The Effects of Thermohaline Circulation on Wind-Driven Circulation in the South China Sea

Wang, Guihua; Huang, Rui Xin; Su, Jilan; Chen, Dake

doi:10.1175/jpo-d-11-0227.1

Cited by 21 publications

(10 citation statements)

References 27 publications

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“…The WS along the zero WSC line was 0.1 Pa, and its magnitude decreased southward and northward from that line. The wind pattern is similar to those used in previous studies (Gan et al 2006(Gan et al , 2016aWang et al 2012) and the sensitivity tests showed that the eddy-train formation was not sensitive to the position of the zero WSC line. The standard case reproduced well the characteristics of the observed the eddy train, as demonstrated in section 4.…”

Section: Numerical Ocean Model Description and Implementationsupporting

confidence: 77%

“…The SCS has mesoscale eddies that influence the dynamics in the basin and play an important role in heat and salt transport (Chen et al 2012). These eddies have been extensively studied using hydrographic data (e.g., Wang et al 2008;Cheng and Qi 2010;Hu et al 2011Hu et al , 2012Zhang et al 2013Zhang et al , 2016 and numerical models (e.g., Wu and Chiang 2007;Wang and Gan 2014;Lin et al 2015;Sun et al 2016).…”

Section: Introductionmentioning

confidence: 99%

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Formation and Dynamics of a Long-Lived Eddy Train in the South China Sea: A Modeling Study

Cai

Gan

2017

Journal of Physical Oceanography

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A process-oriented numerical modeling study was conducted to investigate the formation and underlying forcing of an anticyclonic eddy train observed in the northern South China Sea. Observations showed that long-lived anticyclonic eddies formed an eddy train along an eastward separated jet across the northern South China Sea in summer. The eddy train plays a critical role in regulating ocean circulation in the region. Forced by the southwesterly monsoon and prevailing dipole wind stress curl in the summer, the northward coastal jet separates from the west boundary of the South China Sea basin and overshoots northeastward into the basin. The anticyclonic recirculation of the separated jet forms the first anticyclonic eddy in the eddy train. The jet meanders downstream with a strong negative shear vorticity that forms a second and a third anticyclonic eddy along the jet’s path. These three eddies form the eddy train. These eddies weaken gradually with depth from surface, but they can extend to approximately 500 m deep. The inherent stratification in the region regulates the three-dimensional scale of the anticyclonic eddies and constrains their intensity vertical extension by weakening the geostrophic balance within these eddies. Analyses of the vorticity balance indicate that the eddy train’s negative vorticity originates from the beta effect of northward western boundary current and from the subsequent downstream vorticity advection in the jet. The jet separation is a necessary condition for the formation of the eddy train, and the enhanced stratification, increased summer wind stress, and associated negative wind stress curl are favorable conditions for the formation of the anticyclonic eddies.

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Section: Numerical Ocean Model Description and Implementationsupporting

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Formation and Dynamics of a Long-Lived Eddy Train in the South China Sea: A Modeling Study

Cai

Gan

2017

Journal of Physical Oceanography

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“…Due to the rough topography in the SCS and the Luzon Strait, tidal dissipation in the deep ocean can be substantially enhanced, and a large amount of barotropic tidal energy is converted into internal tides, internal waves break, and diapycnal mixing ensure [ Wang et al ., ]. The enhanced diapycnal diffusivity in the SCS and the Luzon Strait is elevated by 2 orders of magnitude over that of the smooth bathymetry in the North Pacific, reaching O(10 −3 m 2 s −1 ) [ Tian et al ., ].…”

Section: Conclusion and Discussionmentioning

confidence: 99%

On the dynamics of the South China Sea deep circulation

2013

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[1] In the South China Sea (SCS), the deep water is confined to a bowel-type trench, and the maximum depth is approximately 4700 m. The Luzon Strait is the only deep connection between the SCS and the Pacific Ocean, with the deepest sill at about 2400 m in the Bashi Channel. Using the Hybrid Coordinate Ocean Model, this study gives a good description of the SCS deep circulation. The most obvious features are basin-scale cyclonic gyre and western intensification. The gyre is elliptical shaped, and its major axis is northeastsouthwest. A numerical experiment is designed to investigate what could be possibly responsible for the SCS deep circulation. The results reveal that the deepwater overflow through the Luzon Strait controls over the basin-scale circulation structure in the deep SCS basin. The driving mechanism is elucidated based on the potential vorticity (PV) integral constraint, which means the PV inflow across the boundary is balanced by the net PV dissipation along the boundary.

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“…This suggests that the vertical transports from the upper and lower layers produce negative VOR_DIV in the middle layer. G. Wang et al () similarly revealed that the anticyclonic circulation component (negative vorticity) was induced in a layer by upwelling from the base of the layer. Therefore, the vorticity input induced by the vertical transport of water is the major response to the external vorticity flux in the middle and lower layers and can act as an intrinsic link between the circulations in different layers.…”

Section: Discussionmentioning

confidence: 97%

Coupled External‐Internal Dynamics of Layered Circulation in the South China Sea: A Modeling Study

Cai

Gan

2019

JGR Oceans

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The external inflow/outflow through straits on the periphery of the South China Sea (SCS) and the associated internal response of vertical transport over the broad continental slope form and sustain a cyclonic‐anticyclonic‐cyclonic (CAC) circulation in the upper‐middle‐lower layer in the SCS. We conduct a process‐oriented numerical study to investigate the underlying coupled external‐internal dynamics that remains unknown, despite that the dynamics plays a critical role in forming and sustaining the CAC circulation. External sandwich‐like inflow‐outflow‐inflow in the water column through the Luzon Strait forms a three‐dimensional CAC slope current over the curving slope topography in the SCS basin, in which the downward/upward transport associated with the cross‐slope motion is established. The along‐slope current over the basin provides vorticity through the beta effect and accounts for the most external planetary vorticity input through the strait in the upper layer of the SCS, while the vorticity induced by the vertical transport is the major response to the external vorticity flux in the middle and lower layers. We illustrate the critical role of the vertical transport in linking the vorticity among the different layers for the development and sustenance of the CAC circulation. The vertical transport is associated with the cross‐slope motion due to slope current‐topography interaction, which involves mainly in bottom frictional transport and geostrophic cross‐isobath transport by the pressure gradient force in the along‐slope direction. Pressure gradient force is generated by nonlinear vorticity advection and the beta effect of the background slope current.

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The Effects of Thermohaline Circulation on Wind-Driven Circulation in the South China Sea

Cited by 21 publications

References 27 publications

Formation and Dynamics of a Long-Lived Eddy Train in the South China Sea: A Modeling Study

Formation and Dynamics of a Long-Lived Eddy Train in the South China Sea: A Modeling Study

On the dynamics of the South China Sea deep circulation

Coupled External‐Internal Dynamics of Layered Circulation in the South China Sea: A Modeling Study

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