving the direction of ocean currents in this area. The proposed approach can be used in other areas of the ocean for which water masses with distinctive salinity can be identified from satellite observations.

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The Mediterranean outflow in the Strait of Gibraltar and its connection with upstream conditions in the Alborán Sea

Cited by 28 publications

References 30 publications

Recent changes (2004–2016) of temperature and salinity in the Mediterranean outflow

Recent changes (2004–2016) of temperature and salinity in the Mediterranean outflow

Mediterranean Overflow Over the Last 250 kyr: Freshwater Forcing From the Tropics to the Ice Sheets

Real-time Reconstruction of Surface Velocities from Satellite Observations in the Alboran Sea

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