Modal Interpretation for the Ekman Destabilization of Inviscidly Stable Baroclinic Flow in the Phillips Model
Modal Interpretation for the Ekman Destabilization of Inviscidly Stable Baroclinic Flow in the Phillips Model
复制标题
菲利普斯模型中无粘稳定斜压流的埃克曼失稳的模态解释
DOI：
--
复制
发表时间：
2010
期刊：
影响因子：
--
通讯作者：
G. Swaters
中科院分区：
文献类型：
--
作者：
G. Swaters
埃克曼边界层可能导致菲利普斯模型中斜压流的不稳定，在没有耗散的情况下，菲利普斯模型在李亚普诺夫意义上是非线性稳定的。结果表明，当且仅当与耗散相关的运动相速度位于最大和最不中性稳定罗斯贝波相速度所界定的区间之外时，菲利普斯模型中的无粘稳定斜压流的埃克曼引起的不稳定性才会发生。因此，埃克曼引起的不稳定并不对应于经典无粘斜压不稳定性中的正压和斜压罗斯贝模式的合并。两个不稳定过程之间不同的模态机制是经典理论中的亚临界斜压剪切可以被艾克曼层破坏的原因，即使在理论的零耗散极限下也是如此。
Ekman boundary layers can lead to the destabilization of baroclinic flow in the Phillips model that, in the absence of dissipation, is nonlinearly stable in the sense of Liapunov. It is shown that the Ekman-induced instability of inviscidly stable baroclinic flow in the Phillips model occurs if and only if the kinematic phase velocity associated with the dissipation lies outside the interval bounded by the greatest and least neutrally stable Rossby wave phase velocities. Thus, Ekman-induced destabilization does not correspond to a coalescence of the barotropic and baroclinic Rossby modes as in classical inviscid baroclinic instability. The differing modal mechanisms between the two instability processes is the reason why subcritical baroclinic shears in the classical theory can be destabilized by an Ekman layer, even in the zero dissipation limit of the theory.