Consulta: creatorFacets:"Carton, Xavier"
Registros recuperados: 77
Data/hora: 05/06/2024 02:41:41

Instability of a two-step Rankine vortex in a reduced gravity QG model
Provedor de dados: 5
Autores: Perrot, Xavier; Carton, Xavier.
We investigate the stability of a steplike Rankine vortex in a one-active-layer, reduced gravity, quasi-geostrophic model. After calculating the linear stability with a normal mode analysis, the singular modes are determined as a function of the vortex shape to investigate short-time stability. Finally we determine the position of the critical layer and show its influence when it lies inside the vortex.
Tipo: Text
Palavras-chave: Vortex dynamics; Instability; Normal/Singular modes; Critical layer.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00202/31360/31183.pdf

Hydrology and circulation in the Strait of Hormuz and the Gulf of Oman - Results from the GOGP99 experiment: 2. Gulf of Oman - art. no. C12038
Provedor de dados: 5
Autores: Pous, Stephane; Carton, Xavier; Lazure, Pascal.
Hydrological, ADCP, and drifting buoy data obtained during the GOGP99 Experiment in October and early November 1999 are analyzed to describe the Persian Gulf Water (PGW) core and the regional circulation in the Gulf of Oman. The warm and salty PGW core flows out of the Strait of Hormuz heading southeastward unto (25degrees20'N, 57degreesE), approximately. From there, it cascades down the continental slope, veers southwestward, and joins the Omani coast near (24degrees50'N, 56degrees50'E) to form a slope current. This PGW current has then thermohaline maxima on isopycnal sigma(0) = 26.5, near 220 m depth. Its thermohaline characteristics decrease along its progression to Ra's al Hadd ( and then offshore into the Arabian Sea) but maintain a sharp contrast...
Tipo: Text
Palavras-chave: Persian Gulf Water outflow; Regional circulation; Gulf of Oman.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-390.pdf

Arms winding around a meddy seen in seismic reflection data close to the Morocco coastline
Provedor de dados: 5
Autores: Menesguen, Claire; Hua, Bach-lien; Carton, Xavier; Klingelhoefer, Frauke; Schnurle, Philippe; Reichert, C.
The North Atlantic temperature and salinity distributions are strongly influenced by the existence of Mediterranean eddies (meddies) which significantly contribute to the transport of the warm and salty Mediterranean Water along different pathways. The most common pathways are observed to be North and West of the Canary Current. However, a 2011 seismic reflection cruise conducted by BGR and Ifremer near the North-Western African margin of Morocco, MIRROR Leg 2, revealed the presence of a meddy south of the Azores front and very close to the Morocco coastline. This unusual location of a strong Mediterranean Water anomaly is confirmed by other data. Moreover, meddies are long-lived structures whose dynamics and dissipation are not yet completely understood....
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00074/18499/16046.pdf

A Conservative Model for Nonlinear Dynamics in a Stratified, Rotating Fluid
Provedor de dados: 5
Autores: Filatoff, Nicolas; Carton, Xavier.
We present a set of equations describing the nonlinear dynamics of flows constrained by environmental rotation and stratification (Rossby numbers Ro∈[0.1,0.5] and Burger numbers of order unity). The fluid is assumed incompressible, adiabatic, inviscid and in hydrostatic balance. This set of equations is derived from the Navier Stokes equations (with the above properties), using a Rossby number expansion with second order truncation. The resulting model has the following properties: 1) it can represent motions with moderate Rossby numbers and a Burger number of order unity; 2) it filters inertia-gravity waves by assuming that the divergence of horizontal velocity remains small; 3) it is written in terms of a single function of space and time (pressure,...
Tipo: Text
Palavras-chave: Incompressible and Stratified Fluids; Intermediate Model; Rossby Number; Burger Number; Conservation Properties; Energy; Potential Vorticity.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00600/71195/69561.pdf

Instability of the Mediterranean Water undercurrents southwest of Portugal: effects of baroclinicity and of topography
Provedor de dados: 5
Autores: Cherubin, Laurent; Carton, Xavier; Paillet, Jerome; Morel, Yann; Serpette, Alain.
Southwest of Portugal, in situ data show that part of the mesoscale variability of the Mediterranean Water undercurrents is triggered by topographic effects (near capes and submarine canyons), and is driven by a dominantly baroclinic instability. The vertical alignment of these undercurrents observed at sites of eddy formation is indeed favorable to baroclinic instability. This instability is materialized by the formation of filaments and of small eddies in the Portimao canyon and of meddles near Cape Saint Vincent and near the Estramadura Promontory. Hydrological data and float trajectories reveal that these eddies have a baroclinic structure. Near Portimao canyon, the variation of the potential vorticity of the undercurrents again proves their...
Tipo: Text
Palavras-chave: Eau méditerranéenne; Sous-courants; Instabilité barocline; "meddies"; Atlantique nord-est; Mediterranean Water; Undercurrents; Baroclinic instability; Meddies; NE Atlantic.
Ano: 2000
URL: http://archimer.ifremer.fr/doc/00255/36632/35219.pdf

