Direct breaking of large-amplitude internal waves in the Urup Strait
Direct breaking of large-amplitude internal waves in the Urup Strait
复制标题
乌鲁普海峡大振幅内波直接破碎
DOI：
10.1016/j.pocean.2014.04.014
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发表时间：
2014
影响因子：
4.1
通讯作者：
J. Nishioka and Y. N. Volkov
中科院分区：
文献类型：
--
作者：
Itoh;S;Y. Tanaka;S. Osafune;I. Yasuda;M. Yagi;H Kaneko;S. Konda;J. Nishioka and Y. N. Volkov
对千岛海峡之一乌鲁普海峡的观测和模式数据进行了分析，重点是驱动极强垂直混合的过程。超过1天的观测结果显示，在太平洋一侧的窗台的乌鲁普海峡的大振幅内波（LAIW）的产生，其特征是由一个强大的窗台外流造成的潜在密度面的抑郁症。当LAIW发展时，26.7σθ的势密度面向下压低了300 m以上，400 m厚的26.6-26.7σθ层内垂直混合明显增强，层平均（最大）能量耗散率和垂直扩散率为1.2 × 10−6（7.9 × 10− 6 W kg−1）和4.0 × 10−1（2.8 m2 s −1）。千岛海峡昼夜正压潮驱动的三维模式模拟再现以及观察到的功能相关的生成LAIWs的乌鲁普海峡。在乌鲁普海峡的LAIWs的结构和生成模式是一致的，在夏威夷海脊和吕宋海峡观察到的被捕的背风波，虽然在乌鲁普海峡的窗台顶部的深度是浅得多。结果表明，周日频率的正压潮能通过底坎顶部超临界流速地形捕获波的激发转化为LAIWs，正是这些地形捕获波导致了千岛海峡浅水区底坎侧翼的强烈混合。
Observations and model data have been analyzed for the Urup Strait, one of the Kuril Straits, focusing on processes driving the extremely strong vertical mixing. Observations over 1 day on the Pacific side of the sill of the Urup Strait show the generation of a large-amplitude internal wave (LAIW), characterized by the depression of potential density surfaces caused by a strong off-sill flow. When the LAIW developed, the potential density surface of 26.7σθwas depressed downward by more than 300 m, and vertical mixing was markedly elevated within the 400-m-thick layer 26.6–26.7σθ, with a layer-mean (maximum) energy dissipation rate and vertical diffusivity of 1.2 × 10−6(7.9 × 10−6W kg−1) and 4.0 × 10−1(2.8 m2s−1), respectively. A three-dimensional model simulation of the Kuril Straits driven by the diurnal barotropic tide reproduces well the observed features relevant to the generation of LAIWs in and around the Urup Strait. The structure and generation pattern of LAIWs in the Urup Strait are consistent with those of the arrested lee waves observed in the Hawaiian ridge and Luzon Strait, although the depth at the top of the sill is far shallower in the Urup Strait. It is suggested that barotropic tidal energy with diurnal frequency is converted into LAIWs through the excitation of topographically trapped waves with hydraulically supercritical velocity near the sill top, and it is these waves that are responsible for the extremely strong mixing on the sill-flanks of the shallow Kuril Straits.