Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004

Wang, Dongxiao; Xu, Hongzhou; Lin, Jing; Hu, Jianyu

doi:10.1007/s10872-008-0076-3

Cited by 131 publications

(91 citation statements)

References 25 publications

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“…Roles of mixing associated with vortex Rossby waves and near-internal waves in determining the mescoscale circulation are detected by Cardona and Bracco [2012]. In addition, previous results have substantiated the presence of seasonal [e.g., He et al, 2002;Wang et al, 2003bWang et al, , 2008Chen et al, 2009;Zhuang et al, 2010b;1 Wang et al, 2012] and interannual [e.g., Hwang and Chen, 2000;Cheng and Qi, 2010] variations of the mescoscale process in the SCS. However, sources and sinks of the eddy energy in the SCS remain to be mapped and quantified.…”

Section: Introductionmentioning

confidence: 72%

Eddy energy sources and sinks in the South China Sea

Yang

Liu

et al. 2013

JGR Oceans

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[1] The eddy energy sources and sinks in the South China Sea (SCS) are studied based on a high-resolution ocean circulation model. Eddies are found to acquire their energy from barotropic instability (BT), the release of available potential energy (APE) associated with baroclinic instability (BC) and horizontal convergence from surrounding areas, while they lose energy due to turbulent processes. Both the eddy energy sources and sinks show western intensification with their maximum around the southwestern SCS where most of the wind-input energy occurs, and the Luzon Strait where the Kuroshio intrudes the SCS in winter. Unlike that in the open ocean, the eddy energy in the inner SCS is confined to the upper layer. Besides, the eddy energy indicates clear seasonal variability, especially at the Luzon Strait where the eddy activity is much stronger in winter than in summer. Energy budget analysis suggests that APE releasing is found to be the most important eddy energy source, accounting for over 60% of the total, followed by energy convergence from surrounding areas in horizontal direction (around 20%) and energy released from BT (around 15%). Most of the generated energy is mainly balanced by the turbulent processes, while both of the downward energy flux and tendency term are negligible.

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Section: Introductionmentioning

confidence: 72%

Eddy energy sources and sinks in the South China Sea

Yang

Liu

et al. 2013

JGR Oceans

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“…Wang et al [57] (Figure 3). Both eddies moved southwestward along the continental shelf in the northern SCS after their generations, and their moving speeds are similar to that of the first baroclinic Rossby wave.…”

Section: Interannual Variability Of the Scswbcmentioning

confidence: 98%

Progress of regional oceanography study associated with western boundary current in the South China Sea

et al. 2013

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Recent progress of physical oceanography in the South China Sea (SCS) associated with the western boundary current (WBC) and eddies is reviewed in this paper. It includes Argo observations of the WBC, eddy detection in the WBC based on satellite images, cross-continental shelf exchange in the WBC, eddy-current interaction, interannual variability of the WBC, air-sea interaction, the SCS throughflow (SCSTF), among others. The WBC in the SCS is strong, and its structure, variability and dynamic processes on seasonal and interannual time scales are yet to be fully understood. In this paper, we summarize progresses on the variability of the WBC, eddy-current interaction, air-sea interaction, and the SCSTF achieved in the past few years. Firstly, using the drifting buoy observations, we point out that the WBC becomes stronger and narrower after it reaches the central Vietnam coast. The possible mechanisms influencing the ocean circulation in the northern SCS are discussed, and the dynamic mechanisms that induce the countercurrent in the region of northern branch of WBC in winter are also studied quantitatively using momentum balance. The geostropic component of the WBC was diagnosed using the ship observation along 18°N, and we found that the WBC changed significantly on interannual time scale. Secondly, using the ship observations, two anti-cyclonic eddies in the winter of 2003/2004 in the northern SCS, and three anti-cyclonic eddies in the summer of 2007 along 18°N were studied. The results show that the two anti-cyclonic eddies can propagate southwestward along the continental shelf at the speed of first Rossby wave (~0.1 m s 1 ) in winter, and the interaction between the three anti-cyclonic eddies in summer and the WBC in the SCS is preliminarily revealed. Eddies on the continental shelf of northern SCS propagated southeastward with a maximum speed of 0.09 m s 1 , and those to the east of Vietnam coast had the largest kinetic energy, both of which imply strong interaction between eddy activity and WBC in the SCS. Thirdly, strong intraseasonal variability (ISV) of sea surface temperature (SST) near the WBC regions was found, and the ISV signal of SST in winter weakens the ISV signal of latent heat flux by 20%. Fourthly, the long-term change of SCSTF volume transport and its connection with the ocean circulation in the Pacific were discussed.South China Sea, western boundary current, eddy, eddy-current interaction, intraseasonal variability, South China Sea thoughflow Citation:Wang D X, Liu Q Y, Xie Q, et al. Progress of regional oceanography study associated with western boundary current in