EUREC4A
Provedor de dados: 5
Autores: Stevens, Bjorn; Bony, Sandrine; Farrell, David; Ament, Felix; Blyth, Alan M.; Fairall, Christopher W.; Karstensen, Johannes; Quinn, Patricia K.; Speich, Sabrina; Acquistapace, Claudia; Aemisegger, Franziska; Albright, Anna Lea; Bellenger, Hugo; Bodenschatz, Eberhard; Caesar, Kathy-ann; Chewitt-lucas, Rebecca; De Boer, Gijs; Delanoë, Julien; Denby, Leif Christopher; Ewald, Florian; Fildier, Benjamin; Forde, Marvin; George, Geet; Gross, Silke; Hagen, Martin; Hausold, Andrea; Heywood, Karen J.; Hirsch, Lutz; Jacob, Marek; Jansen, Friedhelm; Kinne, Stefan; Klocke, Daniel; Kölling, Tobias; Konow, Heike; Lothon, Marie; Mohr, Wiebke; Naumann, Ann Kristin; Nuijens, Louise; Olivier, Léa; Pincus, Robert; Pöhlker, Mira L.; Reverdin, Gilles; Roberts, Gregory; Schnitt, Sabrina; Schulz, Hauke; Siebesma, Pier; Stephan, Caroline; Sullivan, Peter P; Touzé-peiffer, Ludovic; Vial, Jessica; Vogel, Raphaela; Zuidema, Paquita; Alexander, Nicola; Alves, Lyndon; Arixi, Sophian; Asmath, Hamish; Bagheri, Gholamhossein; Baier, Katharina; Bailey, Adriana; Baranowski, Dariusz B.; Baron, Aurelie; Barrau, Sébastien; Barrett, Paul Alan; Batier, Frédéric; Behrendt, Andreas; Bendinger, Arne; Beucher, Florent; Bigorre, Sebastien; Blades, Edmund; Blossey, P; Bock, Olivier; Boeing, Steven J; Bosser, Pierre; Bourras, Denis; Bouruet-aubertot, Pascale; Bower, Keith; Branellec, Pierre; Branger, Hubert; Brennek, Michal; Brewer, Alan; Brilouet, Pierre Etienne; Brügmann, Björn; Buehler, Stefan Alexander; Burke, Elmo; Burton, Ralph; Calmer, Radiance; Canonici, Jean-christophe; Carton, Xavier; Cato, Gregory; Charles, Jude Andre; Chazette, Patrick; Chen, Yanxu; Chilinski, Michal T; Choularton, Tom; Chuang, Patrick Y.; Clarke, Shamal; Coe, Hugh; Cornet, Cas; Coutris, Pierre; Couvreux, Fleur; Crewell, Susanne; Cronin, Timothy Wallace; Cui, Zhiqiang; Cuypers, Yannis; Daley, Alton; Damerell, Gillian Mary; Dauhut, Thibaut; Deneke, Hartwig M; Desbios, Jean-philippe; Dörner, Steffen; Donner, Sebastian; Douet, Vincent; Drushka, Kyla; Dütsch, Marina; Ehrlich, André; Emanual, Kerry; Emmanouilidis, Alexandros; Etienne, Jean-claude; Etienne-leblanc, Sheryl; Faure, Ghislain; Feingold, Graham; Ferrero, Luca; Fix, Andreas; Flamant, Cyrille; Flatau, Piotr J.; Foltz, Gregory R.; Forster, Linda; Furtuna, Iulian; Gadian, Alan; Galewsky, Joseph; Gallagher, Martin; Gallimore, Peter; Gaston, Cassandra J.; Gentemann, Chelle; Geyskens, Nicolas; Giez, Andreas; Gollop, John; Gouirand, Isabelle; Gourbeyre, Christophe; De Graaf, Dörte; De Groot, Geiske E.; Grosz, Robert; Güttler, Johannes; Gutleben, Manuel; Hall, Kashawn; Harris, George; Helfer, Kevin Christopher; Henze, Dean; Herbert, Calvert; Holanda, Bruna; Ibanez-landeta, Antonio; Intrieri, Janet M.; Iyer, Suneil; Julien, Fabrice; Kalesse, Heike; Kazil, Jan; Kellman, Alexander; Kidane, Abiel T.; Kirchner, Ulrike; Klingebiel, Marcus; Körner, Mareike; Kremper, Leslie Ann; Kretzschmar, Jan; Krüger, Ovid; Kumala, Wojciech; Kurz, Armin; L'Hégaret, Pierre; Labaste, Matthieu; Lachlan-cope, Tom A.; Laing, Arlene; Landschützer, Peter; Lang, Theresa; Lange Vega, Diego; Lange, Ingo; Laplace, Clément; Lavik, Gaute; Laxenaire, Rémi; Le Bihan, Caroline; Leandro, Mason; Lefèvre, Nathalie; Lena, Marius; Leschow, Donald; Li, Qiang; Lloyd, Gary; Los, Sebastian; Losi, Niccolò; Lovell, Oscar; Luneau, Christopher; Makuch, Przemyslaw; Malinowski, Szymon P; Manta, Gaston; Marinou, Eleni; Marsden, Nicholas; Masson, Sebastien; Maury, Nicolas; Mayer, Bernhard; Mayers-als, Margarette; Mazel, Christophe; Mcgeary, Wayne; Mcwilliams, James C.; Mech, Mario; Mehlmann, Melina; Meroni, Agostino Niyonkuru; Mieslinger, Theresa; Minikin, Andreas; Minnett, Peter; Möller, Gregor; Morfa Avalos, Yanmichel; Muller, Caroline; Musat, Ionela; Napoli, Anna; Neuberger, Almuth; Noisel, Christophe; Noone, David C; Nordsiek, Freja; Nowak, Jakub L; Oswald, Lothar; Parker, Douglas J.; Peck, Carolyn; Person, Roland; Philippi, Miriam; Plueddemann, Albert J.; Pöhlker, Christopher; Pörtge, Veronika; Pöschl, Ulrich; Pologne, Lawrence; Posyniak, Michal; Prange, Marc; Quiñones Meléndez, Estefanía; Radtke, Jule; Ramage, Karim; Reimann, Jens; Renault, Lionel; Reus, Klaus; Reyes, Ashford; Ribbe, Joachim; Ringel, Maximilian; Ritschel, Markus; Rocha, Cesar Barbedo; Rochetin, Nicolas; Röttenbacher, Johannes; Rollo, Callum; Royer, Haley; Sadoulet, Pauline; Saffin, Leo; Sandiford, Sanola; Sandu, Irina; Schäfer, Michael; Schemann, Vera; Schirmacher, Imke; Schlenczek, Oliver; Schmidt, Jerome; Schröder, Marcel; Schwarzenboeck, Alfons; Sealy, Andrea; Senff, Christoph J; Serikov, Ilya; Shohan, Samkeyat; Siddle, Elizabeth; Smirnov, Alexander; Späth, Florian; Spooner, Branden; Stolla, M. Katharina; Szkólka, Wojciech; De Szoeke, Simon P.; Tarot, Stephane; Tetoni, Eleni; Thompson, Elizabeth J; Thomson, Jim; Tomassini, Lorenzo; Totems, Julien; Ubele, Alma Anna; Villiger, Leonie; Von Arx, Jan; Wagner, Thomas; Walther, Andi; Webber, Benjamin G. M.; Wendisch, Manfred; Whitehall, Shanice; Wiltshire, Anton; Wing, Allison A.; Wirth, Martin; Wiskandt, Jonathan; Wolf, Kevin; Worbes, Ludwig; Wright, Ethan; Wulfmeyer, Volker; Young, Shanea; Zhang, Cong; Zhang, Dongxiao; Ziemen, Florian; Zinner, Tobias; Zöger, Martin.
The science guiding the \EURECA campaign and its measurements are presented. \EURECA comprised roughly five weeks of measurements in the downstream winter trades of the North Atlantic — eastward and south-eastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, \EURECA marked a turning point in our ability to observationally study factors influencing clouds in the trades, how they will respond to warming, and their link to other components of the earth system, such as upper-ocean processes or, or the life-cycle of particulate matter. This characterization was made possible by thousands (2500) of sondes distributed to measure circulations on meso (200 km) and larger (500 km) scales, roughly four hundred...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00662/77410/79070.pdf

Interactions of surface and deep anticyclonic eddies in the Bay of Biscay
Provedor de dados: 5
Autores: Carton, Xavier; Le Cann, Bernard; Serpette, Alain; Dubert, Jesus.
In 1990, satellite observations revealed that an anticyclonic surface eddy (a SWODDY, for Slope Water Oceanic eDDY) followed a cycloidal trajectory north of the Iberian coast in the Bay of Biscay. To understand the mechanisms underlying such a trajectory, we study the evolution of an idealized surface eddy in a two-layer flat-bottom quasi-geostrophic model. The effect of several processes is studied, notably the presence of deep anticyclonic vorticity. This deep vorticity may result either from the tilting of the swoddy itself, or from the presence of an anticyclonic eddy of different origins, such as a meddy (Mediterranean Water EDDY). We also study the influence of a zonal coast south of the swoddy, via the "mirror effect". Firstly, a point-vortex model...
Tipo: Text
Palavras-chave: Bay of Biscay; Anticyclonic eddies; Swoddy; Meddy; Point vortex dynamics; Trajectory; Quasi-geostrophic model; In-situ observations.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00125/23589/21478.pdf

Vortex multipoles in two-layer rotating shallow-water flows
Provedor de dados: 5
Autores: Baey, Jean-michel; Carton, Xavier.
The stability of elliptically perturbed circular vortices is investigated in a two-layer shallow-water model, with constant background rotation. The fluid is bounded above and below by rigid and flat surfaces. The linear stability analysis shows that elliptical perturbations are most unstable for moderate Burger numbers and vorticity shears. Shorter waves dominate for more sheared vortices. Shallow-water and quasigeostrophic growth rates exhibit a striking similarity, except at each end of the Burger number domain. There, cyclones (anticyclones) with finite Rossby numbers are more (less) unstable than their quasi-geostrophic counterparts. A simple model gives a first-order trend for this bias.   Nonlinear model runs with initially perturbed vortices also...
Tipo: Text
Palavras-chave: Stability analysis; Vortex; Shallow water.
Ano: 2002
URL: http://archimer.ifremer.fr/doc/2002/publication-645.pdf

Vortex stability in a multi-layer quasi-geostrophic model: application to Mediterranean Water eddies
Provedor de dados: 5
Autores: Carton, Xavier; Sokolovskiy, Mikhail; Menesguen, Claire; Aguiar, Ana; Meunier, Thomas.
The stability of circular vortices to normal mode perturbations is studied in a multi-layer quasi-geostrophic model. The stratification is fitted on the Gulf of Cadiz where many Mediterranean Water (MW) eddies are generated. Observations of MW eddies are used to determine the parameters of the reference experiment; sensitivity tests are conducted around this basic case. The objective of the study is two-fold: (a) determine the growth rates and nonlinear evolutions of unstable perturbations for different three-dimensional (3D) velocity structures of the vortices, (b) check if the different structure of our idealized vortices, mimicking MW cyclones and anticyclones, can induce different stability properties in a model that conserves parity symmetry, and...
Tipo: Text
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00216/32711/31363.pdf

