Thickness-Weighted Mean Theory for the Effect of Surface Gravity Waves on Mean Flows in the Upper Ocean
Thickness-Weighted Mean Theory for the Effect of Surface Gravity Waves on Mean Flows in the Upper Ocean
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DOI：
10.1175/jpo-d-11-095.1
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发表时间：
2012-05
影响因子：
3.5
通讯作者：
H. Aiki;R. Greatbatch
中科院分区：
文献类型：
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作者：
H. Aiki;R. Greatbatch
利用厚度加权平均（TWM）理论，在垂直拉格朗日坐标系和水平欧拉坐标系下研究了表面重力波对上层海洋平均流的残余效应。导出了体积、动量和能量守恒的深度相关方程。这些方程允许(i)有限振幅流体运动，（ii）水流的水平发散，以及（iii）海面运动和粘性边界条件的简明处理。在稳定、单色波和均匀湍流黏度的假设下，利用twm动量方程来说明压力和黏度诱导的表面动量通量，这在以往的经典ekman螺旋问题的波动修正研究中是隐含的。,其thesurfacemomentumfluxassociatedwiththeso-calledvirtualwavestressofLonguetHiggins TheTWMapproach澄清。总的来说，twm框架可以被视为Pierson的三维拉格朗日平均框架的替代方案。此外，在大尺度环流模式中，可以使用TWM框架来考虑表面波的残余效应。在以适合平流示踪剂的TWM速度作为速度变量的特定模型中，应修改湍流粘度项，使粘度仅作用于欧拉平均速度。
The residual effect of surface gravity waves on mean flows in the upper ocean is investigated using thicknessweighted mean (TWM) theory applied in a vertically Lagrangian and horizontally Eulerian coordinate system. Depth-dependent equations for the conservation of volume, momentum, and energy are derived. These equationsallowfor(i)finiteamplitudefluidmotions,(ii)thehorizontaldivergenceofcurrents,and(iii)aconcise treatment of both kinematic and viscous boundary conditions at the sea surface. Under the assumptions of steadyandmonochromaticwaves anda uniformturbulentviscosity,theTWMmomentum equationsare used to illustrate the pressure- and viscosity-induced momentum fluxes through the surface, which are implicit in previousstudiesofthewave-inducedmodification oftheclassicalEkmanspiralproblem. TheTWMapproach clarifies,inparticular,thesurfacemomentumfluxassociatedwiththeso-calledvirtualwavestressofLonguetHiggins.Overall,theTWMframeworkcanberegardedasanalternativetothethree-dimensionalLagrangian mean framework of Pierson. Moreover, the TWM framework can be used to include the residual effect of surface waves in large-scale circulation models. In specific models that carry the TWM velocity appropriate for advecting tracers as their velocity variable, the turbulent viscosity term should be modified so that the viscosity acts only on the Eulerian mean velocity.