The strait surface outflow

Self Cite

A low‐salinity anticyclonic eddy was found during a field study of the shelf/slope front off the northeast Spanish coast in July 1983. The eddy was associated with a tongue of low‐salinity, cold water that originated in the Gulf of Lions. Hydrographic stations indicated the presence of multiple salinity‐inversion layers. In particular, a relative salinity maximum layer was found at the base of the eddy, which can be traced through the study area along the same isopycnal surface. This suggests the thermohaline intrusion of near‐surface, warm, high‐salinity, open‐ocean water along the frontal boundary. The anticyclonic eddy also induced a strong up welling and, consequently, a high biological production at the coast. Subduction along the coastal front seems to provide major transport of particulate material into the open sea.

Section: This Remarkable Consistency Is Clear Evidence Of the Thermohmentioning

confidence: 85%

Eddies and thermohaline intrusions of the shelf/slope front off the northeast Spanish coast

Tintoré¹,

Wang²,

Violette³

1990

Self Cite

“…If U and f are constant and f> 0, the jet follows a circular clockwise (inertial) path with radius U/f If U decreases along the jet path as a result of entrainment, R will decrease, and an inertial spiral will result. Some support for such an inertial path is provided by numerical calculations [Wang, 1987], shown in Figure 6, and experiment [e.g., Flierl et al, 1983]. In Wang's case, -U/f--8 km, which is to be compared with -10 km, an approximately estimated value for R from Figure 6.…”

Section: For This Period a Solid Circle Indicates That A Satellite mentioning

confidence: 98%

Inertial wind path and sea surface temperature patterns near the Gulf of Tehuantepec and Gulf of Papagayo

Clarke¹

1988

During the northern hemisphere winter the surface atmospheric pressure on the Gulf of Mexico side of Central America is often higher than that on the Pacific side. The resultant southward pressure gradient drives strong southward winds through a gap in the Sierra Madre mountain range at the Isthmus of Tehuantepec. The atmospheric jet is narrow in comparison with the relevant radius of deformation, so when it leaves the coast and flows out over the Gulf of Tehuantepec, it is an inertial jet. Therefore the jet is expected to be deflected into a clockwise inertial circle by the Coriolis force. A similar process should also occur for Central American atmospheric jets through mountain range gaps near the Gulf of Papagayo. Satellite measurements of sea surface temperature together with coastal wind data for the first 41 days of 1986 were examined to see if the expected wind path influenced sea surface temperature (SST) near the Gulf of Tehuantepec and the Gulf of Papagayo. Consecutive daily satellite images when the coastal southward Tehuantepec wind increased suggest that the initial development of cold surface water in a clockwise loop is due to the wind mixing the shallow thermocline surface water along its inertial path. A simple l«-layer analytical ocean model suggests, in agreement with observations, that the wind can drive surface quasi-geostrophic currents of --• 1 m s -•. Since the wind path is circular, the wind actually generates a clockwise rotating ocean eddy with the approximate scale of the wind inertial circle. The satellite sea surface temperature measurements also suggest that the wind-driven surface ocean current is unstable. In addition, stronger gradients in SST to the right of the expected wind flow are consistent with advection of sea surface temperature by ocean surface Ekman flow.

“…Table 1 for this study are rather approximate because of mixing that occurs before the surface layer leaves the strait. Wang [1987] also adapted a three-dimensional primitive equation model, with simplified geometry, to consider both momentum and buoyancy effects. The relative vorticity was negative because of upward motion in the adjustment process.…”

Section: Introductionmentioning

confidence: 99%

A simple criterion for gyre formation by the surface outflow from a strait, with application to the Alboran Sea

Bormans¹,

Garrett²

1989

A survey of relevant numerical, laboratory, and observational studies, combined with our own laboratory experiments, suggests that the surface outflow from a strait generally forms a gyre in the adjacent sea if the exit corner is sharp. The gyre grows from an initial “separation bubble” of radius u/f, where u is the current speed and f the Coriolis frequency. The criterion for the maintenance of a coastal jet along a curved coast, instead of separation and gyre formation, seems to be that the Rossby number u(fRw)−1 < 1, with Rw the radius of curvature of the exit corner, so that the Coriolis force can hold the current to the coast. This synthesis disregards factors such as the variation of u across the current but, applied to the flow through the Strait of Gibraltar into the Alboran Sea, suggests that a gyre should always form as the exit corner is sharp. We suggest, though, that the relevant curvature is that where the interface between the two layers intersects the seafloor rather than where the sea surface meets the coast. If this is the case, supercritical flow or some subcritical flows at the eastern end of the Strait should still always lead to gyre formation, but the observed replacement of the gyre by a coastal jet along the Moroccan coast could be related to subcritical flow that is reduced below its normal value by a barotropic fluctuation or by changes in the interface depth in the Mediterranean.