Head-on collisions between two quasi-geostrophic hetons in a continuously stratified fluid
Provedor de dados: 5
Autores: Reinaud, Jean N.; Carton, Xavier.
We examine the interactions between two three-dimensional quasi-geostrophic hetons. The hetons are initially translating towards one another. We address the effect of the vertical distance between the two poles (vortices) constituting each heton on the interaction. We also examine the influence of the horizontal separation between the poles within each heton. In this investigation, the two hetons are facing each other. Two configurations are possible depending on the respective locations of the like-signed poles of the hetons. When they lie at the same depth, we refer to the configuration as symmetric; the antisymmetric configuration corresponds to opposite-signed poles at the same depth. The first step in the investigation uses point vortices to represent...
Tipo: Text
Palavras-chave: Geophysical and geological flows; Quasi-geostrophic flows; Vortex dynamics.
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00277/38796/37470.pdf

Physical and remineralization processes govern the cobalt distribution in the deep western Atlantic Ocean
Provedor de dados: 5
Autores: Dulaquais, Gabriel; Boye, Marie; Rijkenberg, M. J. A.; Carton, Xavier.
The distributions of the bio-essential trace element dissolved cobalt (DCo) and the apparent particulate Co (PCo) are presented along the GEOTRACES-A02 deep section from 64(o) N to 50(o) S in the western Atlantic Ocean (longest section of international GEOTRACES marine environment program). PCo was determined as the difference between total cobalt (TCo, unfiltered samples) and DCo. DCo concentrations ranged from 14.7 pM to 94.3 pM, and PCo concentrations from undetectable values to 18.8 pM. The lowest DCo concentrations were observed in the subtropical domains, and the highest in the low-oxygenated Atlantic Central Waters (ACW), which appears to be the major reservoir of DCo in the western Atlantic. In the Antarctic Bottom Waters, the enrichment in DCo...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00241/35223/33727.pdf

The alignment of two three-dimensional quasi-geostrophic vortices
Provedor de dados: 5
Autores: Reinaud, Jean N.; Carton, Xavier.
We consider the interaction between two quasi-geostrophic vortices of height-to-width aspect ratio h/r, lying at two different vertical levels. We investigate whether such structures naturally align. In the case the vortices occupy distinct yet contiguous vertical levels, such an alignment can contribute to the growth in volume of oceanic mesoscale vortices. The other growth mechanism is the merger of vortices sharing common vertical levels. We show that there exist titled equilibrium states where vortices nearly align slantwise. Most equilibria for prolate vortices (h/r&gt;1) are stable apart in a very narrow region of the parameter space. The instability is however normally non-destructive. Pairs of oblate vortices may also be in an unstable equilibria...
Tipo: Text
Palavras-chave: Vortex dynamics; Vortex alignment; Quasi-geostrophy.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00600/71259/69643.pdf

Trapped Instability and Vortex Formation by an Unstable Coastal Current
Provedor de dados: 5
Autores: Duarte, Rui; Carton, Xavier; Capet, Xavier; Cherubin, Laurent.
This paper addresses the instability of a two-layer coastal current in a quasi-geostrophic model; the potential vorticity (PV) structure of this current consists in two uniform cores, located at different depths, with finite width and horizontally shifted. This shift allows both barotropic and baroclinic instability for this current. The PV cores can be like-signed or opposite-signed, leading to their vertical alignment or to their hetonic coupling. These two aspects are novel compared to previous studies. For narrow vorticity cores, short waves dominate, associated with barotropic instability; for wider cores, longer waves are more unstable and are associated with baroclinic processes. Numerical experiments were performed on the f-plane with a...
Tipo: Text
Palavras-chave: Stability and instability of geophysical and astrophysical flows; Vortex flows; Rotating fluids; Stability problems; Applications to physics.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00069/17999/15673.pdf

Surface signature of Mediterranean water eddies in the Northeastern Atlantic: effect of the upper ocean stratification
Provedor de dados: 5
Autores: Bashmachnikov, I.; Carton, Xavier.
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...
Tipo: Text
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00133/24424/22437.pdf

Mediterranean outflow transports and entrainment estimates from observations and high-resolution modelling
Provedor de dados: 5
Autores: Barbosa Aguiar, Ana; Peliz, A.; Neves, F.; Bashmachnikov, I.; Carton, Xavier.
We use cross-slope sections of direct current observations together with a high resolution numerical simulation to revisit estimates of transports and entrainment in the Gulf of Cadiz. We provide a three dimensional picture of the outflow from the Mediterranean into the intermediate layers of the Atlantic. In the model, the time-averaged Mediterranean Undercurrent is characterised by two cores of zonal velocity at 8°30′8°30′W: one at 500 m (in the σ1σ1 interval 31.6-31.831.6-31.8 kg m-3) and another around 1100 m (∼32.2∼32.2 kg m-3) with maximum westward velocity of 0.36 m s-1. A single well defined vein of saltier and warmer water (salinity maximum ∼36.9∼36.9 psu, 1 psu = 1 kg salt/1000 kg seawater) is found attached to the slope, centred at 1300 m...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00238/34908/33221.pdf

Explosive instability of geostrophic vortices. Part 1: baroclinic instability
Provedor de dados: 5
Autores: Carton, Xavier; Flierl, Glenn R.; Perrot, Xavier; Meunier, Thomas; Sokolovskiy, Mikhail.
In a quasi-geostrophic model, we study the baroclinic instability of a two-layer vortex. The singular unstable modes for potential vorticity anomalies are compared with the classical normal modes. Short-time singular modes are explosively unstable and, at short times, depend only on the baroclinic component of the flow. As time progresses, they evolve towards the normal modes and their sensitivity to flow parameters is explored. Asymptotic solutions are provided.
Tipo: Text
Palavras-chave: Quasi-geostrophic equations; Inviscid flows; Vortex stability; Normal or singular modes; Parametric resonance.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00002/11352/7925.pdf

Campagne SEMANE 2002. Rapport de données CTD-O2
Provedor de dados: 5
Autores: Billant, Andre; Branellec, Pierre; Carton, Xavier.
The SEMANE experiments initiated by SHOM in 1995 have collected a large set of hydrological and current measurements aiming at characterizing the paths of Med water on the Iberian slope, as well as the variations of these paths. These variations include both eddy fluctuations induced by instability of the sub currents or by topography, and the longer term variations (at seasonal and interannual timescale). The 2002 experiment has renewed the 3 high-resolution CTD-LADCP (8.20W, 6.15W, 35.50N) in the gulf of Cadiz, to complement the previous realizations and to better assess the interannual variations (sections achieved at the same period of the year). The first analyses of previous experimental data both in stationary inverse modeling and for prognostic...
Tipo: Text
Ano: 2004
URL: http://archimer.ifremer.fr/doc/00210/32145/30602.pdf

A model of the general circulation in the Persian Gulf and in the Strait of Hormuz: Intraseasonal to interannual variability
Provedor de dados: 5
Autores: Pous, Stephane; Lazure, Pascal; Carton, Xavier.
Previous studies modeling the circulation and thermohaline structure in the Persian Gulf have suggested that interannual variability and vertical mixing processes could explain the model biases when compared to the few observations available. Here, a realistic, interannual, high-resolution model of the Persian Gulf is presented, validated against observations and then used to describe the intraseasonal to interannual variability in the circulation, water mass formation and exchange through the Strait of Hormuz. Sensitivity experiments to model settings, in particular vertical mixing parameterizations, have been performed in order to have the best comparison with all available observations. Main circulation and water mass characteristics correspond well to...
Tipo: Text
Palavras-chave: Persian Gulf; Strait of Hormuz; Numerical model; Hydrology; Currents; Interannual variability.
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00244/35563/35324.pdf

The interaction between two oppositely travelling, horizontally offset, antisymmetric quasi-geostrophic hetons
Provedor de dados: 5
Autores: Reinaud, Jean N.; Carton, Xavier.
We investigate numerically the nonlinear interactions between hetons. Hetons are baroclinic structures consisting of two vortices of opposite sign lying at different depths. Hetons are long-lived. They most often translate (they can sometimes rotate) and therefore they can noticeably contribute to the transport of scalar properties in the oceans. Heton interactions can interrupt this translation and thus this transport, by inducing a reconfiguration of interacting hetons into more complex baroclinic multipoles. More specifically, we study here the general case of two hetons, which collide with an offset between their translation axes. For this purpose, we use the point vortex theory, the ellipsoidal vortex model and direct simulations in the...
Tipo: Text
Palavras-chave: Baroclinic flows; Geophysical and geological flows; Quasi-geostrophic flows.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00333/44401/44157.pdf

