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

Cai, Zheng-Li; Gan, Jianping

doi:10.1175/jpo-d-17-0002.1

Cited by 7 publications

(7 citation statements)

References 48 publications

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“…In agreement with the idealized simulations in Cai and Gan (2017), the residual eddy train has a signature in the full SSH field toward a strengthening of the anticyclones that develop in summer. The change of size and magnitude, as well as the movement of the anticyclonic‐cyclonic‐anticyclonic pattern follows that of the riverine input which in turn is transported according to the monsoon winds.…”

Section: Freshwater Dependencesupporting

confidence: 87%

“…where overbars indicate time averages over the month of August, the primes deviations from these means, σ θ is the horizontally averaged potential density referenced to the surface, u and v are the zonal and meridional velocity components, and ρ is density. In agreement with the idealized simulations in Cai and Gan (2017), the residual eddy train has a signature in the full SSH field toward a strengthening of the anticyclones that develop in summer. The change of size and magnitude, as well as the movement of the anticyclonic-cyclonic-anticyclonic pattern follows that of the riverine input which in turn is transported according to the monsoon winds.…”

Section: Residual Eddy Trainsupporting

confidence: 85%

“…Over the summer, months long‐lived anticyclonic eddies (up to three) form along the jet meanders bringing the river plume water offshore (see Figures 5 and 6 for the SSH evolution from June to August at the two resolutions). Cai and Gan (2017) used an idealized circular basin model to show that the anticyclonic eddy train originates from the separated jet and its downstream meandering, and that the stratification modulates intensity and vertical extension of the anticyclones. They analyzed the vorticity balance and found that its formation is due to baroclinic instability of the jet, as to be expected, as it is favored by stratification.…”

Section: Modeled Circulationmentioning

confidence: 99%

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Dynamical Impact of the Mekong River Plume in the South China Sea

2022

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The South China Sea (SCS) is the largest marginal sea in Southeast Asia. It occupies the region from the equator to 23°N and from 99°E to 121°E with a maximum depth of over 5,000 m. It connects to the Sulu and Java Seas in the south through several shallow passages, and with the Pacific Ocean through the deep (∼2,000 m) Luzon Strait in the north. Exchange of shelf waters between the South China Sea and the East China Sea occurs through the Taiwan Strait at a sill depth of 60 m. Two broad shelves with depth shallower than 200 m are located on the northwestern and southwestern SCS, bordering the central, bowl-shaped deep basin (Hu et al., 2000). The SCS circulation is strongly influenced by the monsoonal winds (Daryabor et al., 2016). In winter, northeasterly winds prevail over the whole region with an average magnitude of 9 ms −1 and the coastal upwelling off the coast of Vietnam is suppressed due to the wind-driven cyclonic circulation cell (Chao et al., 1996). In contrast, the weaker southwest summer monsoon winds from June to September, with an average magnitude of 6 ms −1 , induce coastal upwelling that brings colder and saltier water to the surface (Wang et al., 2015). As a result of the wind upwelling, two distinct circulation cells are visible during this season (Dippner et al., 2011). The summer monsoon also brings intense rainfall over the ocean and Indochina, which drives large pulses of riverine flow into the SCS via the Mekong River (Shaw & Chao, 1994). The Mekong River originates in the Tibetan Plateau in China, drains a nearly 800,000 km 2 watershed and discharges into the SCS at the Mekong Delta in Vietnam with an annual mean

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Section: Freshwater Dependencesupporting

confidence: 87%

Section: Residual Eddy Trainsupporting

confidence: 85%

Section: Modeled Circulationmentioning

confidence: 99%

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Dynamical Impact of the Mekong River Plume in the South China Sea

2022

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“…To isolate the physics and identify the associated forcing mechanism of the layered circulation, we adopt an idealized geometry that preserves the spatial scale and characteristic of the SCS, similar to that of Cai and Gan (). In this process‐oriented modeling study, the SCS basin model domain is represented by a circularly shaped basin (Figure a).…”

Section: The Numerical Ocean Modelmentioning

confidence: 99%

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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“…A large enough horizontal density gradient would provide enough energy and mass for the generation of mesoscale eddies in the SCS [33]. In the Luzon Strait, the Kuroshio may form a "current jacket", which could shear mesoscale eddies [58,59].…”

Section: The Generation and Extinction Of Simple And Complex Eddy Processesmentioning

confidence: 99%

A Census of the 1993–2016 Complex Mesoscale Eddy Processes in the South China Sea

Wang

Liang

et al. 2019

Water

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Mesoscale eddy process with at least one splitting and/or merging event can be defined as either a complex process or a simple process. Investigation of the difference between these two categories could provide new insights into how different factors, such as the seabed topography, Kuroshio intrusion, and winds, affect the origin, migration, and decay of the mesoscale eddies. This study compared the characteristics of the complex against the simple eddy processes in the South China Sea (SCS) from 1993 to 2016. We comprehensively analyzed the eddy processes with regards to their characteristic points, trajectories, and networks. The simple and complex processes share many similarities but do show significantly different behaviors. Both the simple and complex processes mainly start from the eastern SCS. However, the complex processes mainly vanish in the western SCS whereas the simple processes disappear almost everywhere across the SCS. The complex processes last longer and migrate more than the simple processes. Lastly, the complex processes mainly move westward within the community. The complex processes can be further categorized into complex anticyclonic and cyclonic eddy processes. Spatially, the splitting and merging events mainly occur in the southwest of Taiwan, northwest of the Luzon Island, and the southeast of Vietnam. Temporally, the merging and splitting events mainly occur in the fall. The interaction among the communities reveals the different migration patterns of the complex anticyclonic and cyclonic eddy processes in the SCS.

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

Cited by 7 publications

References 48 publications

Dynamical Impact of the Mekong River Plume in the South China Sea

Dynamical Impact of the Mekong River Plume in the South China Sea

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

A Census of the 1993–2016 Complex Mesoscale Eddy Processes in the South China Sea

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