Carton Xavier

Carton Xavier
Université de Bretagne Occidentale | UBO · Institut Universitaire Européen de la Mer (IUEM)

Professor
Fluid mechanics, applied mathematics, physical oceanography, geophysical fluid dynamics

About

203
Publications
40,875
Reads
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3,711
Citations
Introduction
We work on vortex dynamics, on marginal sea outflows, and on geophysical fluid flow instability; see the lab teams and work at https://www.umr-lops.fr/ We have a graduate program in Marine Physics (Physical Ocea nography and Climate, Ocean Data Science, Marine Geophysics, Naval Hydrodynamics); for our graduate lectures please see https://www-iuem.univ-brest.fr/la-formation/masters-sml/mention-marine-sciences/
Additional affiliations
September 2017 - present
Université de Bretagne Occidentale
Position
  • Professor
September 2011 - present
ENSTA Bretagne
Position
  • invited lecturer (oceanography)
September 2011 - September 2013
Ecole Navale de Lanvéoc-Poulmic
Position
  • invited lecturer (fluid dynamics and oceanography)
Education
June 1999 - June 1999
Université de Bretagne Occidentale
Field of study
  • Ocean and atmosphere dynamics
September 1985 - September 1988
Ecole Normale Supérieure de Paris
Field of study
  • Geophysical Fluid Dynamics, Dynamics of the atmosphere and oceans
September 1984 - September 1985
Sorbonne Université
Field of study
  • Physics and dynamics of the atmosphere and oceans