The Role of Curvature in Modifying Frontal Instabilities. Part II: Application of the Criterion to Curved Density Fronts at Low Richardson Numbers
Provedor de dados: 5
Autores: Buckingham, Christian; Gula, Jonathan; Carton, Xavier.
We continue our study of the role of curvature in modifying frontal stability. In Part I, we obtained an instability criterion valid for curved fronts and vortices in gradient wind balance (GWB): Φ′ = L′q′ &lt; 0, where L′ and q′ are the nondimensional absolute angular momentum and Ertel potential vorticity (PV), respectively. In Part II, we investigate this criterion in a parameter space representative of low-Richardson-number fronts and vortices in GWB. An interesting outcome is that, for Richardson numbers near 1, anticyclonic flows increase in q′, while cyclonic flows decrease in q′, tending to stabilize anticyclonic and destabilize cyclonic flow. Although stability is marginal or weak for anticyclonic flow (owing to multiplication by L′), the...
Tipo: Text
Palavras-chave: Eddies; Fronts; Instability; Ocean circulation; Potential vorticity; Frontogenesis/frontolysis; Vortices; Angular momentum.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00677/78919/81286.pdf

Baroclinic multipole formation from heton interaction
Provedor de dados: 5
Autores: Sokolovskiy, Mikhail A.; Carton, Xavier.
In a two-layer quasi-geostrophic model, the interaction between two opposite-signed hetons (baroclinic vortex pairs) is studied analytically and numerically, for singular and finite-area vortices. For point vortices, using trilinear coordinates, it is shown that the possible evolutions depend on the deformation radius Rd: for large Rd, the layers decouple, vortices pair in each layer and their trajectories are open; for medium Rd, the exchange of opposite-sign partners between layers becomes possible; for small Rd, two other regimes appear: one where hetons remain unaltered during their evolution but follow open trajectories, and one where hetons occupy only a bounded subdomain of space at all times. Conditions for invariant co-rotation of the heton pair...
Tipo: Text
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00002/11351/7924.pdf

Eddy-topography interactions and the fate of the Persian Gulf Outflow
Provedor de dados: 5
Autores: Vic, C.; Roullet, Guillaume; Capet, Xavier; Carton, Xavier; Molemaker, Maarten Jeroen; Gula, J.
The Persian Gulf feeds a warm and salty outflow in the Gulf of Oman (northern Arabian Sea). The salt climatological distribution is relatively smooth in the Gulf of Oman, and the signature of a slope current carrying salty waters is difficult to distinguish hundreds of kilometers past the Strait of Hormuz, in contrast to other outflows of the world ocean. This study focuses on the mechanisms involved in the spreading of Persian Gulf Water (PGW) in the Gulf of Oman, using a regional primitive equation numerical simulation. The authors show that the dispersion of PGW occurs through a regime that is distinct from, for example, the one responsible for the Mediterranean outflow dispersion. The background mesoscale eddy field is energetic and participates...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00302/41332/40512.pdf

Sub-Mesoscale Frontal Instabilities in the Omani Coastal Current
Provedor de dados: 5
Autores: Morvan, Mathieu; Carton, Xavier.
The Omani Coastal Current (OCC) flowing northward along the southern coast of Oman during the summer monsoon is associated with an upwelling system. The mesoscale circulation of the western Arabian Sea is dominated by energetic mesoscale eddies down to about 1000 m depth. They drive the pathways of the upwelling water masses and the Persian Gulf Outflow water. This paper focuses on the sub-mesoscale frontal dynamics in the OCC by analyzing the results from a regional realistic numerical simulation performed with a primitive equation model. Off the Omani coast, the interaction between the upwelling fronts and the mesoscale eddies triggers the frontogenesis at play in the surface mixed layer during the summer monsoon. In spring, sub-mesoscale eddies are...
Tipo: Text
Palavras-chave: Sub-mesoscale; Fronts; Instabilities.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00623/73483/72784.pdf

Explosive instability of geostrophic vortices. Part 2: parametric instability
Provedor de dados: 5
Autores: Carton, Xavier; Meunier, Thomas; Flierl, Glenn R.; Perrot, Xavier; Sokolovskiy, Mikhail.
In a two-layer quasi-geostrophic model, a baroclinic vortex is submitted to a periodic forcing of its mean baroclinic azimuthal velocity. It is shown that parametric effects could stabilize a vortex which is baroclinically unstable in the absence of forcing. Conversely, parametric resonance can destabilize a baroclinically stable vortex, under conditions on the vortex parameters, on the ratio of layer thicknesses or on the forcing frequency.
Tipo: Text
Palavras-chave: Quasi-geostrophic equations; Inviscid flows; Vortex stability; Parametric resonance.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00002/11353/7926.pdf

Vortex merger in surface quasi-geostrophy
Provedor de dados: 5
Autores: Carton, Xavier; Ciani, Daniele; Verron, J.; Reinaud, J.; Sokolovskiy, M.
The merger of two identical surface temperature vortices is studied in the surface quasi-geostrophic 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...
Tipo: Text
Palavras-chave: Shear/strain flow; Steady states; Vortex merger; Numerical model; Surface quasi-geostrophy; Critical distance.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00323/43460/42864.pdf

Surface signature of Mediterranean water eddies in a long-term high-resolution simulation
Provedor de dados: 5
Autores: Ciani, Daniele; Carton, Xavier; Aguiar, A. C. Barbosa; Peliz, A.; Bashmachnikov, I.; Ienna, F.; Chapron, Bertrand; Santoleri, R.
We study the surface signatures of Mediterranean water eddies (Meddies) in the context of a regional, primitive equations model simulation (using the Regional Oceanic Modeling System, ROMS). This model simulation was previously performed to study the mean characteristics and pathways of Meddies during their evolution in the Atlantic Ocean. The advantage of our approach is to take into account different physical mechanisms acting on the evolution of Meddies and their surface signature, having full information on the 3D distribution of all physical variables of interest. The evolution of around 90 long-lived Meddies (whose lifetimes exceeded one year) was investigated. In particular, their surface signature was determined in sea-surface height, temperature...
Tipo: Text
Palavras-chave: Subsurface Anticyclones; Mediterranean water eddies; Satellite detection.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00405/51672/52220.pdf

Interaction between a Quasi-Geostrophic Buoyancy Filament and a Heton
Provedor de dados: 5
Autores: Reinaud, Jean N.; Carton, Xavier; Dritschel, David G.
We investigate the interaction between a heton and a current generated by a filament of buoyancy anomaly at the surface. Hetons are baroclinic dipoles consisting of a pair of vortices of opposite signs lying at different depths. Such structures have self-induced motion whenever the pair of vortices are offset horizontally. A surface buoyancy filament generates a shear flow since the density perturbation locally modifies the pressure field. The vertical shear induced by the filament offsets the vortices of the heton if vertically aligned initially. Moreover, if the vortex nearer the surface is in adverse horizontal shear with the buoyancy filament, the heton tends to move towards the filament. Conversely, if the upper vortex is in cooperative horizontal...
Tipo: Text
Palavras-chave: Quasi-geostrophy; Surface buoyancy anomaly; Vortex dynamics.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00600/71253/69631.pdf

Mesoscale dynamics in the Arabian Sea and a focus on the Great Whirl life cycle: A numerical investigation using ROMS
Provedor de dados: 5
Autores: Vic, Clement; Roullet, Guillaume; Carton, Xavier; Capet, X.
The Great Whirl (GW) is a persistent anticyclonic mesoscale eddy that is observed seasonally in the Arabian Sea during a period embedding the 3 months of the southwest monsoon (June–July–August) at a quasi-steady location. Its dynamics remain unclear despite it being one of the largest coherent vortices in the world ocean. Realistic regional numerical experiments using ROMS are performed to investigate the life cycle of the GW, which is not well resolved by sparse available in situ measurements in the region. Using a set of sensitivity experiments and an accurate temporal characterization of the eddy properties (including position, radius, depth, and vorticity) we (i) confirm the role of basin-scale downwelling Rossby waves in the GW generation, (ii)...
Tipo: Text
Palavras-chave: Arabian Sea; Indian Ocean; Great Whirl; Mesoscale dynamics; ROMS; Rossby waves.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00211/32197/30631.pdf

