https://scholars.lib.ntu.edu.tw/handle/123456789/606386
標題: | Long-Term Observations of Shoaling Internal Solitary Waves in the Northern South China Sea | 作者: | Chang M.-H Lien R.-C Lamb K.G MING-HUEI CHANG |
關鍵字: | convective breaking;internal solitary waves;marginal instability;South China Sea;trapped core;turbulent mixing;bottom topography;continental slope;detection method;dispersion;instability;observational method;solitary wave;stratification;Pacific Ocean | 公開日期: | 2021 | 卷: | 126 | 期: | 10 | 來源出版物: | Journal of Geophysical Research: Oceans | 摘要: | Shoaling internal solitary waves (ISWs) were observed at three mooring sites on the upper continental slope in the northern South China Sea over a period of 5–11?months at water depths of 600, 430, and 350?m. Their properties exhibit a fortnightly variation because of their origination from internal tides. ISW amplitudes, current speeds, and propagation speeds are greater and wave widths narrower in summer than in winter, consistent with the effect of increased stratification in summer, as confirmed by Dubreil-Jacotin-Long (DJL) solutions. As ISWs propagate up the slope, the differential response of current and propagation speeds to bottom topography provides an opportunity for convective breaking of ISWs. Convective breaking occurs mostly between 430 and 600-m depths and exhibits a marginal convective instability status such that (a) the maximum current speed remains nearly equal to the propagation speed and (b) for large-amplitude waves the current speed and propagation speed decrease at nearly the same rate between 600 and 430-m depths. The marginal convective instability occurs because ISWs adjust gradually to the gently sloping bottom and preserve their structural integrity after the onset of breaking. Vertical velocity variances behind the leading ISWs, which serve as a surrogate for the number of trailing waves, increase when ISWs reach the convective breaking limit, suggesting that convective breaking may accelerate the fission process in leading ISWs or that convective breaking is accompanied by an enhanced nonlinear dispersion of waves trailing ISWs generated by internal tides. ? 2021. The Authors. |
URI: | https://www.scopus.com/inward/record.uri?eid=2-s2.0-85118376318&doi=10.1029%2f2020JC017129&partnerID=40&md5=e97194dfffc17105b89c9786276d8749 https://scholars.lib.ntu.edu.tw/handle/123456789/606386 |
ISSN: | 21699275 | DOI: | 10.1029/2020JC017129 |
顯示於: | 海洋研究所 |
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