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首页> 外文期刊>Journal of Physical Oceanography >Randomness, Symmetry, and Scaling of Mesoscale Eddy Life Cycles
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Randomness, Symmetry, and Scaling of Mesoscale Eddy Life Cycles

机译：中尺度涡旋生命周期的随机性，对称性和缩放

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摘要

It is shown that the life cycles of nonlinear mesoscale eddies, a major component of low-frequency ocean physical variability, have a characteristic structure that differs fundamentally from that which would be expected on the basis of classical interpretations of ocean eddy evolution in terms of mean flow instability and equilibration followed by frictional, radiative, or barotropic decay, or of vortex merger dynamics in quasigeostrophic turbulent cascades. Further, it is found that these life cycles can be accurately modeled in terms of the large-amplitude excursions of a stochastic process. These conclusions, which apply in the corresponding global-mean context, follow from the examination of ensemble-mean and standard deviation time series of normalized eddy amplitude from an automated eddy identification and tracking analysis of a nearly two decade-merged satellite altimeter record of global sea surface height (SSH). The resulting series are found to have several striking and unexpected characteristics, including time-reversal symmetry and approximate self-similarity. Consistent results are obtained from a similar analysis of a 7-yr record of global SSH from a numerical ocean circulation model. The basic qualitative and quantitative statistical properties of these series can be remarkably well reproduced with an extremely simple stochastic model, in which the SSH increments between successive time points are random numbers, and the eddy life cycles are represented by excursions exceeding a given threshold. The stochastic model is found also to predict accurately the empirical autocorrelation structure of the underlying observed SSH field itself, when the autocorrelations are computed along long planetary (Rossby) wave characteristics.
机译：结果表明，非线性中尺度涡旋的生命周期是低频海洋物理可变性的主要组成部分，其特征结构与以经典均值对海洋涡旋演化的经典解释所期望的结构根本不同。准旋转的湍流叶栅中的流体不稳定性和平衡，然后是摩擦，辐射或正压衰减或涡旋合并动力学。此外，发现可以根据随机过程的大幅度偏移来精确地建模这些生命周期。这些结论适用于相应的全球平均背景，其依据是对近两年合并的全球卫星高度计记录进行自动涡流识别和跟踪分析的归一化涡旋振幅的集合均值和标准偏差时间序列的检验。海面高度（SSH）。发现所得的序列具有多个惊人的和出乎意料的特征，包括时间反转对称性和近似自相似性。从数值海洋环流模型对全球SSH的7年记录进行的类似分析获得了一致的结果。这些序列的基本定性和定量统计特性可以用一个非常简单的随机模型很好地重现，该模型中连续时间点之间的SSH增量是随机数，而涡旋生命周期由超出给定阈值的偏移表示。当沿着长行星（Rossby）波特征计算自相关时，还发现了随机模型还可以准确预测潜在的观测SSH场本身的经验自相关结构。

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  • 来源
    《Journal of Physical Oceanography》 |2014年第3期|1012-1029|共18页
  • 作者

    R. M. Samelson; M. G. Schlax; D. B. Chelton;

  • 作者单位

    College of Earth, Ocean, and Atmospheric Sciences, 104 CEOAS Admin.Bldg., Oregon State University, Corvallis, OR 97331-5503;

    College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon;

    College of Earth, Ocean, and Atmospheric Sciences, Oregon State University, Corvallis, Oregon;

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