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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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| 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 |
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