Mesoscale and Submesoscale Processes in the Southeast Atlantic and Their Impact on the Regional Thermohaline Structure
Provedor de dados: 5
Autores: Capuano, Tonia Astrid; Speich, Sabrina; Carton, Xavier; Blanke, Bruno.
The turbulent processes in the Cape Basin, the southeasternmost gate of the Atlantic Ocean, play a key role in the transport and mixing of upper to intermediate water masses entering the area from the Indian Ocean, making them especially relevant for the Indo-Atlantic transfer of heat and salt. In this paper, two numerical simulations at different horizontal resolutions are used to study mesoscale and submesoscale dynamics, their phenomenology, their evolution, and their impact on the local water masses. Submesoscale processes seasonally affect both, the upper and intermediate layers, but there are clear dynamical differences between the two layers. Several types of instabilities underline this spatial and temporal variability. Near the surface, mixed...
Tipo: Text
Palavras-chave: Meso- and submesoscale dynamics; Cape Basin water masses; Indo-Atlantic exchange.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00600/71247/69618.pdf

Phytoplankton competition and coexistence: Intrinsic ecosystem dynamics and impact of vertical mixing
Provedor de dados: 5
Autores: Perruche, Coralie; Riviere, Pascal; Pondaven, Philippe; Carton, Xavier.
This paper aims at studying analytically the functioning of a very simple ecosystem model with two phytoplankton species. First, using the dynamical system theory, we determine its nonlinear equilibria, their stability and characteristic timescales with a focus on phytoplankton competition. Particular attention is paid to the model sensitivity to parameter change. Then, the influence of vertical mixing and sinking of detritus on the vertically-distributed ecosystem model is investigated. The analytical results reveal a high diversity of ecosystem structures with fixed points and limit cycles that are mainly sensitive to variations of light intensity and total amount of nitrogen matter. The sensitivity to other parameters such as remineralisation, growth...
Tipo: Text
Palavras-chave: Water mixing; Dynamical system; Phytoplankton; Competition; Ecosystem; Modelling.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/2009/publication-7334.pdf

Temperature-salinity distribution in the northeastern Atlantic from ship and Argo vertical casts
Provedor de dados: 5
Autores: Bashmachnikov, I.; Neves, F.; Nascimento, A.; Medeiros, J.; Ambar, I.; Dias, J.; Carton, Xavier.
The present study defines new interpolation functions for hydrological data. These functions are applied to generate climatological maps of temperature-salinity distribution with a 25 m depth interval and a 30 km space interval (MEDTRANS data set). The data undergo rigorous initial data quality control, having passed several filtering procedures. The gridding is done on neutral density surfaces, which allows better representation of thermohaline fronts for the same gridding radius. The multi-pass Barnes optimum interpolation procedure with spatially variable size of the gridding window is used. The shape of the window accounts for the dominant along-isobath direction of water mass transport over steeply sloping topography. A local ratio of topographic to...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00266/37729/35735.pdf

2D vortex interaction in a non-uniform flow
Provedor de dados: 5
Autores: Perrot, Xavier; Carton, Xavier.
In a two-dimensional incompressible fluid, we study the interaction of two like-signed Rankine vortices embedded in a steady shear/strain flow. The numerical results of vortex evolutions are compared with the analytical results for point vortices. We show the existence of vortex equilibria, and of merger for initial distances larger than those without external flow. The evolutions depend on the initial orientation of the vortices in the external flow.
Tipo: Text
Palavras-chave: Two-dimensional incompressible flows; Vortex merger; Pseudo-spectral model.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/2009/publication-7442.pdf

Statistical Analysis of Sea Surface Temperature and Chlorophyll-a Concentration Patterns in the Gulf of Tadjourah (Djibouti)
Provedor de dados: 5
Autores: Youssouf, Moussa Omar; Memery, Laurent; Carton, Xavier.
The sea surface temperature (SST) and chlorophyll-a concentration (CHL-a) were analysed in the Gulf of Tadjourah from two set of 8-day composite satellite data, respectively from 2008 to 2012 and from 2005 to 2011. A singular spectrum analysis (SSA) shows that the annual cycle of SST is strong (74.3% of variance) and consists of warming (April-October) and cooling (November-March) of about 2.5C than the long-term average. The semi-annual cycle captures only 14.6% of temperature variance and emphasises the drop of SST during July-August. Similarly, the annual cycle of CHL-a (29.7% of variance) depicts high CHL-a from June to October and low concentration from November to May. In addition, the first spatial empirical orthogonal function (EOF) of SST (93% of...
Tipo: Text
Palavras-chave: Sea surface temperature; Chlorophyll a concentration; Singular spectrum analysis; Empirical orthogonal function; Multichannel singular spectrum.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00337/44842/44429.pdf

Submesoscale Dynamics in the Gulf of Aden and the Gulf of Oman
Provedor de dados: 5
Autores: Morvan, Mathieu; Carton, Xavier; Corréard, Stéphanie; Baraille, Rémy.
We have investigated the surface and subsurface submesoscale dynamics in the Gulf of Aden and the Gulf of Oman. Our results are based on the analyses of regional numerical simulations performed with a primitive equation model (HYCOM) at submesoscale permitting horizontal resolution. A model zoom for each gulf was embedded in a regional mesoscale-resolving simulation. In the Gulf of Aden and the Gulf of Oman, the interactions of mesoscale structures and fronts instabilities form submesoscale eddies and filaments. Rotational energy spectra show that the Gulf of Aden has a higher ratio of submesoscale to mesocale energy than the Gulf of Oman. Fast waves (internal gravity waves, tidal waves, Kelvin waves) and slow waves (Rossby waves) were characterized via...
Tipo: Text
Palavras-chave: Submesoscale instabilities; Eddies and waves; Upwelling fronts.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00645/75698/76603.pdf

On the merger of subsurface isolated vortices
Provedor de dados: 5
Autores: Ciani, Daniele; Carton, Xavier; Verron, Jacques.
Vortex merger is a phenomenon characterizing the whole class of geophysical vortices, from atmospheric storms and large oceanic eddies up to small scale turbulence. Here we focus on the merger of subsurface oceanic anticyclones in an idealized primitive equations model. This study has been motivated by past and recent observations of colliding lens-like anticyclones off of Gibraltar Strait. The critical conditions for merger (critical merger distance and time needed for merger) are determined. We will show that the predictions of classical two-dimensional merger are not verified for subsurface isolated vortices. For instance, critical merger distances will be reduced because of the vortex potential vorticity (PV) structure. The post-merger characteristics...
Tipo: Text
Palavras-chave: Subsurface isolated vortices; Peddies; Meddies; Vortex merger.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00314/42563/44982.pdf

Contrasting biogeochemical cycles of cobalt in the surface western Atlantic Ocean
Provedor de dados: 5
Autores: Dulaquais, Gabriel; Boye, Marie; Middag, Rob; Owens, Stephanis; Puigcorbe, Viena; Buesseler, Ken; Masque, Pere; De Baar, Hein J. W.; Carton, Xavier.
Dissolved cobalt (DCo; &lt;0.2 µm; 14 to 93 pM) and the apparent particulate cobalt (PCo; &gt;0.2 µm; &lt;1 to 15 pM) were determined in the upper water column (&lt;1000 m) of the western Atlantic Ocean along the GEOTRACES-A02 section (64°N to 50°S). The lowest DCo concentrations, typical of a nutrient-type distribution were observed in surface waters of the subtropical domains. Strong linear relationships between DCo and phosphate (P) as well as meridional gradients of decreasing DCo from high latitudes were characterized and both linked to the Co biological requirement. External sources such as the Amazon and the atmospheric deposition were found to contribute significantly (&gt;10%) to the DCo stock of the mixed layer in the equatorial and north...
Tipo: Text
Palavras-chave: Cobalt; Biogeochemistry; Atlantic Ocean; Chemical Oceanography; GEOTRACES.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00241/35222/33732.pdf

