Combined Effect of Rotation and Topography on Shoaling Oceanic Internal Solitary Waves
Combined Effect of Rotation and Topography on Shoaling Oceanic Internal Solitary Waves
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DOI：
10.1175/jpo-d-13-0194.1
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发表时间：
2014-04-01
影响因子：
3.5
通讯作者：
Vlasenko, Vasiliy
中科院分区：
文献类型：
--
作者：
Grimshaw, Roger;Guo, Chuncheng;Vlasenko, Vasiliy
内孤立波在近海中经常被观测到，通常用Korteweg-de弗里斯型非线性发展方程来模拟。由于这些波通常在几个惯性周期内长距离传播，地球背景旋转的影响可能很大。Kortweg-de弗里斯方程的相关扩展就是奥斯特洛夫斯基方程，它对于内波不支持定常孤立波解。最近的研究使用的渐近理论，数值模拟和实验室实验相结合的结果表明，旋转的长时间的影响是破坏的初始内部孤立波的辐射的小振幅惯性重力波，并最终出现一个连贯的，稳定的传播，非线性波包。然而，在海洋中，内孤立波往往是在多变的地形上传播的，仅这一点就可以引起内孤立波的相当戏剧性的变形和转变。因此，背景旋转和可变地形的综合影响进行了研究。然后用变系数Ostrovsky方程代替Ostrovsky方程，其系数显式依赖于空间坐标。本文给出了该方程的数值模拟结果，以及利用马萨诸塞州理工学院大气环流模式（MITgcm）对南海某断面的模拟结果。这表明，变浅和旋转的综合效应是诱导二次尾波包，诱导增强辐射的领先波。
Internal solitary waves commonly observed in the coastal ocean are often modeled by a nonlinear evolution equation of the Korteweg-de Vries type. Because these waves often propagate for long distances over several inertial periods, the effect of Earth's background rotation is potentially significant. The relevant extension of the Kortweg-de Vries is then the Ostrovsky equation, which for internal waves does not support a steady solitary wave solution. Recent studies using a combination of asymptotic theory, numerical simulations, and laboratory experiments have shown that the long time effect of rotation is the destruction of the initial internal solitary wave by the radiation of small-amplitude inertia-gravity waves, and the eventual emergence of a coherent, steadily propagating, nonlinear wave packet. However, in the ocean, internal solitary waves are often propagating over variable topography, and this alone can cause quite dramatic deformation and transformation of an internal solitary wave. Hence, the combined effects of background rotation and variable topography are examined. Then the Ostrovsky equation is replaced by a variable coefficient Ostrovsky equation whose coefficients depend explicitly on the spatial coordinate. Some numerical simulations of this equation, together with analogous simulations using the Massachusetts Institute of Technology General Circulation Model (MITgcm), for a certain cross section of the South China Sea are presented. These demonstrate that the combined effect of shoaling and rotation is to induce a secondary trailing wave packet, induced by enhanced radiation from the leading wave.