Dynamics of ventilated coherent cold eddies on a sloping bottom

Swaters, Gordon E.; Flierl, Glenn R.

doi:10.1017/s0022112091001556

Cited by 44 publications

(64 citation statements)

References 23 publications

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“…Similar eddy-slope interaction processes have been studied by Wang (1992) and (Sutyrin et al, 2003). The eddy-slope interaction can lead to strong wave dispersion, in which the shelf-ring interaction can generate topographic RWs (Swaters and Flierl, 1991;Sutyrin et al, 2003). Planetary and topographic β-effects are important for a deep reaching, mesoscale, eddy structure.…”

Section: Discussionsupporting

confidence: 56%

“…Further studies are required to trace the water properties in such large eddy-slope generated cyclonic eddies. Swaters and Flierl (1991) analyzed the internal structure and interaction characteristics of cold-core eddies on a sloping bottom and found a correlation between decay of the translation speed and the process of ventilation, which stimulated topographic Rossby waves. Cyclonic eddies can aid in the advection of Agulhas eddies out of the Cape Basin (Baker-Yeboah, 2008) and are important in the evolution of Agulhas rings, as these eddies translate and mix into the the basin scale ocean circulation.…”

Section: Discussionmentioning

confidence: 99%

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Transformation of an Agulhas eddy near the continental slope

et al. 2010

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Abstract. The transformation of Agulhas eddies near the continental slope of southern Africa and their subsequent self-propagation are analyzed in both observational data and numerical simulations. Self-propagation results from a net dipole moment of a generalized heton structure consisting of a surface-intensified anticyclonic eddy and deep cyclonic pattern. Such Agulhas vortical structures can form near the retroflection region and further north along the western coast of southern Africa. We analyze nonlinear topographic wave generation, vortex deformations, and filament production as an important part in water mass exchange. Self-propagating structures provide a conduit for exchange between the deep ocean and shelf regions in the Benguela upwelling system.

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Section: Discussionsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Transformation of an Agulhas eddy near the continental slope

et al. 2010

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“…Similarly, a northward drift was predicted by Swaters & Flierl (1991) to occur as a result of mixing ('ventilation') of the dense eddy with the surrounding ambient.…”

Section: Introductionmentioning

confidence: 88%

Rotating dense currents on a slope. Part 1. Stability

et al. 2004

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Using a novel experimental set-up, we examine the stability of an axisymmetric dense current of fluid on a sloping bottom in a rotating frame of reference. In a cylindrical tank on a rotating table, saline fluid is injected through an annular mesh encircling a cone of 1/15 slope. The resulting ring of fluid becomes unstable to periodic sinusoidal waves, whose characteristics are examined as a function of the ambient fluid depth, the rotation rate, and the salinity and depth of the dense current, the latter being related to the injection time. For experiments with relatively low-salinity currents, we find the phase speed of the instability is proportional to the rotation rate, Ω, rather than being proportional to the Nof speed, which varies as 1/Ω. Likewise, the number of waves observed is found to be inconsistent with existing theories for baroclinic instability of a dense current on a sloping bottom with a stationary ambient.Surface tracers reveal that significant currents are induced in the ambient by the injection of the saline fluid and we propose that it is the coupling between the surface and bottom flow that ultimately controls the observed dynamics. In particular, we propose that barotropic instability of the surface flow controls the behaviour of the low-salinity current and, using potential vorticity conservation, we predict the phase speed of the instability should indeed be proportional to Ω. The experimental results are also compared with related work in which eddies and Ekman layers evolve from dense fluid injected from a localized source.

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“…A number of subsequent studies (e.g. Jungclaus et al (2001) who make a comparison to atmospheric frontal cyclogenesis and Swaters and Flierl (1991)) have added details building on the notion of baroclinic instability being responsible for the formation of DSOW eddies.…”

Section: Dsow Eddies and Cyclogenesis Mechanismsmentioning

confidence: 99%

Moored observations of shelfbreak processes at the inflow to and outflow from the Arctic Ocean

Appen¹

2013

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Two high-resolution mooring arrays extending from the outer shelf to the mid continental slope are used to elucidate shelf-basin exchange at the inflow to and the outflow from the Arctic Ocean. Pacific Water entering the Arctic Ocean forms the Western Arctic shelfbreak current along the Beaufort Sea slope. Data from the mooring array at 152• W-approximately 150 km east of Pt. Barrow, AK-reveals that this current has two distinct states in summer depending on the water mass it transports. When advecting Alaskan Coastal Water it is surface-intensified and both baroclinically and barotropically unstable. This configuration lasts about a month with an average transport of 0.7 Sv. When advecting Chukchi Summer Water the current is bottom-intensified and is only baroclinically unstable. This state also exists for approximately a month with an average transport of 0.6 Sv. The strong mean-toeddy energy conversion causes both configurations of the current to spin down over a distance of a few hundred kilometers, suggesting that warm Pacific Water does not enter the Canadian Arctic Archipelago via this route.Dense water formed in the Nordic Seas overflows the Denmark Strait and undergoes vortex stretching, forming intense cyclones that propagate along the East Greenland slope. Data from the mooring array at 65• N-roughly 300 km downstream of Denmark Strait-was used to determine the full water column structure of the cyclones. On average a cyclone passes the array every other day in the vicinity of the 900 m isobath, although the depth range of individual cyclones ranges between the 500 m and 1600 m isobaths. The cyclones self-propagate at 0.45 m/s and are also advected by the mean flow of 0.27 m/s, resulting in a total propagation speed of 0.72 m/s. They have a peak azimuthal speed of 0.22 m/s at a radius of 7.8 km and contain overflow water in their core. In the absence of the cyclones, the background This work would not have been possible without the diligent efforts of many people in collecting and processing the data. We thank the crews of the R/V Árni Friðriksson

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Dynamics of ventilated coherent cold eddies on a sloping bottom

Cited by 44 publications

References 23 publications

Transformation of an Agulhas eddy near the continental slope

Transformation of an Agulhas eddy near the continental slope

Rotating dense currents on a slope. Part 1. Stability

Moored observations of shelfbreak processes at the inflow to and outflow from the Arctic Ocean

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