On generation and evolution of seaward propagating internal solitary waves in the northwestern South China Sea
On generation and evolution of seaward propagating internal solitary waves in the northwestern South China Sea
复制标题
南海西北部向海传播内孤立波的产生与演化
DOI：
10.1016/j.cnsns.2015.08.013
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发表时间：
2016-03
影响因子：
3.9
通讯作者：
Cai Shuqun
中科院分区：
文献类型：
--
作者：
Xu Jiexin;Chen Zhiwu;Xie Jieshuo;Cai Shuqun
利用完全非线性、非静力、三维马萨诸塞州理工学院大气环流模式（MITgcm）研究了南海西北部卫星云图上向海传播的内孤立波（ISW）的产生和演变。三维模拟结果与卫星云图结果吻合较好，表明海南岛南部弧形陆坡与正压潮流的相互作用可能产生了向海传播的ISW。虽然潮流基本上是东西向的，但潮流流经不同形状的海岸线的斜坡时会产生不同类型的内波。在海岸线平直的斜坡上，只产生微弱的内潮;在海岸线向海凹陷的斜坡上，产生大幅度的内孔，由于弧形大陆坡的凹陷等深线倾向于集中斜压潮汐能并将其输送到内孔，内孔在其远离斜坡传播期间可有效地分解成一列按等级排序的ISW;而在海岸线向海凸起的斜坡上，没有产生明显的内潮。斜坡上的内波是由混合背风波机制产生的。此外，还讨论了三维模型、陆坡曲率、层结、旋转和潮汐力等因素对ISW产生的影响。结果表明，二维模式的ISW幅值和相速度均小于三维模式，三维模式在模拟潮流与三维弯曲陆坡相互作用产生的ISW方面优于二维模式;较弱的层结和旋转都抑制了ISW的产生，K1潮汐谐波产生的ISW波峰线宽度大于M2潮汐谐波。
In this paper, the generation and evolution of seaward propagating internal solitary waves (ISWs) detected by satellite image in the northwestern South China Sea (SCS) are investigated by a fully nonlinear, non-hydrostatic, three-dimensional Massachusetts Institute of Technology general circulation model (MITgcm). The three-dimensional (3D) modeled ISWs agree favorably with those by satellite image, indicating that the observed seaward propagating ISWs may be generated by the interaction of barotropic tidal flow with the arc-like continental slope south of Hainan Island. Though the tidal current is basically in east–west direction, different types of internal waves are generated by tidal currents flowing over the slopes with different shaped shorelines. Over the slope where the shoreline is straight, only weak internal tides are generated; over the slope where the shoreline is seaward concave, large-amplitude internal bores are generated, and since the concave isobaths of the arc-like continental slope tend to focus the baroclinic tidal energy which is conveyed to the internal bores, the internal bores can efficiently disintegrate into a train of rank-ordered ISWs during their propagation away from the slope; while over the slope where the shoreline is seaward convex, no distinct internal tides are generated. It is also implied that the internal waves over the slope are generated due to mixed lee wave mechanism. Furthermore, the effects of 3D model, continental slope curvature, stratification, rotation and tidal forcing on the generation of ISWs are discussed, respectively. It is shown that, the amplitude and phase speed of ISWs derived from a two-dimensional (2D) model are smaller than those from the 3D one, and the 3D model has an advantage over 2D one in simulating the ISWs generated by the interaction between tidal currents and 3D curved continental slope; the reduced continental slope curvature hinders the extension of ISW crestline; both weaker stratification and rotation suppress the generation of ISWs; and the width of ISW crestline generated by K1tidal harmonic is longer than that by M2tidal harmonic.
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