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“…The anticyclonic eddies (AEs) in the NSCS found in the previous studies usually have a horizontal diameter of about 150-250 km and a vertical scale over 500 m and move southwestward at a speed (∼10 cm/s) of baroclinic Rossby wave along the continental slope of the NSCS (Wang and Chern 1987a, b;Li et al 1998;Guo et al 2007;Wang et al 2008a;Chen et al 2011b). The generation of an AE during winter is mainly attributed to the shedding from the Kuroshio loop current when its transport is weakened, and their formation is usually associated with the cyclonic eddy development next to it (Jia et al 2005;Nan et al 2011c).…”

Section: Introductionmentioning

confidence: 99%

“…Mesoscale eddies in the northern South China Sea (NSCS) have been documented and extensively studied (Li et al 1998;Metzger and Hurlburt 2001;Wang et al , 2008aJia and Liu 2004;Jia et al 2005;Wu and Chiang 2007;Yuan et al 2007;Chen et al 2010;Nan et al 2011a, c). Most of them are found to have originated from the vicinity of Luzon Strait (LS), and then propagate westward, resulting in large mesoscale sea-level variability along the continental slope (Zhuang et al 2010a).…”

Section: Introductionmentioning

confidence: 99%

“…Mechanisms of eddy formation in the NSCS could be summarized into three types according to the previous studies. The first type is eddy shedding from the Kuroshio loop current (Li et al 1998;Metzger and Hurlburt 2001;Jia and Liu 2004;Jia et al 2005;Yuan et al 2006;Wu and Chiang 2007;Wang et al 2008a;Chen et al 2011a;Nan et al 2011c), which is caused by the frontal instability of the Kuroshio branch that intrudes into the northeastern SCS (NESCS). The second type is eddy generated locally by wind stress curl Wang et al 2008b); the orographic wind jet and enhanced wind stress curl in the lee of the Taiwan Island and Luzon Island chains could lead to stronger Ekman pumping and spin up eddies.…”

Section: Introductionmentioning

confidence: 99%

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Evolution of an anticyclonic eddy southwest of Taiwan

Wang

et al. 2013

Ocean Dynamics

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Satellite images of sea-surface temperature, surface chlorophyll a concentration, and sea-level anomaly, together with ocean reanalysis data of Asia and Indian-Pacific Ocean (AIPOcean1.0), are utilized to study the three-dimensional characteristics and evolution of an anticyclonic warm eddy adjacent to the southwest coast of Taiwan during October and November 2006. Originated from the Kuroshio intrusion in the Luzon Strait, but unlike previously found westward moving anticyclonic eddies (AE) in the northeastern South China Sea, this AE was so close to the Taiwan coast and stayed where it was formed for over 1 month until it dissipated. Energy analysis is utilized to study the evolution process of the AE, and it shows that the barotropic instability (BTI) and baroclinic instability introduced by the Kuroshio intrusion flow appear to be the main energy sources for the AE. Periodical enhancement/relaxation of local northeasterly monsoon and its associated negative wind stress curl modify the current patterns in this region, reinforce the intraseasonal variability of the Kuroshio intrusion flow, and act together with Kuroshio to form the AE. Eddies detected from AIPOcean1.0 data also show that AEs are most likely to be generated southwest of Taiwan during the transition period of summer monsoon to winter monsoon, and generally, the BTI of Kuroshio intrusion contributes more than the direct wind stress work to the increase of the eddy kinetic energy for the generation and growth of the AEs.

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Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004

Cited by 131 publications

References 25 publications

Eddy energy sources and sinks in the South China Sea

Eddy energy sources and sinks in the South China Sea

Progress of regional oceanography study associated with western boundary current in the South China Sea

Evolution of an anticyclonic eddy southwest of Taiwan

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