scholarly journals Low-Frequency Variability of Monsoon-Driven Circulation with Application to the South China Sea

2015 ◽  
Vol 45 (6) ◽  
pp. 1632-1650 ◽  
Author(s):  
Haiyuan Yang ◽  
Lixin Wu ◽  
Sun Shantong ◽  
Chen Zhaohui
Keyword(s):  
South China Sea ◽  
Ocean Circulation ◽  
South China ◽  
Low Frequency ◽  
The South China Sea ◽  
Upper Ocean ◽  
China Sea ◽  
Low Frequency Variability ◽  
Gyre System ◽  
Double Gyre

AbstractThe interannual variability of the upper-ocean circulation forced by seasonally varying monsoonal wind is investigated in a two-layer quasigeostrophic (QG) model, with the aim to understand the low-frequency variability of the South China Sea (SCS) circulation. It is demonstrated that the seasonally varying monsoonal wind can force the upper-ocean circulation with significant internal variability, which is mainly associated with the intrinsic nonlinear dynamics of the summer double-gyre system. This arises from the fact that the intrinsic variability, characterized by the Rossby wave adjustment in the winter single-gyre system, is much weaker than that in the summer double-gyre system driven by the intergyre eddy potential vorticity flux through barotropic instability.

Disintegration of the K1 internal tide in the South China Sea due to parametric subharmonic instability

2021 ◽  
Author(s):  
Kun Liu ◽  
Zhongxiang Zhao
Keyword(s):  
South China Sea ◽  
South China ◽  
Internal Tide ◽  
The South China Sea ◽  
Internal Tides ◽  
Upper Ocean ◽  
The South ◽  
China Sea ◽  
Parametric Subharmonic Instability ◽  
Critical Latitude

<p>The disintegration of the equatorward-propagating K<sub>1</sub> internal tide in the South China Sea (SCS) by parametric subharmonic instability (PSI) at its critical latitude of 14.52ºN is investigated numerically. The multiple-source generation and long-range propagation of K<sub>1</sub> internal tides are successfully reproduced. Using equilibrium analysis, the internal wave field near the critical latitude is found to experience two quasi-steady states, between which the subharmonic waves develop constantly. The simulated subharmonic waves agree well with classic PSI theoretical prediction. The PSI-induced near-inertial waves are of half the K<sub>1</sub> frequency and dominantly high modes, the vertical scales ranging from 50 to 180 m in the upper ocean. From an energy perspective, PSI mainly occurs in the critical latitudinal zone from 13–15ºN. In this zone, the incident internal tide loses ~14% energy in the mature state of PSI. PSI triggers a mixing elevation of O(10<sup>-5</sup>–10<sup>-4</sup> m<sup>2</sup>/s) in the upper ocean at the critical latitude, which is several times larger than the background value. The contribution of PSI to the internal tide energy loss and associated enhanced mixing may differ regionally and is closely dependent on the intensity and duration of background internal tide. The results elucidate the far-field dissipation mechanism by PSI in connecting interior mixing with remotely generated K<sub>1</sub> internal tides in the Luzon Strait.</p>

Observation and inversion of very-low-frequency seismo-acoustic fields in the South China Sea

2020 ◽  
Vol 148 (6) ◽  
pp. 3992-4001
Author(s):  
Shuyuan Du ◽  
Jingpu Cao ◽  
Shihong Zhou ◽  
Yubo Qi ◽  
Lei Jiang ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Low Frequency ◽  
The South China Sea ◽  
Acoustic Fields ◽  
The South ◽  
Very Low Frequency ◽  
China Sea ◽  
And Inversion
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