On the generation and evolution of internal solitary waves in the northwestern South China Sea
On the generation and evolution of internal solitary waves in the northwestern South China Sea
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DOI：
10.1016/j.ocemod.2011.08.005
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发表时间：
2011
期刊：
影响因子：
3.2
通讯作者：
Delei Li;Xue'en Chen;A. Liu
中科院分区：
文献类型：
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作者：
Delei Li;Xue'en Chen;A. Liu
近年来，在南海西北部的遥感影像上观测到了内孤立波。仔细研究这些ISWs的波峰，认为它们是由于潮汐-地形相互作用而局部产生的。为了证实这一假设，应用麻省理工学院的二维、全非线性、非流体静力环流模型（MITgcm）研究了南海西北部ISWs的产生过程和机制。通过一系列数值模拟，探讨了海底地形、潮汐强迫强度、分层和不同潮汐谐波对ISW产生的影响。分析认为，浅滩西侧的isw是在浅滩上的潮流由退潮向涨潮转变时产生的，而浅滩东侧的isw则是在浅滩上退潮开始时产生的。弗劳德数和坡度参数的分析表明，该地区isw的形成受混合背风波的影响，而不是斜压潮或非定常背风波的影响。对这些isw的仔细观察表明，不同的内波模态在断层周围存在叠加，发育良好的第一和第二isw在离断层较远的地方明显。模型域中有三种技能，从西到东分别标记为技能a、b和c。数值实验表明，在这些层位以西的isw是由层位b和层位c产生的，而层位a则加剧了内波的非线性并产生了更高的内波模态。这些技能以东的isw仅由技能c生成。
Recently, internal solitary waves (ISWs) were observed from remote sensing images of the northwestern South China Sea (SCS). Scrutinizing the crests of these ISWs, it was suggested that they were generated locally as a result of tide–topography interaction. To confirm this assumption, a 2-D, fully nonlinear, non-hydrostatic Massachusetts Institute of Technology general circulation model (MITgcm) was applied to investigate the generation process and mechanism of ISWs in the northwestern SCS. A series of numerical simulations were carried out to explore the influences from the bottom topography, strength of tidal forcing, stratification and different tidal harmonics on ISW generation. It can be concluded that the ISWs to west of the sills were generated when the tidal flow over the sills changed from an ebb tide to a flood tide, while the generation of those to the east of the sills was associated with the start of the ebb tide. Analyses of the Froude number and slope parameter, which govern generation regimes, indicate that the generation of ISWs in this area is subject to mixed lee waves rather than to a baroclinic tide regime or unsteady lee wave regime. Scrutiny of these ISWs reveals that the superposition of different internal wave modes exists around the sills, and well-developed first and second ISWs are pronounced further away from the sills. There are three sills in the model domain, labeled sills a, b and c from the west to the east, respectively. Numerical experiments suggest that ISWs to the west of these sills are generated by sills b and c, while sill a intensifies the nonlinearity of the internal waves and generates higher internal wave modes. ISWs to the east of these sills are generated by sill c only.