Evidence of Mediterranean Water dipole collision in the Gulf of Cadiz

L’Hégaret, Pierre; Carton, Xavier; Ambar, Isabel; Ménesguen, Claire; Hua, Bach Lien; Chérubin, Laurent M.; Aguiar, Ana Barbosa; Cann, Bernard Le; Daniault, Nathalie; Serra, Nuno

doi:10.1002/2014jc009972

Cited by 32 publications

(28 citation statements)

References 46 publications

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“…In fact, in some cases, a vortex may correspond to a zone depleted of buoyancy. Consequently, deep vortex detection from sea surface temperature (or sea surface density anomaly) alone is generally not reliable, see Carton et al (2010) andl'Hégaret et al (2014).…”

Section: Resultsmentioning

confidence: 99%

Interaction between a surface quasi-geostrophic buoyancy filament and an internal vortex

Reinaud

Dritschel

Carton

2016

Geophysical & Astrophysical Fluid Dynamics

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This paper focuses on the nonlinear interaction between a surface quasi-geostrophic buoyancy filament and an internal vortex. We first revisit the stability of an isolated buoyancy filament. The buoyancy profile considered is continuous and leads to a continuous velocity field, albeit one with infinite shear just outside its edge. The stability properties of an isolated filament help to interpret the unsteady interaction with a sub-surface (internal) vortex studied next. We find that, in all cases, the filament breaks into billows, analogous in form to those occurring in Kelvin-Helmholtz shear instability. For intense buoyancy filaments, the vortex itself may undergo strong deformations, including being split into several pieces. Generally, the nonlinear interaction causes both the filament and the vortex to lose their respective 'self'-energies to the energy of interaction. The flow evolution depends sensitively on whether the vertical vorticity of the filament and the vortex have the same or opposite signs -termed "cooperative" and "adverse" shear respectively. In cooperative shear, the filament rolls up into a coherent surface eddy above a vortex initially placed below it, whereas in adverse shear, buoyancy is expelled above the vortex. Although sufficiently great shear induced by the buoyancy filament may split the vortex in both cases, adverse shear is significantly more destructive.

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Section: Resultsmentioning

confidence: 99%

Interaction between a surface quasi-geostrophic buoyancy filament and an internal vortex

Reinaud

Dritschel

Carton

2016

Geophysical & Astrophysical Fluid Dynamics

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“…In the Western Arabian Sea, a large anticyclone, the Great Whirl, has been observed to merge with the nearby Socotra Eddy, along the Somali coast (Vic et al, 2014). Vortex merger in the ocean also occurs at depth: numerical simulations and in-situ observations have shown the merger of deep eddies of Mediterranean Water (meddies), near the Iberian continental shelf, in the Northeastern Atlantic ocean (Schultz-Tokos et al, 1994;Carton et al, 2010;Aguiar et al, 2013;L'Hegaret et al, 2014). Therefore vortex merger near a coast is a common process in the ocean.…”

Section: Introductionmentioning

confidence: 99%

Vortex merger near a topographic slope in a homogeneous rotating fluid

et al. 2017

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The effect of a bottom slope on the merger of two identical Rankine vortices is investigated in a two dimensional, quasi-geostrophic, incompressible fluid. When two cyclones initially lie parallel to the slope, and more than two vortex diameters away from the slope, the critical merger distance is unchanged. When the cyclones are closer to the slope, they can merge at larger distances, but they lose more mass 1 into filaments, thus weakening the efficiency of merger. Several effects account for this: the topographic Rossby wave advects the cyclones, reduces their mutual distance and deforms them. This alongshelf wave breaks into filaments and into secondary vortices which shear out the initial cyclones. The global motion of fluid towards the shallow domain and the erosion of the two cyclones are confirmed by the evolution of particles seeded both in the cyclones and near the topographic slope. The addition of tracer to the flow indicates that diffusion is ballistic at early times. For two anticyclones, merger is also facilitated because one vortex is ejected offshore towards the other, via coupling with a topographic cyclone. Again two anticyclones can merge at large distance but they are eroded in the process. Finally, for taller topographies, the critical merger distance is again increased and the topographic influence can scatter or completely erode one of the two initial cyclones. Conclusions are drawn on possible improvements of the model configuration for an application to the ocean.

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“…This occurs for instance for Gulf Stream rings, or for Mediterranean Water eddies near the Iberian coast L'Hegaret et al, 2014). These Mediterranean water eddies were shown to interact as a result of their advection by cyclonic partner vortices.…”

Section: Introductionmentioning

confidence: 97%

Vortex merger in surface quasi-geostrophy

Carton

Ciani

Verron

et al. 2015

Geophysical & Astrophysical Fluid Dynamics

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The merger of two identical surface temperature vortices is studied in the surface quasigeostrophic model. The motivation for this study is the observation of the merger of submesoscale vortices in the ocean. Firstly, the interaction between two point vortices, in the absence or in the presence of an external deformation field, is investigated. The rotation rate of the vortices, their stationary positions and the stability of these positions are determined. Then, a numerical model provides the steady states of two finite-area, constant-temperature, vortices. Such states are less deformed than their counterparts in two-dimensional incompressible flows. Finally, numerical simulations of the nonlinear surface quasi-geostrophic equations are used to investigate the finite-time evolution of initially identical and symmetric, constant temperature vortices. The critical merger distance is obtained and the deformation of the vortices before or after merger is determined. The addition of external deformation is shown to favor or to oppose merger depending on the orientation of the vortex pair with respect to the strain axes. An explanation for this observation is proposed. Conclusions are drawn towards an application of this study to oceanic vortices.2

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Evidence of Mediterranean Water dipole collision in the Gulf of Cadiz

Abstract: A collision of Mediterranean Water dipoles in the Gulf of Cadiz is studied here, using data from

Cited by 32 publications

References 46 publications

Interaction between a surface quasi-geostrophic buoyancy filament and an internal vortex

Interaction between a surface quasi-geostrophic buoyancy filament and an internal vortex

Vortex merger near a topographic slope in a homogeneous rotating fluid

Vortex merger in surface quasi-geostrophy

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