|
|
|
| Registros recuperados: 77 | |
|
|
| De Marez, Charly; Carton, Xavier; Morvan, Mathieu; Reinaud, Jean N.. |
| We study the influence of bottom topography on the interaction of two identical vortices in a two-layer, quasi-geostrophic model. The two vortices have piecewise-uniform potential vorticity and are lying in the upper layer of the model. The topography is a smooth bottom slope. For two cyclones, topography modifies the merger critical distance and the merger efficiency: the topographic wave and vortices can advect the two cyclones along the shelf when they are initially far from it or towards the shelf when they are initially closer to it. They can also advect the two cyclones towards each other and thus favour merger. The cyclones deform, and the potential vorticity field undergoes filamentation. Regimes of partial vortex merger or of vortex splitting are... |
| Tipo: Text |
Palavras-chave: Vortex interaction; Topography; Quasi-geostrophic model. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00600/71250/69625.pdf |
| |
|
|
| Géli, Louis; Savoye, Bruno; Carton, Xavier; Stephan, Manuel. |
| Reflection seismics has been intensively used for the last four decades by marine geologists and geophysicists for imaging Earth structures below the seafloor. Because their subject of interest is below the sea bottom, solid Earth scientists do not usually consider the seismic signal propagating in the water column and most often do not even record it, in order to save data storage space. Two physical oceanographers, Gonella and Michon [1988],first reported internal waves revealed by reflection seismics in the northeastern Atlantic. Only recently, though, has the scientific community realized the importance of this issue, after Holbrook et al. [2003] published reflection seismic sections of the water column off Newfoundland, Canada, showing reflectors... |
| Tipo: Text |
|
| Ano: 2005 |
URL: http://archimer.ifremer.fr/doc/00451/56259/57828.pdf |
| |
|
|
| Reinaud, J. N.; Dritschel, D. G.; Carton, Xavier. |
| This paper addresses the dynamical coupling of the ocean's surface and the ocean's interior. In particular, we investigate the dynamics of an oceanic surface jet and its interaction with vortices at depth. The jet is induced by buoyancy (density) anomalies at the surface. We first focus on the jet alone. The linear stability indicates there are two modes of instability: the sinuous and the varicose modes. When a vortex in present below the jet, it interacts with it. The velocity field induced by the vortex perturbs the jet and triggers its destabilisation. The jet also influences the vortex by pushing it under a region of co-operative shear. Strong jets may also partially shear out the vortex. We also investigate the interaction between a surface jet and a... |
| Tipo: Text |
|
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00600/71255/69633.pdf |
| |
|
|
| Barbosa Aguiar, A. C.; Menesguen, Claire; Le Gentil, Sylvie; Schopp, Richard; Carton, Xavier. |
| Nearly all the subsurface eddies detected in seismic imaging of sections in the northeast Atlantic have been assumed to be anticyclones containing Mediterranean Water (MW). Fewer MW cyclones have been observed and studied. In this study, the work of previous numerical studies is extended to investigate some characteristics of layering surrounding MW cyclones, using a primitive equation model with equal diffusivities for salinity and temperature to suppress the effects of double diffusion. It is shown that, after a stable state is reached, both anticyclones and cyclones display similar patterns of layering: stacked thin layers of high acoustic reflectivity located above and below the core of each vortex, which do not match isopycnals. The authors conclude... |
| Tipo: Text |
Palavras-chave: Geographic location/entity; North Atlantic Ocean; Circulation/ Dynamics; Small scale processes; Atm/Ocean Structure/ Phenomena; Eddies; Vortices; Observational techniques and algorithms; Acoustic measurements/effects; Models and modeling; Primitive equations model. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00281/39190/37746.pdf |
| |
|
|
| Bashmachnikov, I.; Carton, Xavier; Belonenko, T. V.. |
