南海东北部陆架波折处潮—地作用激发非线性内波的数值模拟

Numerical modeling on the nonlinear internal wave generation by the tide-shelf break interaction at the Northeastern South China Sea

南海东北部陆架波折处是大振幅内孤立波的频发地带。普遍的观点认为,这些内孤立波主要源自于吕宋海峡处潮流与海脊的相互作用;而对局地潮流-陆架波折相互作用的生成过程了解较少。本文通过一个二维非静力近似海洋数值模式,模拟了南海东北部陆架波折处潮流-地形相互作用激发内波及内波的演化过程,探讨了潮流周期、跃层深度对内波生成过程的影响。研究表明,潮流与地形相互作用能够激发向岸传播的内孤立子波列,证实了该海区内孤立波局地生成的可能性,但是相比于从吕宋海峡处传入的大振幅内孤立波,局地生成的内孤立波振幅要小得多。

Large amplitude Internal Solitary Wave （ISW） is frequently observed at the Northeastern South China Sea. Most research focused on the generation of ISW from Luzon strait and its propagation towards the continental shelf. Local generation of such waves by the tide-shelf break interaction has been less studied. Based on a nonhydrostatic numerical model, the generation and propagation of ISW by the tide-shelf break interaction at the Northeastern South China Sea were studied. It revealed that the interaction of tidal current and the bottom topography can generation onshore propagated ISW trains, proved the possibility of the local generation of ISW. Compared with the propagated ISW from Luzon straits, the local generation ISW has smaller amplitude. The amplitude of the local generated ISW depends on the tidal current period and pycnocline depth.