Publications

Publications (203)
Article
Full-text available
In the Arabian Sea, southeast of the Arabian peninsula, an oceanic dipole, named the Ras Al Hadd (RAH) dipole, is formed each year, lying near the Ras Al Hadd cape. The RAH dipole is the association of a cyclonic eddy (CE) to the northeast, with an anticyclonic eddy (AE) to the southwest. This dipole intensifies in the summer monsoon and disappears...
Article
Full-text available
The merger of two surface quasi-geostrophic vortices is examined in detail. As the two vortices collapse towards each other in the merging process, they trap their external fronts between them; these fronts are inserted into the final merged vortex, where they form a central, nearly parallel, sheared velocity strip, sensitive to barotropic instabil...
Article
The Lagrangian and Eulerian surface current signatures of a low-mode internal tide propagating through a turbulent balanced flow are compared in idealized numerical simulations. Lagrangian and Eulerian total (i.e. coherent plus incoherent) tidal amplitudes are found to be similar. Compared to Eulerian diagnostics, the Lagrangian tidal signal is mor...
Article
Full-text available
In this paper, the problem of vertical shear flow instabilities at the base of a river plume and their consequences in terms of turbulent energy production and mixing is addressed. This study was carried out using 2D non-hydrostatic simulations and linear stability analysis. The initial conditions used in these simulations were similar to those obs...
Article
Full-text available
Ocean processes can locally modify the upper ocean density structure, leading to an attenuation or a deflection of sound signals. Among these phenomena, eddies cause significant changes in acoustic properties of the ocean; this suggests a possible characterization of eddies via acoustics. Here, we investigate the propagation of sound signals in the...
Article
Full-text available
Taking into account the coupling of the ocean with the atmosphere is essential to properly describe vortex dynamics in the ocean. The forcing of a circular eddy with the relative wind stress curl leads to an Ekman pumping with a nonzero area integral. This in turn creates a source or a sink in the eddy. We revisit the two point vortex-source intera...
Article
Full-text available
Coastal upwellings, due to offshore Ekman transport, are more energetic at the western boundaries of the oceans, where they are intensified by incoming Rossby waves, than at the eastern boundaries. Western boundary upwellings are often accompanied by a local vortex field. The instability of a developed upwelling front and its interaction with an ex...
Article
The science guiding the EUREC⁴A campaign and its measurements is presented. EUREC⁴A comprised roughly 5 weeks of measurements in the downstream winter trades of the North Atlantic – eastward and southeastward of Barbados. Through its ability to characterize processes operating across a wide range of scales, EUREC⁴A marked a turning point in our abi...
Article
This paper presents the paleocurrent evolution of the Persian Gulf deep water (PGDW) during the last 5000 years using faunal (foraminiferal assemblage) and non-faunal (magnetic susceptibility, sediment grain size, number of coarse relict particles and physicochemical characteristics) indicators from a 133 cm long core retrieved from the Strait of H...
Article
Full-text available
Journal website link: www.frontiersin.org I n r e v i e w Conflict of interest statement The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest Author contribution statement AA, GC and XC designed the study. AA, GC, XC and NA contrib...
Article
Full-text available
The Florida Current (FC) flows in the Straits of Florida (SoF) and connects the Loop Current in the Gulf of Mexico to the Gulf Stream (GS) in the Western Atlantic Ocean. Its journey through the SoF is at time characterized by the formation and presence of mesoscale but mostly submesoscale frontal eddies on the cyclonic side of the current. The form...
Article
Full-text available
In February 2020, a 120 km-wide freshwater plume was documented by satellite and in situ observations near the Demerara Rise (7°N/54-56°W). It was initially stratified in the upper 10 m with a freshwater content of 2 to 3 meters of Amazon water distributed down to 40 m. On February 2nd, ship transects indicate an inhomogeneous shelf structure with...
Article
Full-text available
In the Indian Ocean, salty water masses from the Persian Gulf and Red Sea are important sources of salt, heat, and nutrients. Across the Arabian Sea these outflows impact human and biological activities, their thermohaline characteristics and shapes exhibiting important spatial and seasonal variability. Knowledge of the water masses properties is i...
Article
The Eastern Kamchatka Current (EKC) is the western boundary current of the North Pacific subpolar gyre. Southeast of the Kamchatka Peninsula lies a large anticyclonic eddy, the Kamchatka Eddy (KE). This eddy is quasi-stationary. More generally, the oceanic region east of the EKC contains many eddies, several of them large and long lasting. Using su...
Article
We investigate the strong interaction between two baroclinic tripolar eddies in a three-dimensional, rapidly-rotating, continuously stratified flow under the quasi-geostrophic approximation. Each tripolar eddy consists of an anticyclonic central vortex with two oblate cyclonic vortices located above and below the anticyclone. The interaction depend...
Article
Full-text available
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): L'q' < 0, where L' and q' are the nondimensional absolute angular momentum and Ertel potential vorticity (PV), respectively. In Part II, we investigate th...
Article
Full-text available
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 fro...
Article
Full-text available
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, t...
Conference Paper
A mathematical theory of two dimensional vortices, represented by point charges, was developed at the end of the XIXth century. Recently, additional physical effects, typical of ocean dynamics, have been added to the point-vortex model; they comprise density stratification, beta effect (the variation of the Coriolis effect with latitude), the prese...
Chapter
A mathematical theory of two-dimensional vortices, represented by point charges, was developed at the end of the 19th century. Recently, additional physical effects, typical of ocean dynamics, have been added to the point-vortex model; they comprise density stratification, beta effect (the variation of the Coriolis effect with latitude), the presen...
Preprint
The retroflexion of North Brazil Current (NBC) generates large anticyclonic eddies (NBC rings : North Brazil Current rings) which drift northwestward along Northern coast of South America. Oceanographic measurements by deep acoustic floats revealed that when they hitted Lesser Antilles Arc, these rings separated vertically. an analysis of eddies fr...
Article
Full-text available
In the Bay of Biscay (north-east Atlantic), long-living eddies and the frontal activity that they induce substantially contribute to mesoscale and submesoscale dynamics. Tides and river plumes also contribute to frontal activity. Biological productivity is sensitive to river plume fronts and to external forcings (tides and wind). Considering the im...
Article
Full-text available
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-re...
Article
