Chaotic mixing of tracer and vorticity by modulated travelling Rossby waves
Chaotic mixing of tracer and vorticity by modulated travelling Rossby waves
复制标题
调制罗斯贝行波的示踪剂和涡度的混沌混合
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发表时间：
1991
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通讯作者：
R. Pierrehumbert
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作者：
R. Pierrehumbert
摘要通过二维时间起伏的大尺度流动，我们考虑了被动示踪和涡度的混合。在分析这个问题时，我们使用了源于粒子轨迹中哈密顿混沌特性的现代发展；这些发展通常被归入“混沌平流”或“拉格朗日湍流”的标题下。在正压Rossby波的被动示踪混合的背景下，回顾了这种混合的显著性质，以及用来分析它的数学方法。然后，我们开始描述混合的更微妙的方面。结果表明，混沌平流产生非局域混合，而非局域混合不能用涡动扩散系数表示。此外，示踪场的功率谱被发现是在短波处的k−L--与均匀的、各向同性的二维湍流的混合完全相同--尽管现在的物理情况非常不同。我们已经提出了两个独立的论点来解释这一点。
Abstract We consider the mixing of passive tracers and vorticity by temporally fluctuating large scale flows in two dimensions. In analyzing this problem, we employ modern developments stemming from properties of Hamiltonian chaos in the particle trajectories; these developments generally come under the heading “chaotic advection” or “Lagrangian turbulence.” A review of the salient properties of this kind of mixing, and the mathematics used to analyze it, is presented in the context of passive tracer mixing by a vacillating barotropic Rossby wave. We then take up the characterization of subtler aspects of the mixing. It is shown the chaotic advection produces very nonlocal mixing which cannot be represented by eddy diffusivity. Also, the power spectrum of the tracer field is found to be k − l at shortwaves—precisely as for mixing by homogeneous, isotropic two dimensional turbulence,—even though the physics of the present case is very different. We have produced two independent arguments accounting for thi...