Approximation of wave action conservation in vertically sheared mean flows
Approximation of wave action conservation in vertically sheared mean flows
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DOI：
10.1016/j.ocemod.2019.101460
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发表时间：
2019-11
期刊：
影响因子：
3.2
通讯作者：
Saeideh Banihashemi;J. Kirby
中科院分区：
文献类型：
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作者：
Saeideh Banihashemi;J. Kirby
我们利用Kirby&Chen(1989)的S弱切变水流摄动解的推广，导出了波作用密度和作用通量的渐近表达式，其中考虑了基本水流的Froude数F=U/g h=O(1)，但具有弱的垂直切变。通过与恒切变流的解析结果、具有强垂直切变的浮力落潮羽流和风生流的数值计算结果的比较，确定了作用密度和通量表达式的精度。我们将我们的结果与Quinn等人(2017)最近的工作进行了比较，并发现了先前工作中尚未解决的差异。我们根据峰值频率和方向上的条件，使用泰勒级数展开，提出了在耦合波/环流模式中有效实施所需扩展的附加建议。这些结果将Banihashemi等人(2017)以前的工作推广到两个水平维度的运动，并涵盖了波作用的确定。
We develop asymptotic expressions for wave action density and action flux, using an extension of Kirby & Chen (1989)’s perturbation solution for weakly-sheared currents allowing for a basic flow with Froude number F= U∕ g h= O (1) but with weak vertical shear. The accuracy of the expressions for action density and flux is established by comparison to analytic results for a current with constant shear, and to numerical results for a field case involving a buoyant ebb-tidal plume with strong vertical shear and for a case involving a numerically determined profile for a wind-driven current. We compare our results to those from recent work of Quinn et al.(2017), and find unresolved discrepancies in that prior work. We provide additional suggestions for efficiently implementing the required extensions in coupled wave/circulation models using a Taylor series expansion based on conditions at peak frequency and direction. These results generalize the previous work of Banihashemi et al.(2017) to motions in two horizontal dimensions, and cover the determination of the wave action.