Thermohaline intrusions in the frontal zones of a warm‐core ring observed by Batfish

Tang, Choon Yik; Bennett, A. J.; Lawrence, D.E.

doi:10.1029/jc090ic05p08928

Cited by 24 publications

(9 citation statements)

References 16 publications

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“…The model demonstrates that this subsurface transport of the shelf water occurs alongside of the surface‐visible (to satellites) shelf‐water streamer (Figure ). This is consistent with field observations sometimes showing subsurface shelf water adjacent to surface‐visible shelf‐water streamers on the periphery of WCRs (e.g., Kupferman & Garfield, ; Tang et al, ). From the prospective of someone who analyzes satellite remote‐sensing data, the subsurface offshore transport of the subducted shelf water thus behaves as a surface‐invisible part of the streamer transport.…”

Section: Discussionsupporting

confidence: 90%

“…The WCR‐induced cross‐shelfbreak offshore transport of the shelf water can also occur below the sea surface. Observations have shown subsurface fluxes of shelf water on the ring periphery alongside of surface‐visible shelf‐water streamers (e.g., Churchill et al, ; Kupferman & Garfield, ; Tang et al, ). The model of Cherian and Brink () produces a type of subsurface offshore flux of the shelf‐slope water, and they attribute it to the along‐isopycnal sinking of the shelf‐slope water.…”

Section: Introductionmentioning

confidence: 99%

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Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring

Zhang

Partida

2018

JGR Oceans

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This work studies the subduction of the shelf water along the onshore edge of a warm‐core ring that impinges on the edge of the Mid‐Atlantic Bight continental shelf. The dynamical analysis is based on observations by satellites and from the Ocean Observatories Initiative Pioneer Array observatory as well as idealized numerical model simulations. They together show that frontogenesis‐induced submesoscale frontal subduction with order‐one Rossby and Froude numbers occurs on the onshore edge of the ring. The subduction flow results from the onshore migration of the warm‐core ring that intensifies the density front on the interface of the ring and shelf waters. The subduction is a part of the cross‐front secondary circulation trying to relax the intensifying density front. The dramatically different physical and biogeochemical properties of the ring and shelf waters provide a great opportunity to visualize the subduction phenomenon. Entrained by the ring‐edge current, the subducted shelf water is subsequently transported offshore below a surface layer of ring water and alongside of the surface‐visible shelf‐water streamer. It explains the historical observations of isolated subsurface packets of shelf water along the ring periphery in the slope sea. Model‐based estimate suggests that this type of subduction‐associated subsurface cross‐shelfbreak transport of the shelf water could be substantial relative to other major forms of shelfbreak water exchange. This study also proposes that outward spreading of the ring‐edge front by the frontal subduction may facilitate entrainment of the shelf water by the ring‐edge current and enhances the shelf‐water streamer transport at the shelf edge.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring

Zhang

Partida

2018

JGR Oceans

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“…Since the shelf water is generally denser than ambient slope water, the densest shelf water in the filament will appear as a subsurface core in observational cross sections. Observations of subsurface cores of 32 psu, 108C water, typical of near-bottom cold pool shelf water (Houghton et al 1982), are common (e.g., Nelson et al 1985;Tang et al 1985;Ramp et al 1983;Garfield and Evans 1987). These cores are outside the eddy.…”

Section: B Observational Evidencementioning

confidence: 99%

Offshore Transport of Shelf Water by Deep-Ocean Eddies

Cherian

Brink

2016

Journal of Physical Oceanography

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At continental margins, energetic deep-ocean eddies can transport shelf water offshore in filaments that wrap around the eddy. One example is that of Gulf Stream warm-core rings interacting with the Mid-Atlantic Bight shelf. The rate at which shelf water is exported in these filaments is a major unknown in regional budgets of volume, heat, and salt. This unknown transport is constrained using a series of idealized primitive equation numerical experiments wherein a surface-intensified anticyclonic eddy interacts with idealized shelf-slope topography. There is no shelfbreak front in these experiments, and shelf water is tracked using a passive tracer. When anticyclones interact with shelf-slope topography, they suffer apparent intrusions of shelf-slope water, resulting in a subsurface maximum in offshore transport. The simulations help construct an approximate model for the filament of exported water that originates inshore of any given isobath. This model is then used to derive an expression for the total volume of shelf-slope water transported by the eddy across that isobath. The transport scales with water depth, radius, and azimuthal velocity scale of the eddy. The resulting expression can be used with satellite-derived eddy properties to estimate approximate real-world transports ignoring the presence of a shelfbreak front. The expression assumes that the eddy's edge is at the shelf break, a condition not always satisfied by real eddies.

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“…Unlike mesoscale turbulence, submesoscale flow is essentially three-dimensional, so the vertical velocities associated with these features may be strong enough to have a local effect on both lateral and vertical fluxes of heat, salt, nutrients, and other tracers Thomas et al 2008). Indirect evidence of vertically sheared submesoscale exchange is occasionally observed as intrusions or interleaving at the edges of mesoscale features (Tang et al 1985;Schmitt et al 1986;Armi et al 1989;Hitchcock et al 1994). It is a compelling possibility that such interleaving is the three-dimensional expression of submesoscale turbulence, conceptually similar to the complex structure of streaks and filaments revealed by surface observations.…”

Section: A Background and Motivationmentioning

confidence: 99%

Three-Dimensional Structure and Temporal Evolution of Submesoscale Thermohaline Intrusions in the North Pacific Subtropical Frontal Zone

Shcherbina

Gregg

Alford

et al. 2010

Journal of Physical Oceanography

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Four instances of persistent intrusive deformation of the North Pacific Subtropical Front were tagged individually by a Lagrangian float and tracked for several days. Each feature was mapped in three dimensions using repeat towed observations referenced to the float. Isohaline surface deformations in the frontal zone included sheetlike folds elongated in the alongfront direction and narrow tongues extending across the front. All deformations appeared as protrusions of relatively cold, and fresh, water across the front. No corresponding features of the opposite sign or isolated lenslike structures were observed. The sheets were O(10 m) thick, protruded about 10 km into the warm saline side of the front, and were coherent for 10-30 km along the front. Having about the same thickness and cross-frontal extent as the sheets, tongues extended less than 5 km along the front. All of the intrusions persisted as long as they were followed, several days to one week. Their structures evolved on both inertial (23 h) and subinertial (;10 days) time scales in response to differential lateral advection. The water mass surrounding the intrusions participated in gradual anticyclonic rotation as a part of a mesoscale meander of the subtropical front. The intrusions may be interpreted as a manifestation of three-dimensional submesoscale turbulence of the frontal zone, driven by the mesoscale. Absence of large features of the opposite sign may be indicative of the asymmetry of the underlying dynamics.

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Thermohaline intrusions in the frontal zones of a warm‐core ring observed by Batfish

Cited by 24 publications

References 16 publications

Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring

Frontal Subduction of the Mid‐Atlantic Bight Shelf Water at the Onshore Edge of a Warm‐Core Ring

Offshore Transport of Shelf Water by Deep-Ocean Eddies

Three-Dimensional Structure and Temporal Evolution of Submesoscale Thermohaline Intrusions in the North Pacific Subtropical Frontal Zone

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