Temporal variations in internal tide multimodal structure on the continental shelf, South China Sea

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• 作者：Dalu Gao 高大鲁 ; Guangzhen Jin 靳光震…
• 关键词：internal tides ; South China Sea ; multimodal structure ; temporal variation
• 刊名：Chinese Journal of Oceanology and Limnology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：35
• 期：1
• 页码：70-78
• 全文大小：
• 刊物主题：Oceanography;
• 出版者：Science Press
• ISSN：1993-5005
• 卷排序：35

文摘

Temporal variations in multimodal structures of diurnal (D₁) and semidiurnal (D₂) internal tides were investigated on the continental slope of the Dongsha Plateau, based on 2-month moored acoustic Doppler current profiler observations. Harmonic analysis indicated that the D₁ components (K₁ and O₁) dominated the internal tide field. The vertical structure of the K₁ constituent presented a first-mode structure while the M₂ constituent seemed to exhibit a high-mode structure. Amplitude spectra analysis of the current data revealed differences in baroclinic current amplitudes between different water depths. Temporal variations in modal structures ware analyzed, based on the D₁ and D₂ baroclinic tides extracted from the baroclinic velocity field with band-pass filters. Analysis showed that the magnitude of the D₁ internal tide current was much larger than the D₂ current, and temporal variations in the modal structure of the D₁ internal tide occurred on an approximately fortnightly cycle. The EOF analyses revealed temporal transformation of multimodal structures for D₁ and D₂ internal tides. The enhancement of the D 1 internal tide was mainly due to the superposition of K₁ and O₁, according to the temporal variation of coherent kinetic energy.