Indo-Atlantic Exchange, Mesoscale Dynamics, and Antarctic Intermediate Water
Provedor de dados: 5
Autores: Capuano, Tonia Astrid; Speich, Sabrina; Carton, Xavier; Laxenaire, Remi.
This study evaluates the capability of eddy-permitting regional ocean models to reproduce the interocean exchange south of Africa. In this highly turbulent region, we show that the vertical structure of the horizontal flows need to be appropriately resolved to realistically advect thermocline water masses into the South Atlantic. Our results point out that a grid-spacing of 1/24 degrees on the horizontal and 50 m on the vertical homogeneously distributed are required to account for a correct transport of surface and subsurface water masses properties and their in-route transformation by mixing. Preliminary Lagrangian analyses highlight the primary role of the upper-ocean mesoscale eddies on water masses transport and fate, with a particular emphasis on...
Tipo: Text
Palavras-chave: Eddy dynamics; Indo-Atlantic exchange; AAIW.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00600/71245/69616.pdf

Hydrology and circulation in the Strait of Hormuz and the Gulf of Oman - Results from the GOGP99 experiment: 1. Strait of Hormuz - art. no. C12037
Provedor de dados: 5
Autores: Pous, Stephane; Carton, Xavier; Lazure, Pascal.
In October and early November 1999, the GOGP99 experiment collected hydrological, currentmeter, tide recorder, thermistor and drifting buoy data near the Strait of Hormuz. Data analysis provides the water mass structure in the Strait: Persian Gulf Water (PGW) core is banked against the Omani coast, while Indian Ocean Surface Water (IOSW) lies near the Iranian coast. These water masses are most often covered by a homogeneous surface layer. Thermohaline characteristics of the PGW core decrease substantially downstream, from the Persian/Arabian Gulf to the Gulf of Oman. PGW and IOSW thermohaline characteristics and distribution also exhibit notable changes at periods shorter than a month as shown by repeated hydrological sections. The tidal signal measured...
Tipo: Text
Palavras-chave: Oceanography; Hydrology; Hormuz.
Ano: 2004
URL: http://archimer.ifremer.fr/doc/2004/publication-389.pdf

Evidence of Mediterranean Water dipole collision in the Gulf of Cadiz
Provedor de dados: 5
Autores: L'Hegaret, Pierre; Carton, Xavier; Ambar, Isabel; Menesguen, Claire; Hua, Bach Lien; Cherubin, Laurent; Aguiar, Ana; Le Cann, Bernard; Daniault, Nathalie; Serra, Nuno.
A collision of Mediterranean Water dipoles in the Gulf of Cadiz is studied here, using data from the MedTop and Semane experiments. First, a Mediterranean Water eddy (meddy) was surveyed hydrologically in November 2000 southwest of Cape Saint Vincent. Then, this meddy drifted northeastward from this position, accompanied by a cyclone (detected only via altimetry), thus forming a first dipole. In February 2001, a dipole of Mediterranean Water was measured hydrologically just after its formation near Portimão Canyon. This second dipole drifted southwestward. The western and eastern meddies had hydrological radii of about 22 and 25 km, respectively, with corresponding temperature and salinity maxima of (13.45°C, 36.78) and (11.40°C, 36.40). Rafos float...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00204/31565/29986.pdf

Structure and Temporal Variability of Mediterranean Water in Hydrological and Marine Seismic Data South of Portimao Canyon (Gulf of Cadiz), from 1999 to 2002
Provedor de dados: 5
Autores: Quentel, Elise; Carton, Xavier; Gutscher, Marc-andre.
Hydrological and marine seismic data, collected in the Gulf of Cadiz (respectively in July 1999, 2000, 2001 and 2002, and in April 2000 and 2001) are analysed to reveal the various structures of Mediterranean Water (MW). Both the hydrological and seismic data clearly identify the MW undercurrents on the Iberian slope, detached MW eddies (meddies and a cyclone) and smaller fragments of MW (filaments and small eddies). Seismic reflectivity and synthetic reflectivity computed from hydrology, indicate that strong acoustic reflectors, associated with 8 - 64 m thick homogeneous water layers, are found above and below meddies and filaments, around the MW undercurrents, but mostly in the lower part of cyclones and below submesoscale eddies. Reflectors are also...
Tipo: Text
Palavras-chave: Mediterranean Water; Eddies; Undercurrent; Layering; Hydrological Data; Seismic Reflectivity; Submesoscale Structures.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00129/24006/21962.pdf

The Interaction of Two Surface Vortices Near a Topographic Slope in a Stratified Ocean
Provedor de dados: 5
Autores: 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

Seismic imaging of the ocean internal structure: A new tool in physical oceanography?
Provedor de dados: 5
Autores: 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

Interaction between a surface quasi-geostrophic buoyancy anomaly jet and internal vortices
Provedor de dados: 5
Autores: 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

Cyclones and Anticyclones in Seismic Imaging
Provedor de dados: 5
Autores: 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

Characteristics of surface signatures of Mediterranean water eddies
Provedor de dados: 5
Autores: 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 &gt;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

On instability of elliptical hetons
Provedor de dados: 5
Autores: Sokolovskiy, Mikhail; Verron, Jacques; Carton, Xavier; Gryanik, Vladimir.
Using the method of contour surgery, we examine the evolution of an initially vertically aligned elliptical heton. A classification of quasi-stable and unstable regimes for the case of two-layered vortex structure is suggested.
Tipo: Text
Palavras-chave: Heton; Vortex instability; Elliptical vortex.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-7441.pdf

The life cycle of submesoscale eddies generated by topographic interactions
Provedor de dados: 5
Autores: 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

Monitoring the Influence of the Mesoscale Ocean Dynamics on Phytoplanktonic Plumes around the Marquesas Islands Using Multi-Satellite Missions
Provedor de dados: 5
Autores: 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

Integrable motion of a vortex dipole in an axisymmetric flow
Provedor de dados: 5
Autores: 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

A Process Study of the Wind-Induced Circulation in the Persian Gulf
Provedor de dados: 5
Autores: 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

The Role of Curvature in Modifying Frontal Instabilities. Part I: Review of Theory and Presentation of a Nondimensional Instability Criterion
Provedor de dados: 5
Autores: 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 &lt; 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

Interaction between an eddy and a zonal jet - Part I. One-and-a-half-layer model
Provedor de dados: 5
Autores: 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

Structure and Dynamics of the Ras al Hadd Oceanic Dipole in the Arabian Sea
Provedor de dados: 5
Autores: 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

Heat Content Anomaly and Decay of Warm‐core Rings: the Case of the Gulf of Mexico
Provedor de dados: 5
Autores: 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

Interaction between an eddy and a zonal jet - Part II. Two-and-a-half-layer model
Provedor de dados: 5
Autores: 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

Interaction of an along-shore propagating vortex with a vortex enclosed in a circular bay
Provedor de dados: 5
Autores: 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

Mesoscale variability in the Arabian Sea from HYCOM model results and observations: impact on the Persian Gulf Water path
Provedor de dados: 5
Autores: 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

Vortex Interactions Subjected to Deformation Flows: A Review
Provedor de dados: 5
Autores: Koshel, Konstantin V.; Ryzhov, Eugene A.; Carton, Xavier.
Deformation flows are the flows incorporating shear, strain and rotational components. These flows are ubiquitous in the geophysical flows, such as the ocean and atmosphere. They appear near almost any salience, such as isolated coherent structures (vortices and jets) and various fixed obstacles (submerged obstacles and continental boundaries). Fluid structures subject to such deformation flows may exhibit drastic changes in motion. In this review paper, we focus on the motion of a small number of coherent vortices embedded in deformation flows. Problems involving isolated one and two vortices are addressed. When considering a single-vortex problem, the main focus is on the evolution of the vortex boundary and its influence on the passive scalar motion....
Tipo: Text
Palavras-chave: Shear flow; Deformation flow; Point vortex; Elliptic vortex; Chaotic dynamics; Parametric instability; Stability islands.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00600/71243/69613.pdf

A census of Meddies in a long-term high-resolution simulation
Provedor de dados: 5
Autores: 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

Vortex formation by unstable oceanic jets
Provedor de dados: 5
Autores: 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

