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首页> 外文期刊>Journal of Physical Oceanography >Energy Sinks for Lee Waves in Shear Flow
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Energy Sinks for Lee Waves in Shear Flow

机译：剪切流中的李波能量沉

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Microstructure measurements in Drake Passage and on the flanks of Kerguelen Plateau find turbulent dissipation rates epsilon on average factors of 2-3 smaller than linear lee-wave generation predictions, as well as a factor of 3 smaller than the predictions of a well-established parameterization based on finescale shear and strain. Here, the possibility that these discrepancies are a result of conservation of wave action E/omega(L) = E/|kU| is explored. Conservation of wave action will transfer a fraction of the lee-wave radiation back to the mean flow if the waves encounter weakening currents U, where the intrinsic or Lagrangian frequency omega(L) = |kU| (_) |f| and k the along-stream horizontal wavenumber, where kU equivalent to k center dot V. The dissipative fraction of power that is lost to turbulence depends on the Doppler shift of the intrinsic frequency between generation and breaking, hence on the topographic height spectrum and bandwidth N/f. The partition between dissipation and loss to the mean flow is quantified for typical topographic height spectral shapes and N/f ratios found in the abyssal ocean under the assumption that blocking is local in wavenumber. Although some fraction of lee-wave generation is always dissipated in a rotating fluid, lee waves are not as large a sink for balanced energy or as large a source for turbulence as previously suggested. The dissipative fraction is 0.44-0.56 for topographic spectral slopes and buoyancy frequencies typical of the deep Southern Ocean, insensitive to flow speed U and topographic splitting. Lee waves are also an important mechanism for redistributing balanced energy within their generating bottom current.
机译：在德雷克海峡和克格伦高原的侧翼进行的微结构测量发现，湍流耗散率ε的平均因子比线性背风波产生的预测值小2-3，并且比公认的参数化预测的值小3基于细尺度的剪切和应变。在这里，这些差异可能是由于波动作用守恒E / omega（L）= E / | kU |的结果。被探索。如果波浪遇到弱化电流U，则守恒的波浪作用将把部分回风辐射转换回平均流，在此处，固有或拉格朗日频率omega（L）= | kU |。 （_）| f | k为沿流的水平波数，其中kU等于k中心点V。湍流损失的功率耗散部分取决于生成和破裂之间固有频率的多普勒频移，因此取决于地形高度谱和带宽N / f。对于典型的地形高度频谱形状和在深海中发现的N / f比，在阻塞位于波数局部的假设下，量化了耗散与平均流量损失之间的分配。尽管回风的某些部分总是散布在旋转的流体中，但是回风并没有像以前建议的那样大，可以吸收平衡的能量，也不能像湍流那样大。对于南部深海典型的地形频谱斜率和浮力频率，耗散率为0.44-0.56，对流速U和地形分裂不敏感。 Lee波还是在其产生的底部电流内重新分配平衡能量的重要机制。

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