Latitudinal dependence of diapycnal diffusivity in the thermocline estimated using a finescale parameterization
Latitudinal dependence of diapycnal diffusivity in the thermocline estimated using a finescale parameterization
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DOI：
10.1029/2003gl017998
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发表时间：
2004-01
影响因子：
5.2
通讯作者：
T. Hibiya;M. Nagasawa
中科院分区：
文献类型：
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作者：
T. Hibiya;M. Nagasawa
通过将消耗性电流剖面仪测量的水平速度的细尺度垂直切变纳入Gregg[1989]提出的经验公式中，可以得到北太平洋内部大面积温跃层内横旋扩散系数的空间分布。结果清楚地表明，北太平洋的潜流扩散率在很大程度上取决于纬度。例如，夏威夷海岭和伊津-小笠原海岭附近的估计潜流扩散系数超过10−4 m2 s−1，而阿留申海岭和皇帝海山附近的估计潜流扩散系数约为0.1 × 10−4 m2 s−1，尽管在所有这些突出的地形特征中可用的半日内部潮汐能相似。观测结果与数值预测一致，即内部潮汐能降至耗散尺度的级联主要是参数次谐波不稳定，预计只发生在30°N以下。
The spatial distribution of diapycnal diffusivity in the thermocline over a large area in the interior of the North Pacific is obtained by incorporating the finescale vertical shear of horizontal velocity measured by expendable current profilers into the empirical formula proposed by Gregg [1989] . It is clearly shown that diapycnal diffusivity in the North Pacific strongly depends on the latitude. For example, the estimated diapycnal diffusivities near the Hawaiian Ridge and the Izu‐Ogasawara Ridge exceed 10−4 m2 s−1, whereas those near the Aleutian Ridge and the Emperor Seamounts are of the order of 0.1 × 10−4 m2 s−1, even though the available semidiurnal internal tidal energy is similar among all of these prominent topographic features. The observed results are consistent with the numerical prediction that the cascade of internal tidal energy down to dissipation scales is dominated by parametric subharmonic instability which is expected to occur only below 30°N.