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首页> 外文期刊>Journal of Physical Oceanography >Global Patterns of Mesoscale Eddy Properties and Diffusivities
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Global Patterns of Mesoscale Eddy Properties and Diffusivities

机译：中尺度涡特性和扩散率的整体模式

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摘要

Mesoscale eddies play a major role in the transport of tracers in the ocean. Focusing on a sector in the east Pacific, the authors present estimates of eddy diffusivities derived from kinematic tracer simulations using satellite-observed velocity fields. Meridional diffusivities are diagnosed, and how they are related to eddy properties through the mixing length formulation of Ferrari and Nikurashin, which accounts for the suppression of diffusivity due to eddy propagation relative to the mean flow, is shown. The uniqueness of this study is that, through systematically varying the zonal-mean flow, a hypothetical "unsuppressed" diffusivity is diagnosed. At a given latitude, the unsuppressed diffusivity occurs when the zonal-mean flow equals the eddy phase speed. This provides an independent estimate of eddy phase propagation, which agrees well with theoretical arguments. It is also shown that the unsuppressed diffusivity is predicted very well by classical mixing length theory, that is, that it is proportional to the rms eddy velocity times the observed eddy size, with a spatially constant mixing efficiency of 0.35. Then, the suppression factor is estimated and it is shown that it too can be understood quantitatively in terms of easily observed mean flow properties. The authors then extrapolate from these sector experiments to the global scale, making predictions for the global surface eddy diffusivity. Together with a prognostic equation for eddy kinetic energy and a theory explaining observed eddy sizes, these concepts could potentially be used in a closure for eddy diffusivities in coarse-resolution ocean climate models.
机译：中尺度涡旋在海洋示踪剂的运输中起主要作用。作者着眼于东太平洋的一个区域，提出了涡旋扩散率的估计值，该估计值是使用卫星观测的速度场从运动学示踪剂模拟得出的。诊断了子午线扩散率，并显示了通过法拉利和尼古拉辛的混合长度公式，它们与涡流特性之间的关系，该公式说明了相对于平均流量的涡流传播所引起的扩散率的抑制。这项研究的独特之处在于，通过系统地改变区域平均流量，可以诊断出一种假设的“未抑制”扩散性。在给定的纬度下，当纬向平均流量等于涡流相速度时，就会出现不可抑制的扩散率。这提供了涡流相位传播的独立估计，这与理论观点非常吻合。还表明，通过经典混合长度理论可以很好地预测未抑制的扩散率，也就是说，它与均方根涡流速度乘以观察到的涡流大小成正比，而空间恒定的混合效率为0.35。然后，对抑制因子进行了估算，结果表明，根据容易观察到的平均流量特性，也可以定量地理解抑制因子。然后，作者从这些部门实验中推断出全球范围，从而预测了全球表面涡流扩散率。结合涡动能的预后方程式和解释观测到的涡旋大小的理论，这些概念可潜在地用于封闭粗分辨率海洋气候模型中的涡旋扩散率。

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  • 来源
    《Journal of Physical Oceanography》 |2014年第3期|1030-1046|共17页
  • 作者

    Andreas Klocker; Ryan Abernathey;

  • 作者单位

    Research School of Earth Sciences, Australian National University, Acton, Australian Capital Territory, and ARC Centre of Excellence for Climate System Science, Sydney, New South Wales, Australia,Institute of Marine and Antarctic Studies, University of Tasmania, 20 Castray Esplanade, Battery Point, TAS 7004, Australia;

    Department of Earth and Environmental Sciences, Columbia University, New York, New York;

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