| In this work, we obtain new results on the manifestation of meddies (or of other deep eddies) at the sea-surface, further developing the results by Bashmachnikov and Carton (2012). The quasi-geostrophic equations are used to describe a near-axisymmetric vortex in the upper ocean, forced at its lower boundary by the isopycnal elevation of a moving meddy. The solution thus obtained provides a better approximation of the characteristics of meddy surface signals. The results show that in subtropics large meddies with dynamic radius R-m >30 km are always seen at the sea-surface with AVISO altimetry, that medium-size meddies with R-m = 20 km may be seen at the sea-surface only if they are sufficiently shallow and strong, while small meddies with R-m =10 km... |
| Tipo: Text |
Palavras-chave: Meddies; Surface signal; Altimetry. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00245/35615/34134.pdf |
| |
|
| |
|
|
| Morvan, Mathieu; L'Hégaret, Pierre; Carton, Xavier; Gula, Jonathan; Vic, Clement; Sokolovskiy, Mikhail; Koshel, Konstantin. |
| The Persian Gulf Water and Red Sea Water are salty and dense waters recirculating at subsurface in the Gulf of Oman and the Gulf of Aden respectively, under the influence of mesoscale eddies which dominate the surface flow in both semi-enclosed basins. In situ measurements combined with altimetry indicate that the Persian Gulf Water is driven by mesoscale eddies in the form of filaments and submesoscale structures. In this paper, we study the formation and the life cycle of intense submesoscale vortices and their impact on the spread of Persian Gulf Water and Red Sea Water. We use a three-dimensional hydrostatic model with submesoscale-resolving resolution to study the evolution of submesoscale vortices. Our configuration is an idealized version of the... |
| Tipo: Text |
|
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70153/68140.pdf |
| |
|
|
| Cassianides, Angelina; Martinez, Elodie; Maes, Christophe; Carton, Xavier; Gorgues, Thomas. |
| The Marquesas islands are a place of strong phytoplanktonic enhancement, whose original mechanisms have not been explained yet. Several mechanisms such as current−bathymetry interactions or island run-off can fertilize waters in the immediate vicinity or downstream of the islands, allowing phytoplankton enhancement. Here, we took the opportunity of an oceanographic cruise carried out at the end of 2018, to combine in situ and satellite observations to investigate two phytoplanktonic blooms occurring north and south of the archipelago. First, Lagrangian diagnostics show that both chlorophyll-a concentrations (Chl) plumes are advected from the islands. Second, the use of Finite-size Lyaponov Exponent and frontogenesis diagnostics reveal how the Chl plumes... |
| Tipo: Text |
Palavras-chave: Mesoscale dynamics; Chlorophyll-a concentration variability; Coastal fertilization; Horizontal advection; Marquesas islands. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00649/76115/77077.pdf |
| |
|
|
| Sutyrin, G; Perrot, Xavier; Carton, Xavier. |
| The evolution of a self-propelling vortex dipole, embedded in an external nondivergent flow with constant potential vorticity, is Studied in an equivalent-barotropic model commonly used in geophysical, astrophysical and plasma studies. In addition to the conservation of the Hamiltonian for an arbitrary point vortex dipole, it is found that the angular momentum is also conserved when the external flow is axisymmetric. This reduces the original four degrees of freedom to only two, so that the solution is expressed in quadratures. In particular, the scattering of antisymmetric dipoles approaching from the infinity is analyzed in the presence of an axisymmetric oceanic flow typical for the vicinity of isolated seamounts. |
| Tipo: Text |
Palavras-chave: Quasi geostrophic; Topography interaction; Rotating fluids; Vortex dynamics. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-7320.pdf |
| |
|
|
| Pous, Stephane; Carton, Xavier; Lazure, Pascal. |
| A shallow-water model, coupled with a three dimensional, hydrostatic ocean model, is used to study the wind induced circulation, and the Shatt-al-Arab river plume expansion, in the Persian Gulf. The models are used in an idealized configuration. The following results are obtained: 1) with northwesterly winds, a double gyre is formed: this gyre is cyclonic in the south and anticyclonic in the north. Southeastward currents flow along the Iranian and Arabian coast where the wind stress at the surface dominates the pressure gradient related to the free surface slope, and conversely in the deeper region of the Gulf; 2) In the eastern part of the Gulf, the cyclonic gyre intensifies, as observed and reported in the literature; 3) For northwesterly winds, the... |
| Tipo: Text |
Palavras-chave: Persian Gulf; Wind-Induced Circulation; Hydrodynamical Modeling. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00284/39521/38014.pdf |
