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首页> 外文期刊>Journal of Physical Oceanography >The Energetics of Centrifugal Instability
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The Energetics of Centrifugal Instability

机译：离心不稳定的能量学

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摘要

It has been shown recently that the California Undercurrent (CUC), and possibly poleward eastern boundary currents in general, generate mixing events through centrifugal instability (CI). Conditions favorable for CI are created by the strong horizontal shears developed in turbulent bottom layers of currents flowing in the direction of topographic waves. At points of abrupt topographic change, like promontories and capes, the coastal current separates from the boundary and injects gravitationally stable but dynamically unstable flow into the interior. The resulting finite-amplitude development of the instability involves overturnings and diabatic mixing. The purpose of this study is to examine the energetics of CI in order to characterize it as has been done for other instabilities and develop a framework in which to estimate its regional and global impacts. This study argues that CI is very efficient at mixing and possibly approaches what is thought to be the maximum efficiency for turbulent flows. The authors estimate that 10% of the initial energy in a CUC-like current is lost to either local mixing or the generation of unbalanced flows. The latter probably leads to nonlocal mixing. Thus, centrifugal instability is an effective process by which energy is lost from the balanced flow and spent in mixing neighboring water masses. The mixing is regionally important but of less global significance given its regional specificity.
机译：最近有研究表明，加利福尼亚的暗流（CUC），以及总体上可能是极向东的东部边界流，通过离心失稳（CI）产生混合事件。有利于CI的条件是由在地形波方向上流动的湍流底层中形成的强大水平剪切力创造的。在陡峭的地形变化点（如海角和海角），沿海水流与边界分离，并将重力稳定但动态不稳定的流动注入内部。所产生的不稳定性的有限幅度发展包括倾覆和非绝热混合。这项研究的目的是检查CI的能量学，以像其他不稳定性一样描述其特征，并开发一个框架来估计其区域和全球影响。这项研究认为CI在混合方面非常有效，并且可能接近湍流的最大效率。作者估计，在类似CUC的电流中，有10％的初始能量会因局部混合或不平衡流的产生而损失。后者可能导致非本地混合。因此，离心不稳定是一种有效的过程，通过该过程能量从平衡流中流失，并浪费在混合附近的水团中。混合具有区域重要性，但鉴于其区域特殊性，其重要性不高。

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