Optimal Perturbations of an Oceanic Vortex Lens
Provedor de dados: 5
Autores: Meunier, Thomas; Menesguen, Claire; Carton, Xavier; Le Gentil, Sylvie; Schopp, Richard.
The stability properties of a vortex lens are studied in the quasi geostrophic (QG) framework using the generalized stability theory. Optimal perturbations are obtained using a tangent linear QG model and its adjoint. Their fine-scale spatial structures are studied in details. Growth rates of optimal perturbations are shown to be extremely sensitive to the time interval of optimization: The most unstable perturbations are found for time intervals of about 3 days, while the growth rates continuously decrease towards the most unstable normal mode, which is reached after about 170 days. The horizontal structure of the optimal perturbations consists of an intense counter-shear spiralling. It is also extremely sensitive to time interval: for short time...
Tipo: Text
Palavras-chave: Vortex lenses; Intrathermocline eddies; Instability; Optimal perturbations.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00454/56605/58297.pdf

Hetonic quartets in a two-layer quasi-geostrophic flow: V-states and stability
Provedor de dados: 5
Autores: Reinaud, J. N.; Sokolovskiy, M. A.; Carton, Xavier.
We investigate families of finite core vortex quartets in mutual equilibrium in a two-layer quasi-geostrophic flow. The finite core solutions stem from known solutions for discrete (singular) vortex quartets. Two vortices lie in the top layer and two vortices lie in the bottom layer. Two vortices have a positive potential vorticity anomaly, while the two others have negative potential vorticity anomaly. The vortex configurations are therefore related to the baroclinic dipoles known in the literature as hetons. Two main branches of solutions exist depending on the arrangement of the vortices: the translating zigzag-shaped hetonic quartets and the rotating zigzag-shaped hetonic quartets. By addressing their linear stability, we show that while the rotating...
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00600/71246/69617.pdf

Turbulent dispersion properties from a model simulation of the western Mediterranean Sea
Provedor de dados: 5
Autores: Nefzi, H.; Elhmaidi, D.; Carton, Xavier.
Using a high-resolution primitive equation model of the western Mediterranean Sea, we analyzed the dispersion properties of a set of homogeneously distributed, passive particle pairs. These particles were initially separated by different distances D-0 (D-0 = 5.55, 11.1 and 16.65 km), and were seeded in the model at initial depths of 44 and 500 m. This realistic ocean model, which reproduces the main features of the regional circulation, puts into evidence the three well-known regimes of relative dispersion. The first regime due to the chaotic advection at small scales lasts only a few days (3 days at 44m depth, a duration comparable with the integral timescale), and the relative dispersion is then exponential. In the second regime, extending from 3 to 20...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00192/30318/28791.pdf

Hydrological Structure, Circulation and Water Mass Transport in the Gulf of Cadiz
Provedor de dados: 5
Autores: Alves, Jose Miguel Rodrigues; Carton, Xavier; Ambar, Isabel.
Hydrological and LADCP data from four experiments at sea (Semane 1999, 2000/1 2000/3, 2001) are used to describe the structure and circulation of Mediterranean Water in the Gulf of Cadiz. These data were gathered on meridional sections along 8?20′W and 6?15′W and between these longitudes on a zonal section along 35?50′N. The mesoscale and the submesoscale structures (Mediterranean Water Undercurrents, meddies, cyclones) observed along these sections are characterized in terms of thermohaline properties and of velocity. The transports of mass and salt in each class of density (North Atlantic Central Water, Mediterranean Water, North Atlantic Deep Water) are computed with an inverse model. The model indicates a general eastward flux in the Central Water...
Tipo: Text
Palavras-chave: Mediterranean Water; Gulf of Cadiz; Hydrology; Water Masses; Regional Scale Circulation; Inverse Model; Transport.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00129/24005/21961.pdf

Western boundary upwelling dynamics off Oman
Provedor de dados: 5
Autores: Vic, Clement; Capet, Xavier; Roullet, Guillaume; Carton, Xavier; ,.
Despite its climatic and ecosystemic significance, the coastal upwelling that takes place off Oman is not well understood. A primitive-equation, regional model forced by climatological wind stress is used to investigate its dynamics and to compare it with the better-known Eastern Boundary Upwellings (EBUs). The solution compares favorably with existing observations, simulating well the seasonal cycles of thermal structure, surface circulation (mean and turbulent), and sea-surface temperature (SST). There is a 1.5-month lag between the maximum of the upwelling-favorable wind-stress-curl forcing and the oceanic response (minima in sea-surface height and SST), which we attribute to onshore-propagating Rossby waves. A southwestward-flowing undercurrent...
Tipo: Text
Palavras-chave: Oman; Upwelling; Arabian sea; ROMS; Rossby waves; Eddy kinetic energy.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00382/49350/49752.pdf

A Process Study of the Tidal Circulation in the Persian Gulf
Provedor de dados: 5
Autores: Pous, Stephane; Carton, Xavier; Lazure, Pascal.
A homogeneous shallow-water model with free surface is used to model the tidal circulation in the Persian Gulf. The numerical finite-difference model includes harmonic diffusion of horizontal momentum and quadratic bottom friction, it has a 9 km mesh size and it is forced by 7 tidal components at its southern boundary. High precision bathymetric data are used to obtain the bottom topography. The numerical model is run for more than a year. The results are the following: 1) The model accurately reproduces the tidal phase and amplitude observed at 42 tidal gauges in the region. This accuracy is attributed to the presence of the 7 components which are able to interact nonlinearly; 2) The amphidromic points are also well positioned by the model due to a proper...
Tipo: Text
Palavras-chave: Persian Gulf; Barotropic Tide; Hydrodynamical Modeling; Comparison with Data.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00284/39520/38013.pdf

An index to distinguish surface and subsurface intensified vortices from surface observations
Provedor de dados: 5
Autores: Assassi, Charefeddine; Morel, Y.; Vandermeirsch, Frederic; Chaigneau, A.; Pegliasco, C.; Morrow, R.; Colas, F.; Fleury, S.; Carton, Xavier; Klein, Patrice; Cambra, R.
In this study, we first show that it is difficult to reconstruct the vertical structure of vortices using only surface observations. In particular we show that the recent SQG and ISQG methods systematically lead to surface intensified vortices and those subsurface intensified vortices are thus not correctly modelled.  We then investigate the possibility to distinguish between surface and subsurface intensified eddies from surface data only, using the sea surface height and the sea surface temperature available from satellite observations. A simple index, based on the ratio of the sea surface temperature anomaly and the sea level anomaly, is proposed. While the index is expected to give perfect results for isolated vortices, we show that in a complex...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00343/45406/44921.pdf

Slow quasigeostrophic unstable modes of a lens vortex in a continuously stratified flow
Provedor de dados: 5
Autores: Nguyen, Hai Yen; Hua, Bach-lien; Schopp, Richard; Carton, Xavier.
This work addresses the linear dynamics underlying the formation of density interfaces at the periphery of energetic vortices, well outside the vortex core, both in the radial and axial directions. We compute numerically the unstable modes of an anticyclonic Gaussian vortex lens in a continuously stratified rotating fluid. The most unstable mode is a slow mode, associated with a critical layer instability located at the vortex periphery. Although the most unstable disturbance has a characteristic vertical scale which is comparable to the vortex height, interestingly, the critical levels of the successively fastest growing modes are closely spaced at intervals along the axial direction that are much smaller than the vortex height.
Tipo: Text
Palavras-chave: Quasigeostrophic model; Vortices; Stratified flow; Critical level; Flow instability.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00074/18520/16331.pdf

A seasonal dipolar eddy near Ras Al Hamra (Sea of Oman)
Provedor de dados: 5
Autores: L'Hegaret, Pierre; Lacour, Leo; Carton, Xavier; Roullet, Guillaume; Baraille, Remy; Correard, Stephanie.
Trajectories and hydrological data from two Argo floats indicate that warm and salty water at 200–300-m depths was ejected from the coast of Oman, near Ras al Hamra, in spring 2008, 2011, and 2012. This warm and salty water, Persian Gulf Water (PGW), once ejected from the coast, recirculated cyclonically in the western Sea of Oman, but also flowed eastward along the Iranian and Pakistani coasts. There, it was expelled seaward by mesoscale eddies as shown by other float data. Seasonal maps of salinity were computed from all available Argo floats; they showed that, in spring, PGW is present in the middle and north of the Sea of Oman, contrary to fall, when the salinity maxima lie southeast of Ras al Hadd. The ejection of PGW from Ras al Hamra is related here...
Tipo: Text
Palavras-chave: Sea of Oman; Outflow; Eddies; Argo floats.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00171/28206/33894.pdf

