Numerical study of K1 internal tides in the Kuril straits
Numerical study of K1 internal tides in the Kuril straits
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DOI：
10.1029/2009jc005903
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发表时间：
2010-09
影响因子：
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通讯作者：
Yuki Tanaka;T. Hibiya;Y. Niwa;Nobuyuki Iwamae
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文献类型：
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作者：
Yuki Tanaka;T. Hibiya;Y. Niwa;Nobuyuki Iwamae
[1]在千岛海峡，由潮汐引起的强烈的贯叶混合被认为是控制北太平洋水团形成的重要过程之一。为了使一个明确的量化在千岛海峡的diapycnal扩散，我们驱动一个三维的数值模型，并检查的产生，传播和耗散功能的内波，发挥了重要作用，从主要的K1正压潮的能量传递到diapycnal混合过程。结果表明，K_1正压潮减去内波能量后的大部分能量都耗散在千岛海峡内，使得局部耗散效率为0.8-1.0，约为以前所用数值的3倍。这是因为K1潮汐频率在该区域是亚惯性的，因此大量的K1潮汐能被馈送到海岸被困波（CTW）中，这些被困波停留在每个岛屿周围而不传播离开海峡; CTW在洋底附近引起强烈的速度切变，引起底部限制的强烈混合，垂直衰减尺度为200米，不到以前使用的值的一半，尽管仍然存在由所采用的粘度和扩散率的参数化引起的一些不确定性。千岛海峡的平均穿透扩散率为25 × 10−4 m2 s−1，约为先前估计值的三倍，但仍比现有海洋环流模式中对千岛海峡的假设低一个数量级。
[1] Tide-induced strong diapycnal mixing in the Kuril straits is thought to be one of the essential processes controlling water mass formation in the North Pacific. In order to make a definite quantification of diapycnal diffusivity in the Kuril straits, we drive a three-dimensional numerical model and examine the generation, propagation, and dissipation features of internal waves which play an essential role in transferring energy from the predominant K1 barotropic tide to diapycnal mixing processes. It is shown that most of the internal wave energy subtracted from the K1 barotropic tide is dissipated within the Kuril straits such that the local dissipation efficiency becomes 0.8–1.0, about three times the value previously employed. This is because the K1 tidal frequency is subinertial in this area so that significant amount of K1 tidal energy is fed into coastal trapped waves (CTWs) which stay around each island without propagating away from the straits; CTWs induce strong velocity shear near the ocean bottom causing bottom-confined intense mixing with a vertical decay scale ∼200 m, less than half the value previously employed, although there remains some uncertainties resulting from the employed parameterizations of viscosity and diffusivity. The average diapycnal diffusivity in the Kuril straits becomes ∼25 × 10−4 m2 s−1, about three times the value previously estimated, although it is still an order of magnitude less than assumed for the Kuril straits in the existing ocean general circulation models.