Resonant Generation and Energetics of Wind-Forced Near-Inertial Motions in a Geostrophic Flow
Resonant Generation and Energetics of Wind-Forced Near-Inertial Motions in a Geostrophic Flow
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DOI：
10.1175/jpo-d-14-0168.1
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发表时间：
2015-01
影响因子：
3.5
通讯作者：
D. Whitt;L. Thomas
中科院分区：
文献类型：
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作者：
D. Whitt;L. Thomas
本文利用平板混合层模式和二维数值模拟研究了振荡风强迫下单向横向切变地转流近惯性振荡的产生和能量学。海流zg的垂直涡度改变了有效科里奥利频率fffififififififififififififififififififi 1 zg/f p，它相当于当地的共振强迫频率。此外，共振振荡速度响应是椭圆形的，而不是圆形的，因为振荡周期性地通过剪切产生与地转流交换能量。有了阻尼，这种能量交换就成为永久性的，但其大小和符号强烈地依赖于振荡风矢量相对于地转流的角度。然而，对于由各向同性风向分布强迫的海流，在所有风向角上平均的响应导致从地转流中提取净能量，该净能量随着风对惯性力的作用而缩放。
A slab mixed layer model and two-dimensional numerical simulations are used to study the generation and energetics of near-inertial oscillations in a unidirectional, laterally sheared geostrophic current forced by oscillatory winds. The vertical vorticity of the current zg modifies the effective Coriolis frequency f ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi1zg/f p , which is equivalent to the local resonant forcing frequency. In addition, the resonant oscillatory velocity response is elliptical, not circular, because the oscillation periodically exchanges energy with the geostrophic flow via shear production. With damping, this energy exchange becomes permanent, but its magnitude and sign depend strongly on the angle of the oscillatory wind vector relative to the geostrophic flow. However, for a current forced by an isotropic distribution of wind directions, the response averaged over all wind angles results in a net extraction of energy from the geostrophic flow that scales as the wind work on the inertial