Circulation and Exchange in Choked Marginal Seas

Pratt, Lawrence J.; Spall, Michael A.

doi:10.1175/2008jpo3946.1

Cited by 15 publications

(17 citation statements)

References 23 publications

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“…To our knowledge, this is the first simulation of sinking along the boundaries of a realistic basin and it is a step forward in understanding buoyancy‐driven circulation, not only in the Red Sea but also in other marginal seas. The sinking process along the boundary is also supported by previous idealized, analytical and experimental studies [ Spall and Pickart , ; Spall , ; Pratt and Spall , ; Pedlosky and Spall 2005; Cenedese , ]. These comparisons give us confidence that the sinking process as suggested in the model is physically plausible.…”

Section: Discussionsupporting

confidence: 82%

Seasonal overturning circulation in the Red Sea: 2. Winter circulation

Yao

Hoteit

Pratt

et al. 2014

J. Geophys. Res. Oceans

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102

166

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The shallow winter overturning circulation in the Red Sea is studied using a 50 year highresolution MITgcm (MIT general circulation model) simulation with realistic atmospheric forcing. The overturning circulation for a typical year, represented by 1980, and the climatological mean are analyzed using model output to delineate the three-dimensional structure and to investigate the underlying dynamical mechanisms. The horizontal model circulation in the winter of 1980 is dominated by energetic eddies. The climatological model mean results suggest that the surface inflow intensifies in a western boundary current in the southern Red Sea that switches to an eastern boundary current north of 24 N. The overturning is accomplished through a cyclonic recirculation and a cross-basin overturning circulation in the northern Red Sea, with major sinking occurring along a narrow band of width about 20 km along the eastern boundary and weaker upwelling along the western boundary. The northward pressure gradient force, strong vertical mixing, and horizontal mixing near the boundary are the essential dynamical components in the model's winter overturning circulation. The simulated water exchange is not hydraulically controlled in the Strait of Bab el Mandeb; instead, the exchange is limited by bottom and lateral boundary friction and, to a lesser extent, by interfacial friction due to the vertical viscosity at the interface between the inflow and the outflow.

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Section: Discussionsupporting

confidence: 82%

Seasonal overturning circulation in the Red Sea: 2. Winter circulation

Yao

Hoteit

Pratt

et al. 2014

J. Geophys. Res. Oceans

Self Cite

102

166

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show abstract

“…Data and simple modelling studies have demonstrated the importance of the size of the Atlantic-Mediterranean connection in controlling sedimentation and circulation in the Mediterranean. Recently, ocean circulation models have been used to investigate the influence of gateway geometry on water characteristics and circulation in an idealized marginal basin (Iovino et al, 2008;Pratt and Spall, 2008) and realistic marginal basins, e.g. the Miocene Arctic Ocean (Thompson et al, 2010).…”

Section: R P M Topper and P Th Meijer: Mediterranean Response Tomentioning

confidence: 99%

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

Topper

Meijer

2015

Clim. Past

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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 MediterraneanBasin. 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 ≤ 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.

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“…An annual cycle of sea-surface cooling of 6. The case of hydraulically controlled exchange between an open ocean and a marginal sea with cyclonic boundary currents is considered by Pratt and Spall (2008).…”

mentioning

confidence: 99%

On the effect of a sill on dense water formation in a marginal sea

Iovino¹,

Straneo²,

Spall³

2008

J Mar Res

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The properties of water mass transformation in a semi-enclosed basin, separated from the open ocean by a sill and subject to surface cooling, are analyzed both theoretically and numerically using an ocean general circulation model. This study extends previous studies of convection in a marginal sea to the case with a sill.The sill has a strong impact on both the properties of the dense water formed in the interior and on those of the waters flowing out the marginal sea. It results in a colder interior and colder outflow compared to the case with no sill. Dynamically, this is explained by considering that the sill limits the geostrophic contours over which the open ocean/marginal sea exchange can occur. The impact of the sill, however, is not simply limited to a topographic constriction; instead the sill also decreases the stability of the boundary current, which, in turn, results in relatively large heat flux into the interior and colder outflow.The theories that relate the properties of the dense waters formed in the interior, and those of the outflow, are modified to include the impact of the sill. These are found to compare well with the numerical simulations and provide a useful tool for the interpretation of these results. These idealized simulations capture the basic features of the water mass transformation processes in the Nordic Seas and, in particular, provide a dynamical explanation for the difference between the dense waters formed and the source of the overflows water.

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Circulation and Exchange in Choked Marginal Seas

Cited by 15 publications

References 23 publications

Seasonal overturning circulation in the Red Sea: 2. Winter circulation

Seasonal overturning circulation in the Red Sea: 2. Winter circulation

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

On the effect of a sill on dense water formation in a marginal sea

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