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 runoff can fertilize waters in the immediate vicinity or downstream of the islands, allowing phytoplankton enhancement. Here, we took the opportunity of...
Article
Full-text available
The three-layer version of the contour dynamics/surgery method is used to study the interaction mechanisms of a large-scale surface vortex with a smaller vortex/vortices of the middle layer (prototypes of intrathermocline vortices in the ocean) belonging to the middle layer of a three-layer rotating fluid. The lower layer is assumed to be dynamical...
Article
Full-text available
The theory of point vortices is used to explain the interaction of a surface vortex with subsurface vortices in the framework of a three-layer quasigeostrophic model. Theory and numerical experiments are used to calculate the interaction between one surface and one subsurface vortex. Then, the configuration with one surface vortex and two subsurfac...
Article
Full-text available
Plain Language Summary Numerical simulations of the ocean reveal the presence of numerous submesoscale eddies, vortices with radii smaller than, or equal to, 10 km. Nevertheless, their observations at depth are scarce because sampling their hydrological and dynamical structures requires very high resolution measurements. The present study presents...
Article
Full-text available
In this paper, we investigate the vortex–wall interaction on the β-plane, using a submesoscale and internal waves resolving model in an idealised context. Our results bring new insights on the dynamics of oceanic mesoscale eddies as they drift toward a western boundary. We show that there exists a strong cyclone/anticyclone asymmetry in the interac...
Article
Full-text available
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 Ou...
Preprint
Full-text available
We investigate the surface and subsurface submesoscale dynamics in the Gulf of Aden and 1 the Gulf of Oman. Our results are based on the analyses of regional numerical simulations performed 2 with a primitive equation model (HYCOM) at submesoscale permitting horizontal resolution. A 3 model zoom for each gulf is embedded in a regional mesoscale-res...
Preprint
Full-text available
The Omani Coastal Current (OCC) flowing northward along the southern coast of Oman 1 during the summer monsoon, is associated with an upwelling system. The mesoscale circulation 2 of the western Arabian Sea is dominated by energetic mesoscale eddies down to about 1000 meters 3 depth. They drive the pathways of the upwelling water masses and the Per...
Preprint
Full-text available
The Red Sea Water enters the Gulf of Aden through the Strait of Bab El Mandeb as a density current. The Red Sea Water subsequently spreads into the Gulf of Aden under the influence of surface mesoscale eddies, which dominate the surface flow, of topographic features such as rift and capes, and of the monsoon regimes. The dynamics of a bottom densit...
Article
Full-text available
The Red Sea Water enters the Gulf of Aden through the Strait of Bab El Mandeb as a density current. The Red Sea Water subsequently spreads into the Gulf of Aden under the influence of surface mesoscale eddies, which dominate the surface flow, of topographic features such as rift and capes, and of the monsoon regimes. The dynamics of a bottom densit...
Article
Full-text available
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 masse...
Article
Full-text available
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 t...
Article
Full-text available
The Red Sea Water is a warm and salty water produced in the Red Sea by evaporation induced by strong solar radiation. This dense water mass exits the Red Sea through the Strait of Bab El Mandeb, and enters the Gulf of Aden as a density current between 400 and 1000 meter depth. In the Gulf of Aden, in situ and satellites observations have shown the...
Article
Full-text available
Persian Gulf Water and Red Sea Water are salty and dense waters flowing at intermediate depths in the Gulf of Oman and the Gulf of Aden, respectively. Their spreading pathways are influence by mesoscale eddies that dominate the surface flow in both semi-enclosed basins. In situ measurements combined with altimetry indicate that Persian Gulf Water i...
Article
Full-text available
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 me...
Article
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...
Article
In the Arabian Sea, mesoscale eddies are prominent features of the circulation. They influence biological activities, tracer transport, and physical and chemical properties of the seawater. In particular, the pathways of salty water masses outflowing from the marginal seas are strongly impacted by the mesoscale eddies that evolve in the western par...
Poster
Full-text available
In the Northern Arabian Sea, the pathway of the salty Persian Gulf Water outflowing from the Persian Gulf is strongly impacted by the mesoscale and submesoscale features which evolve in the Sea of Oman and around the Arabian Peninsula. We use ARGO floats colocalized with eddies detected in the Arabian Sea for the period 2000-2015 from altimetric da...
Article
Full-text available
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). Flu...
Preprint
Full-text available
Deformation flows are 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), various fixed obstacles (submerged obstacles, continental boundaries). Fluid structu...
Article
Full-text available
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 sensitiv...
Article
Full-text available
High-resolution hydrographic measurements reveal the presence of three intrathermocline eddies (ITEs) embedded within a loop current eddy. 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 wi...
Article
We investigate families of finite core vortex quartets in mutual equilibrium in a two-layer quasigeostrophic 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 positive potential vorticity anomaly, while the two...
Article
Within the framework of the quasi-geostrophic approximation, the interactions of two identical initially circular vortex patches are studied using the contour dynamics/surgery method. The cases of barotropic vortices and of vortices in the upper layer of a two-layer fluid are considered. Diagrams showing the end states of vortex interactions and, i...
Article
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...
Article
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 t...
Article
Full-text available
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...
Article
Full-text available
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...
Article
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. T...
Article
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 adva...
Article
Full-text available
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 t...
Article
The effect of a bottom slope on the merger of two identical Rankine vortices is investigated in a two-dimensional, quasi-geostrophic, incompressible fluid. When two cyclones initially lie parallel to the slope, and more than two vortex diameters away from the slope, the critical merger distance is unchanged. When the cyclones are closer to the slope,...
Article
The Lofoten Vortex (LV), a quasi-permanent anticyclonic eddy in the Lofoten Basin of the Norwegian Sea, is investigated with an eddy-permitting primitive equation model nested into the ECCO2 ocean state estimate. The LV, as simulated by the model, extends from the sea surface to the ocean bottom at about 3000 m and has the subsurface core between 5...
Article
Full-text available
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...