Evolution of a Mediterranean Salt Lens: Scalar Properties

Hebert, Dave; Oakey, Neil S.; Ruddick, Barry

doi:10.1175/1520-0485(1990)020<1468:eoamsl>2.0.co;2

Cited by 92 publications

(84 citation statements)

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“…Our eddy translations are consistent with that larger-scale middepth gyre circulation pattern. The Rossby number Ro is defined as Ro 5 jV max j/ (R max f ) (see Hebert et al 1990). There are a few choices for the horizontal scale and velocity maximum that can be used in the calculation of Ro; here, the variables R max at V max are used because they represent the dynamic variables associated with eddy velocities.…”

Section: B Resultsmentioning

confidence: 99%

Observations of Irminger Sea Anticyclonic Eddies

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Journal of Physical Oceanography

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Section: B Resultsmentioning

confidence: 99%

Observations of Irminger Sea Anticyclonic Eddies

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et al. 2013

Journal of Physical Oceanography

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“…It is more difficult to reliably assess a decrease of the meddy radius with time (if any), since the RAFOS' positions relative to the meddy centre may be a result of their migration within the meddy. Repeated observations of meddy Sharon (Hebert et al, 1990) showed that its dynamical radius decreased by 9 km during a year of observations. To compute the time evolution of the meddy surface signatures in Fig.…”

Section: Analysis Of Meddy Surface Signals In the Northeastern Atlantmentioning

confidence: 94%

“…Such small meddies should quickly loose their surface signatures if they take a southern path, e.g. along the coast of Africa (Hebert et al, 1990). Meddies with R m = 30 km with either shallow or deep cores are detectable in both subtropics and northern tropics, at least as far as [25][26][27][28][29][30] • N. This latter prediction corresponds well to the evolution of the surface signal of meddy Hyperion, which became weak and often intermittent south of 30 • N. Figure 8 also shows that the isolines of the sea surface elevation ζ in the Eastern North Atlantic are nearly zonal; therefore we can easily compute critical latitudes, south of which a meddy cannot be identified in altimetry, in the [H, R m ] plane (Fig.…”

Section: Analysis Of Meddy Surface Signals In the Northeastern Atlantmentioning

confidence: 99%

“…For meddies, horizontal intrusions are thought to be the most probable mechanism for heat and salt exchange across their lateral boundaries, but they are not an efficient mechanism for vorticity dissipation until the late stages of the eddy disintegration (Hebert, 1988;Hebert et al, 1990). Relative vorticity decay in meddies may be due to their interaction with a background shear flow, which strips vorticity away (Legras and Dritschel, 1993;Mariotti et al, 1994), or to energy dispersion through radiation of Rossby waves (Flierl, 1984).…”

Section: Introductionmentioning

confidence: 99%

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Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification

Bashmachnikov

Carton

2012

Ocean Sci.

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Abstract. Meddies, intra-thermocline eddies of Mediterranean water, can often be detected at the sea surface as positive sea-level anomalies. Here we study the surface signature of several meddies tracked with RAFOS floats and AVISO altimetry.While pushing its way through the water column, a meddy raises isopycnals above. As a consequence of potential vorticity conservation, negative relative vorticity is generated in the upper layer. During the initial period of meddy acceleration after meddy formation or after a stagnation stage, a cyclonic signal is also generated at the sea-surface, but mostly the anticyclonic surface signal follows the meddy.Based on geostrophy and potential vorticity balance, we present theoretical estimates of the intensity of the surface signature. It appears to be proportional to the meddy core radius and to the Coriolis parameter, and inversely proportional to the core depth and buoyancy frequency. This indicates that surface signature of a meddy may be strongly reduced by the upper ocean stratification. Using climatic distribution of the stratification intensity, we claim that the southernmost limit for detection in altimetry of small meddies (with radii on the order of 10-15 km) should lie in the subtropics (35-45 • N), while large meddies (with radii of 25-30 km) could be detected as far south as the northern tropics (25-35 • N). Those results agree with observations.

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“…Meddy Sharon is a warm, salty lens of Mediterranean water that was observed in the eastern North Atlantic from 1984 to 1986 (Armi et al, 1989). During the period of observation, its heat, salt and velocity characteristics were gradually eroded away by lateral interleaving (Ruddick and Hebert, 1988;Hebert et al, 1990). The Meddy has been well-studied and evidence has been presented that the thermo-haline intrusions were double-diffusively driven (Ruddick, 1992).…”

Section: Introductionmentioning

confidence: 99%

Contrasting the interleaving in two baroclinic ocean fronts

May

Kelley

2002

Dynamics of Atmospheres and Oceans

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To investigate the effects of baroclinicity on frontal interleaving, we contrast the interleaving characteristics of two fronts, one in the Arctic Ocean and the other surrounding a Mediterranean salt lens (Meddy). The Meddy is broken into two parts based on the vertical temperature and salinity structure, so our comparison involves three sets of interleaving observations. The cross-front slopes of intrusions relative to horizontal and isopycnal surfaces are taken to be key diagnostics of the interleaving dynamics. Assuming the observed slopes match those that were present during the initial growth of interleaving, we use an instability theory to infer the dominant form of double diffusion that was active during the growth stage. Then, to investigate the observed interleaving, we use a steady-state model to infer the dominant form of double diffusion at the time of observation. In the Arctic Ocean front, it appears that different forms of double diffusion dominated the two stages of interleaving (salt fingering during the growth stage and diffusive convection at steady state). In contrast, in the Meddy, the same form of double diffusion appears to have dominated both stages of interleaving (salt fingering in the lower part of the Meddy, diffusive convection in the upper part). In the Arctic Ocean front, the observations suggest that interleaving was driven by baroclinicity as well as double diffusion. In both parts of the Meddy, however, driving was by double diffusion only. Motivated by these differences, we suggest a new intrusion classification scheme, based on the slopes of intrusions relative to horizontal and isopycnal surfaces.

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Evolution of a Mediterranean Salt Lens: Scalar Properties

Cited by 92 publications

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Observations of Irminger Sea Anticyclonic Eddies

Observations of Irminger Sea Anticyclonic Eddies

Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification

Contrasting the interleaving in two baroclinic ocean fronts

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