Energetics of wind-induced turbulent mixing in the ocean
Energetics of wind-induced turbulent mixing in the ocean
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DOI：
10.1007/s10872-008-0010-8
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发表时间：
2008-02
影响因子：
2.3
通讯作者：
Michio Watanabe;T. Hibiya
中科院分区：
文献类型：
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作者：
Michio Watanabe;T. Hibiya
全球海洋翻转环流的模式和大小被认为强烈地受控于1000米以下的日扩散系数的分布。虽然风应力波动是昼夜混合过程的主要能源之一，但风致昼夜扩散系数的全球分布仍然是不确定的。人们认为，中高纬度风应力起伏产生的内波沿赤道传播，直至其频率是局地惯性频率的两倍，并通过参数亚谐不稳定而破裂，引起昼夜混合。为了验证所提出的情景，我们使用一个垂直二维原始方程模式来检验由风应力波动引起的“混合热点”的空间分布。结果表明，输入海洋内部的风能大部分在强风区表层1000m深度内耗散，低纬地区的耗散率很小。因此，向1000米以下的昼夜混合过程提供的能量达不到维持全球海洋翻转环流所需的水平。
The pattern and magnitude of the global ocean overturning circulation is believed to be strongly controlled by the distribution of diapycnal diffusivity below 1000 m depth. Although wind stress fluctuation is a candidate for the major energy sources of diapycnal mixing processes, the global distribution of wind-induced diapycnal diffusivity is still uncertain. It has been believed that internal waves generated by wind stress fluctuations at middle and high latitudes propagate equatorward until their frequency is twice the local inertial frequency and break down via parametric subharmonic instabilities, causing diapycnal mixing. In order to check the proposed scenario, we use a vertically two-dimensional primitive equation model to examine the spatial distribution of “mixing hotspots” caused by wind stress fluctuations. It is shown that most of the wind-induced energy fed into the ocean interior is dissipated within the top 1000 m depth in the wind-forced area and the energy dissipation rate at low latitudes is very small. Consequently, the energy supplied to diapycnal mixing processes below 1000 m depth falls short of the level required to sustain the global ocean overturning circulation.