Formation and stability of tripolar vortices in stratified geostrophic flows
Formation and stability of tripolar vortices in stratified geostrophic flows
复制标题
分层地转流中三极涡的形成及其稳定性
DOI：
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发表时间：
1999
期刊：
影响因子：
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通讯作者：
X. Carton
中科院分区：
文献类型：
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作者：
Stéphanie Corréard;X. Carton
在两层准地转模型中研究了三极涡旋的形成、平稳性和稳定性。在 f 平面上，这些三极子由圆形孤立涡旋的正压和斜压不稳定性形成。对于这些圆形涡流，这里考虑了分段恒定和连续的各种水平和垂直位涡分布。首先，针对简正模扰动计算它们的线性稳定性。然后，通过伪谱和轮廓手术代码研究了它们在椭圆初始扰动下的非线性演化。人们发现两种类型的斜压三极子是由这些不稳定性产生的：表面强化结构用于主导正压不稳定性，拱形三极子用于更多斜压涡旋。最后研究了这些三极子的平稳性及其对初始干扰或β效应作用的稳定性。
The formation, stationarity and stability of tripolar vortices is investigated in a two-layer quasi-geostrophic model. On the f-plane, these tripoles form from the barotropic and baroclinic instabilities of circular isolated vortices. Various horizontal and vertical potential vorticity distributions, both piecewise-constant and continuous, are considered here for these circular vortices. First, their linear stability is computed for normal-mode perturbations. Then, their nonlinear evolution with an elliptical initial perturbation is studied by means of a pseudo-spectral and of a contour surgery code. Two types of baroclinic tripoles are found to result from these instabilities: surface-intensified structures for dominant barotropic instability, arch-shaped tripoles for more baroclinic vortices. The stationarity of these tripoles and their stability to initial disturbances or to the action of beta-effect is finally investigated.