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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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| 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 |
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| 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 |
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| 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 |
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