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| Registros recuperados: 77 | |
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| 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 |
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| 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 |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00343/45406/44921.pdf |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00600/71246/69617.pdf |
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| 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 |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00589/70153/68140.pdf |
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| 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 |
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| 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 |
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| Dulaquais, Gabriel; Boye, Marie; Middag, Rob; Owens, Stephanis; Puigcorbe, Viena; Buesseler, Ken; Masque, Pere; De Baar, Hein J. W.; Carton, Xavier. |
| Dissolved cobalt (DCo; <0.2 µm; 14 to 93 pM) and the apparent particulate cobalt (PCo; >0.2 µm; <1 to 15 pM) were determined in the upper water column (<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 (>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 |
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| 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 |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00266/37729/35735.pdf |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| 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 |
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| Registros recuperados: 77 | |
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