Instability of surface‐temperature filaments in strain and shear
Instability of surface‐temperature filaments in strain and shear
复制标题
表面温度丝在应变和剪切中的不稳定性
DOI：
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发表时间：
2010
期刊：
影响因子：
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通讯作者：
M. Ambaum
中科院分区：
文献类型：
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作者：
Benjamin J. Harvey;M. Ambaum
研究了均匀应变和剪切对地表准地转温度丝稳定性的影响。应变可以稳定宽丝的扰动，但只能在有限的时间内，直到灯丝变薄到临界宽度，在此之后一些扰动可能会增长。任何细丝在实践中都不能稳定，因为在任何应变率下都会有扰动变大。最优增长摄动定义为首先达到某一阈值振幅的解，对于很大范围的参数值，可以用数值方法找到。通过非线性卷曲形成的涡旋半径与θ/S成正比，其中θ是细丝的温度异常，S是应变率，与细丝的初始尺寸无关。
The effects of uniform straining and shearing on the stability of a surface quasi‐geostrophic temperature filament are investigated. Straining is shown to stabilize perturbations for wide filaments but only for a finite time until the filament thins to a critical width, after which some perturbations can grow. No filament can be stabilized in practice, since there are perturbations that can grow large for any strain rate. The optimally growing perturbations, defined as solutions that reach a certain threshold amplitude first, are found numerically for a wide range of parameter values. The radii of the vortices formed through nonlinear roll‐up are found to be proportional to θ/s, where θ is the temperature anomaly of the filament and s the strain rate, and are not dependent on the initial size of the filament.