| |
|
|
| Buckingham, Christian; Gula, Jonathan; Carton, Xavier. |
| In this study, we examine the role of curvature in modifying frontal stability. We first evaluate the classical criterion that the Coriolis parameter f multiplied by the Ertel potential vorticity (PV) q is positive for stable flow and that instability is possible when this quantity is negative. The first portion of this statement can be deduced from Ertel’s PV theorem, assuming an initially positive fq. Moreover, the full statement is implicit in the governing equation for the mean geostrophic flow, as the discriminant, fq, changes sign. However, for curved fronts in cyclogeostrophic or gradient wind balance (GWB), an additional term enters the discriminant owing to conservation of absolute angular momentum L. The resulting expression, (1 + Cu)fq < 0 or... |
| Tipo: Text |
Palavras-chave: Instability; Ocean dynamics; Potential vorticity; Turbulence; Frontogenesis/frontolysis; Fronts; Vortices; Angular momentum. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00677/78920/81288.pdf |
| |
|
|
| Vandermeirsch, Frederic; Carton, Xavier; Morel, Yves. |
| The interaction between a stable zonal jet and a vortex is studied numerically with two one-and-a-half layer models, one with quasi-geostrophic dynamics, the other with shallow-water equations. In both models, simulations on the f-plane evidence three regimes occuring with increasing vortex strength: (regime 1) weak vortices do not cross the jet and steadily drift along it; (regime 2) stronger vortices cross the jet, tear an opposite-sign meander from the jet with which they pair as a dipole; the trajectory of this dipole depends on the strength of the initial vortex; since most dipoles are asymmetric, they veer back towards the jet axis where they are split apart in the ambient shear; (regime 3) even stronger vortices cross the jet and tear a vorticity... |
| Tipo: Text |
Palavras-chave: Potential vorticity; Vortices; Jets; Nonlinear equations; Stratified flow; Rotating fluids. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-440.pdf |
| |
|
|
| Ayouche, Adam; De Marez, Charly; Morvan, Mathieu; L'Hegaret, Pierre; Carton, Xavier; Le Vu, Briac; Stegner, Alexandre. |
| The Ras al Hadd oceanic dipole is a recurrent association of a cyclone (to the northeast) and of an anticyclone (to the southwest), which forms in summer and breaks up at the end of autumn. It lies near the Ras al Hadd cape, southeast of the Arabian peninsula. Its size is on the order of 100 km. Along the axis of this dipole flows an intense jet, the Ras al Had jet. Using altimetric data and an eddy detection and tracking algorithm (AMEDA: Angular Momentum Eddy Detection and tracking Algorithm), we describe the life cycle of this oceanic dipole over a year (2014–2015). We also use the results of a numerical model (HYCOM, the HYbrid Coordinate Ocean Model) simulation, and hydrological data from ARGO profilers, to characterize the vertical structure of the... |
| Tipo: Text |
Palavras-chave: Ras al hadd oceanic dipole; Arabian sea; Cyclonic and anticyclonic eddies; Altimetric data; Angular momentum eddy detection and tracking algorithm (AMEDA); HYCOM model; ARGO floats. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00679/79107/81598.pdf |
| |
|
|
| Meunier, Thomas; Sheinbaum, Julio; Pallàs Sanz, Enric; Tenreiro, Miguel; Ochoa, José; Angulo, Angel Ruiz; Carton, Xavier; Marez, Charly. |
| In this study, we harness the 25‐year satellite‐altimeter record, in concert with a vast array of in‐situ measurements, to estimate the heat content anomaly of 32 warm‐core rings in the Gulf of Mexico (GoM). The decay rate of these mesoscale eddies is studied in detail, and it is shown that they release the majority of their heat as they drift in the central GoM (away from topographic obstacles). The surface heat fluxes from the eddies is shown to be small in comparison to the total rate of heat loss from the eddies, suggesting that heat is primarily released towards the surrounding watermasses. Integrating the total heat evolution equation over the warm‐core rings yields an estimate of their effective lateral diffusivity coefficient. The long term impact... |
| Tipo: Text |
|
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00606/71769/70249.pdf |
| |
|
|
| Vandermeirsch, Frederic; Carton, Xavier; Morel, Yves. |