Mesoscale eddies and submesoscale structures of Persian Gulf Water off the Omani coast in spring 2011
Provedor de dados: 5
Autores: L'Hegaret, Pierre; Carton, Xavier; Louazel, Stephanie; Boutin, Guillaume.
The Persian Gulf produces high-salinity water (Persian Gulf Water, PGW hereafter), which flows into the Sea of Oman via the Strait of Hormuz. Beyond the Strait of Hormuz, the PGW cascades down the continental slope and spreads in the Sea of Oman under the influence of the energetic mesoscale eddies. The PGW outflow has different thermohaline characteristics and pathways, depending on the season. In spring 2011, the Phys-Indien experiment was carried out in the Arabian Sea and in the Sea of Oman. The Phys-Indien 2011 measurements, as well as satellite observations, are used here to characterize the circulation induced by the eddy field and its impact on the PGW pathway and evolution. During the spring intermonsoon, an anticyclonic eddy is often observed at...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00600/71204/69574.pdf

Effects of Monsoon Winds and Topographical Features on the Vertical Thermohaline and Biogeochemical Structure in the Gulf of Tadjourah (Djibouti)
Provedor de dados: 5
Autores: Omar, Youssouf Moussa; Memery, Laurent; Carton, Xavier; Daher, Abdourahman; Duvielbourg, Eric.
The vertical thermohaline and biogeochemical structures of the upper layer (0 - 200 m) were studied in the Gulf of Tadjourah using high-resolution hydrographic data collected in July-August 2013, September 2013 and February 2014. During summer, the superficial layer consisted of the mixed layer (ML) extending to a depth of about 20 - 30 m followed by the thermocline located between 30 and 50 m depth. The ML was thicker in the west and the southeast where the thermal gradient and chlorophyll a concentrations were particularly high. During September, this stratification persisted but the ML became warmer and saltier and the thermocline moved slightly deeper. In February, the ML extended to about 120 m, and the thermocline was less pronounced. A comparison of...
Tipo: Text
Palavras-chave: Thermohaline; Biogeochemical Structures; Mixed Layer Depth; Thermocline; Monsoon Wind; Topography.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00601/71286/69693.pdf

The stability and the nonlinear evolution of quasi-geostrophic hetons
Provedor de dados: 5
Autores: Reinaud, J.; Carton, Xavier.
We analyse the linear stability and nonlinear evolutions of circular hetons under the quasi-geostrophic approximation. We compare results obtained with a three-layer model and with a model based on a continuous density stratification. Though the models also differ by the vertical boundary conditions, they show a remarkable similarity in the stability properties of the hetons (threshold values of vortex radius for baroclinic instability, dominant modes, growth rates, etc.), and in their nonlinear evolutions (spatial reorganization of potential vorticity by nonlinear processes, end-states of the simulations). The hetons prone to baroclinic instability often break into two hetons drifting in opposite directions, and in more hetons, for wider initial...
Tipo: Text
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-7332.pdf

Study of the stability of a large realistic cyclonic eddy
Provedor de dados: 5
Autores: De Marez, Charly; Meunier, Thomas; Morvan, Mathieu; L’hégaret, Pierre; Carton, Xavier.
We investigate the stability of a composite cyclone representative of Arabian Sea eddies using a high resolution primitive equation model. We observe that the eddy is unstable with respect to a mixed barotropic/baroclinic instability, leading to the growth of an azimuthal mode 2 perturbation. The latter deforms the eddy, which eventually evolves into a tripole after about 4 months of simulation. The presence of a critical level for the most unstable mode generates sharp fronts in the surface mixed layer where the Rossby number is large. These fronts then become unstable, and this generates submesoscale cyclones and filaments. Near these fronts, diapycnal mixing occurs, causing the potential vorticity to change sign locally, and symmetric instability to...
Tipo: Text
Palavras-chave: Mesoscale; Eddy; Instability; Submesoscale; Vortex.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00598/70967/69196.pdf

Geostrophic tripolar vortices in a two-layer fluid: Linear stability and nonlinear evolution of equilibria
Provedor de dados: 5
Autores: Reinaud, J. N.; Sokolovskiy, M. A.; Carton, Xavier.
We investigate equilibrium solutions for tripolar vortices in a two-layer quasi-geostrophic flow. Two of the vortices are like-signed and lie in one layer. An opposite-signed vortex lies in the other layer. The families of equilibria can be spanned by the distance (called separation) between the two like-signed vortices. Two equilibrium configurations are possible when the opposite-signed vortex lies between the two other vortices. In the first configuration (called ordinary roundabout), the opposite signed vortex is equidistant to the two other vortices. In the second configuration (eccentric roundabouts), the distances are unequal. We determine the equilibria numerically and describe their characteristics for various internal deformation radii. The two...
Tipo: Text
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00600/71257/69639.pdf

Intrathermocline Eddies Embedded within an Anticyclonic Vortex Ring
Provedor de dados: 5
Autores: Meunier, Thomas; Tenreiro, M.; Pallas-sanz, Enric; Ochoa, Jose; Ruiz-angulo, Angel; Portela, Esther; Cusi, Simo; Damien, Pierre; Carton, Xavier.
High‐resolution hydrographic measurements reveal the presence of three Intra‐Thermocline Eddies (ITEs) embedded within a Loop Current Eddy (LCE). ITEs are lenticular bodies of nearly homogeneous water which contrasts with the well stratified surrounding water. Their radii and thickness ranged between [19‐32] km and [150‐250] m. Negative relative vorticity within their cores (down to ‐0.85 times the Coriolis frequency), along with a large negative stratification anomaly, result in low Ertel Potential Vorticity (PV) and intense negative Ertel Potential Vorticity Anomalies (PVA). Vortex stretching and relative vorticity have comparable contributions to PVA, resulting in Burger numbers of order unity. The similarity of thermohaline properties within the ITE's...
Tipo: Text
Palavras-chave: Intrathermocline eddies; Submesoscale coherent vortices; Vortex lenses; Loop current eddy; Gulf of Mexico; Submesoscale.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00440/55122/56578.pdf

Oceanic vortex mergers are not isolated but influenced by the beta-effect and surrounding eddies
Provedor de dados: 5
Autores: De Marez, Charly; Carton, Xavier; L'Hegaret, Pierre; Meunier, Thomas; Stegner, Alexandre; Le Vu, Briac; Morvan, Mathieu.
Oceanic vortices are ubiquitous in the ocean. They dominate the sub-inertial energy spectrum, and their dynamics is key for the evolution of the water column properties. The merger of two like-signed coherent vortices, which ultimately results in the formation of a larger vortex, provides an efficient mechanism for the lateral mixing of water masses in the ocean. Understanding the conditions of such interaction in the ocean is thus essential. Here, we use a merger detection algorithm to draw a global picture of this process in the ocean. We show that vortex mergers are not isolated, contrary to the hypothesis made in most earlier studies. Paradoxically, the merging distance is well reproduced by isolated vortex merger numerical simulations, but it is...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00657/76873/78117.pdf

Deep lenses of circumpolar water in the Argentine Basin - art. no. 3007
Provedor de dados: 5
Autores: Arhan, Michel; Carton, Xavier; Piola, A; Zenk, W.
[1] Three deep anticyclonic eddies of a species only reported once before [Gordon and Greengrove, 1986] were intersected by hydrographic lines of the World Ocean Circulation Experiment (WOCE) and South Atlantic Ventilation Experiment (SAVE) programs in the Argentine Basin. The vortices are centered near 3500 m depth at the interface between North Atlantic Deep Water and Bottom Water. They have similar to1500-m-thick cores containing Lower Circumpolar Deep Water and a dynamical influence that may span up to two thirds of the water column. As one eddy was observed just downstream of the western termination of the Falkland Escarpment, a destabilization of the deep boundary current by the sudden slope relaxation is suggested as a potential cause of eddy...
Tipo: Text
Palavras-chave: Eddies and mesoscale processes; Western boundary currents; Hydrography.
Ano: 2002
URL: https://archimer.ifremer.fr/doc/00000/10057/7797.pdf