The role of temperature inversions in the mixing processes of the deep ocean

Howe, M.R.; Tait, R.I.

doi:10.1016/0011-7471(72)90098-8

Cited by 5 publications

(5 citation statements)

References 13 publications

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“…In the interfaces above and below such a layer the nearly compensating gradients of T and S are in the diffusive and finger senses, respectively. Moreover, Howe and Tait [1972] showed that the net density gradient at the top of the intrusions that they observed was typically 10 times as large as that at the bottom, and this tendency for the gradients to be very unequal has been confirmed by Gargett [1976]. This is in accord with our visual observations in the laboratory and is consistent with the idea that double-diffusive convection is active between the alternating layers and is maintaining sharp diffusive interfaces above and more diffuse finger interfaces below the intrusions.…”

Section: Structure Of Lntrusionsmentioning

confidence: 78%

“…Some Fedorov [1976] has recently surveyed the considerable body of evidence which shows that a large intrusion (such as the Mediterranean outflow into the Atlantic) typically breaks up into a number of thinner layers, interleaving with the surrounding water. These produce local inversions of temperature, but the density structure remains stable in the vertical [Pingree, 1972;Howe and Tait, 1972]. This of course implies that there is a compensating salinity increase associated with each warm intrusion and already suggests that double-diffusive effects could be important.…”

Section: Comparison With Ocean Observationsmentioning

confidence: 99%

“…Note, how-ever, that even these layers, with sharp interfaces above and below in which fingers have been observed directly [A. J. Williams, 1975], sometimes have weak reversed gradients of T and S through the interior [Howe and Tait, 1970]. This has previously been attributed to incomplete mixing of the convective elements [Stern and Turner, 1969], but it is the distribution which would be produced by horizontal advection, maintained by horizontal property gradients (cf.…”

Section: Spatial Variationsmentioning

confidence: 99%

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Double‐diffusive intrusions into a density gradient

Turner¹

1978

J. Geophys. Res.

110

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It is now accepted that double‐diffusive processes play a part in the mixing of heat and salt in the ocean and that relevant information about them can be obtained from laboratory experiments. There is still a considerable gap, however, between the laboratory work and the conditions under which the phenomena occur in the ocean. Most of the laboratory experiments have been one dimensional, whereas in the ocean, strong double‐diffusive layering is often associated with large horizontal gradients of T and S, especially where water with one set of T‐S properties intrudes at its own density level into an environment with different properties. The main purpose of the present paper is to report a series of laboratory experiments which are related to the latter case. The sugar‐salt system and shadowgraph photography have been used to explore various situations of increasing complexity. The double‐diffusive effects are compared with the behavior of a simple source of salt solution, which intrudes horizontally as a thin layer into a salinity gradient at its own density level. In strong contrast to this a source of sugar in the same salinity gradient produces vigorous vertical convection near the source, followed by spreading at several levels. The extending fluid moves out at an angle to the horizontal, rising or falling across isopycnals in a manner which can be related to the composition of the environment and source fluids and the double‐diffusive transports across the boundaries of the intrusions. When the ambient fluid is set up with opposing gradients, so that potential energy is stored in one of the components, there is a more rapid spreading both horizontally and vertically, and strong shears are produced. The laboratory results are compared with published oceanic data to suggest explanations of some existing observations and to predict what might be measurable in future work.

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Section: Structure Of Lntrusionsmentioning

confidence: 78%

Section: Comparison With Ocean Observationsmentioning

confidence: 99%

Section: Spatial Variationsmentioning

confidence: 99%

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Double‐diffusive intrusions into a density gradient

Turner¹

1978

J. Geophys. Res.

110

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“…In the Gulf of Cadiz, the outflow, forming an undercurrent, splits into two major branches, mainly guided by the topography: a warmer, less saline upper core around 800 m (Mu) and a colder, more saline lower one (M1) around 1200 m (ZENK, 1970;AMBAR and HOWE, 1979;RHEIN and HINRICHSEN, 1993). This structure can be traced into the open ocean (Howe and TAIT, 1972;SIEDLER and ZENK, 1973). The hydrographic and tracer signal of the MWoutflow through the Straits of Gibraltar is considerably altered in the Gulf of Cadiz, and entrainment of Atlantic water from shallow horizons affects the upper core, Mu, more than MI (RHEIN and HINRICHSEN, 1993).…”

Section: Introductionmentioning

confidence: 99%

On the origin and the spreading of the shallow Mediterranean water core in the Iberian basin

Hinrichsen

Rhein

1993

Deep Sea Research Part I: Oceanographic Research Papers

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The origin and the spreading of the shallow Mediterranean water core (Ms) in the Iberian basin is discussed with a quasi-synoptic hydrographic data set enhanced by chlorofluoromethane (CFM) measurements. Its characteristic density level is found to be q = 27.4. Characterized by high temperature and CFM values, Ms enters the Iberian basin in the region of Cape St Vincent between depths of 500-750 dbar. A heat anomaly of >11.8 x 109 J m-2 is chosen as the boundary between the presence of Ms and the background field. The core is found in a tongue-like shape as well as in separate isolated eddies of both cyclonic and anticyclonic circulation. Using the optimum multiparameter analysis (TOMCZAK and LARGE, 1989, Journal of Geophysical Research, 94, 16141-16149), the North Atlantic Central Water (NACW), which mixes with the Mediterranean outflow to form Ms, turned out to be in the mean I°C warmer and 0.11 saltier than in regions with minor Mediterranean influence. This points to the Gulf of Cadiz as the origin of Ms, where the Mediterranean outflow is in contact with NACW of the appropriate characteristic.

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“…were given at the recent Chapman Conference on Oceanic Fronts [1977]. Other examples illustrating fine structure with temperature excursions exceeding 1 øC have been reported by Gregg [1975] in the California Current and by Howe and Tait [1972] in the Mediterranean outflow.…”

Section: Introductionmentioning

confidence: 99%

Temperature fine structure near the Sea‐ice margin of the Chukchi Sea

Paquette¹,

Bourke²

1979

J. Geophys. Res.

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Temperature fine structure with peak‐to‐peak fluctuations often exceeding 2°C is prevalent throughout the marginal sea‐ice zone of the shallow Chukchi Sea in midsummer. It is normally found within 20–35 km outside of the ice and seldom farther than 5–10 km inside the ice margin. It has also been infrequently found more than 100 km south of the ice. Temperature and salinity fronts of all degrees of sharpness occur in the same general area, but the two types need not be coincident. Considerable variability in time and length scales of fine structure elements has been noted with persistences ranging from 2 hours or less to more than 20 hours and length scales ranging from 600 m to more than 20 km. While much of this variability is intrinsic, part can be accounted for by the inability to sample in the direction of flow and the relative motion between the sampling platform and fine structure element. Fine structure lenses are considerably longer parallel to the ice edge with similarity in temperature structure noted over distances of 80 and 100 km.

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The role of temperature inversions in the mixing processes of the deep ocean

Cited by 5 publications

References 13 publications

Double‐diffusive intrusions into a density gradient

Double‐diffusive intrusions into a density gradient

On the origin and the spreading of the shallow Mediterranean water core in the Iberian basin

Temperature fine structure near the Sea‐ice margin of the Chukchi Sea

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