| In a two-and-a-half-layer quasi-geostrophic model, a process study is conducted on the interaction between a vortex and a zonal jet, both with constant potential vorticity. The vortex is a stable anticyclone, initially located north of the eastward jet. The potential vorticity of the jet is allowed to have various vertical structures, while the vortex is concentrated in only one layer. The flow parameters are set to values characteristic of the Azores region. First, the jet is stable. Weak vortices steadily drift north of the jet without crossing it while strong vortices can cross the jet and tear off a cyclone with which they pair as a heton (baroclinic dipole). This heton often breaks later in the shear exerted by the jet; the two vortices finally... |
| Tipo: Text |
Palavras-chave: Potential vorticity; Vortices; Jets; Nonlinear equations; Stratified flow; Rotating fluids. |
| Ano: 2003 |
URL: http://archimer.ifremer.fr/doc/2003/publication-441.pdf |
| |
|
|
| Ryzhov, Eugene A.; Koshel, Konstantin V.; Sokolovskiy, Mikhail A.; Carton, Xavier. |
| A simple dynamical model of vortex interactions taking place near a curved boundary mimicking a circular bay is formulated and examined. An initial configuration consisting of a point vortex in the bay and of an incident point vortex moving toward the bay along the straight part of the boundary is considered. Both vortices are of equal strengths. Typical stationary regimes of the bay-bound vortex when the incident vortex is far from the bay are obtained. When the incident vortex comes near the bay, its interaction with the bay-bound one may result in irregular motion of both vortices. Typical outcomes of the interaction are established to be (i) the incident vortex passes over the bay without forcing the bay-bound vortex to leave the bay; (ii) the incident... |
| Tipo: Text |
|
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00600/71249/69624.pdf |
| |
|
|
| L'Hegaret, P.; Duarte, R.; Carton, Xavier; Vic, Clement; Ciani, Daniele; Baraille, R.; Correard, S.. |
| The Arabian Sea and Sea of Oman circulation and water masses, subject to monsoon forcing, reveal a strong seasonal variability and intense mesoscale features. We describe and analyze this variability and these features, using both meteorological data (from ECMWF reanalyses), in situ observations (from the ARGO float program and the GDEM - Generalized Digital Environmental mode - climatology), satellite altimetry (from AVISO) and a regional simulation with a primitive equation model (HYCOM - the Hybrid Coordinate Ocean Model). The model and observations display comparable variability, and the model is then used to analyze the three-dimensional structure of eddies and water masses with higher temporal and spatial resolutions than the available observations.... |
| Tipo: Text |
|
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00286/39690/38149.pdf |
| |
|
| |
|
|
| Barbosa Aguiar, Ana Claudia; Peliz, Alvaro; Carton, Xavier. |
| The output from a high-resolution two-decade long Mediterranean Outflow simulation is analysed here to provide a census of Mediterranean Water eddies (aka Meddies), both anticyclones and cyclones. The formation rate of Meddies that survive for at least 90 days is of 12 Meddies yr(-1) of which similar to 12% are cyclones. The rate of formation reaches 40 Meddies yr(-1) (30% cyclones) when considering all the Meddies living over 15 days. About 70% of the population is born along the southwestern Iberian slope, but several robust Meddles also originate in points of convergence of the main pathways into the open ocean. The longest-lived Meddies propagate northwestwards, but most of the anticyclones veer southwestwards after a while. As the Meddies drift away... |
| Tipo: Text |
|
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00159/27073/25474.pdf |
| |
|
|
| Flierl, Glenn R.; Carton, Xavier; Messager, Chistophe. |
| In a two-layer quasi-geostrophic model, we investigate the mixed barotropic-baroclinic instability of a thin zonal jet. Given the jet velocity profile at the surface, the deformation radius and layer depths, the three parameters governing the instability are the ratio of layerwise maximum velocities (U2/U1), the planetary vorticity gradient (Beta-effect), and the wavenumber (k) of the perturbation. First, simple criteria provide thresholds in this parameter space for the onset of instability. Growth rates of monochromatic perturbations are then computed and their most unstable wavelengths are compared with oceanic observations. With a nonlinear numerical model, high-Reynolds-number evolutions of the perturbed jet are computed in the (U2 /U1, Beta) space:... |
| Tipo: Text |
|
| Ano: 1999 |
URL: https://archimer.ifremer.fr/doc/00480/59130/61758.pdf |
| |
| Registros recuperados: 77 | |
|
|
|
