Mesoscale eddies in the South China Sea: Mean properties, spatiotemporal variability, and impact on thermohaline structure

Chen, Gengxin; Hou, Yijun; Chu, Xiaoqing

doi:10.1029/2010jc006716

Cited by 273 publications

(332 citation statements)

References 39 publications

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“…These long-lived trajectories represent between 35% and 50% of the number of tracks formed near the coast, the rest are short-lived eddies. Note that it does not exist an official definition for ''long-lived eddies'' and, depending on the authors, the choice of their minimal duration can vary from a few weeks to several months [e.g., Fang and Morrow, 2003;Chaigneau and Pizarro, 2005;Chaigneau et al, 2008;Sangr a et al, 2009;Kurczyn et al, 2012;Chelton et al, 2007Chelton et al, , 2011Chaigneau et al, 2009;Chen et al, 2011]. Here we refer to ''long-lived eddies'' as eddies having a lifetime longer than 30 days, that is consistent with previous studies Figure 2.…”

Section: 1002/2015jc010950supporting

confidence: 78%

Main eddy vertical structures observed in the four major Eastern Boundary Upwelling Systems

2015

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In the four major Eastern Boundary Upwelling Systems (EBUS), mesoscale eddies are known to modulate the biological productivity and transport near‐coastal seawater properties toward the offshore ocean, however little is known about their main characteristics and vertical structure. This study combines 10 years of satellite‐altimetry data and Argo float profiles of temperature and salinity, and our main goals are (i) to describe the main surface characteristics of long‐lived eddies formed in each EBUS and their evolution, and (ii) to depict the main vertical structure of the eddy‐types that coexist in these regions. A clustering analysis of the Argo profiles surfacing within the long‐lived eddies of each EBUS allows us to determine the proportion of surface and subsurface‐intensified eddies in each region, and to describe their vertical structure in terms of temperature, salinity and dynamic height anomalies. In the Peru‐Chile Upwelling System, 55% of the sampled anticyclonic eddies (AEs) have subsurface‐intensified maximum temperature and salinity anomalies below the seasonal pycnocline, whereas 88% of the cyclonic eddies (CEs) are surface‐intensified. In the California Upwelling System, only 30% of the AEs are subsurface‐intensified and all of the CEs show maximum anomalies above the pycnocline. In the Canary Upwelling System, ∼40% of the AEs and ∼60% of the CEs are subsurface‐intensified with maximum anomalies extending down to 800 m depth. Finally, the Benguela Upwelling System tends to generate ∼40–50% of weak surface‐intensified eddies and ∼50–60% of much stronger subsurface‐intensified eddies with a clear geographical distribution. The mechanisms involved in the observed eddy vertical shapes are discussed.

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Section: 1002/2015jc010950supporting

confidence: 78%

Main eddy vertical structures observed in the four major Eastern Boundary Upwelling Systems

2015

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“…Chen et al [75] pointed out that the cyclonic and AEs have different seasonal characteristics: more cyclonic eddies are formed in winter, while more anti-cyclonic eddies are formed in summer. The cyclonic eddies with minimum (maximum) radius and lifetimes appear in summer (winter), and the lifetime of the AEs is longer than that of the cyclonic eddies.…”

Section: Interaction Between Scswbc and Eddiesmentioning

confidence: 99%

“…The Eddy Kinetic Energy (EKE) ( Figure 5) is much larger in Z1 and Z4 regions than in Z2 and Z3 regions, and the maximum EKEs in Z1 and Z4 appear in winter and summer, respectively. Over the continental shelf of the northern SCS, the eddies propagate southwestward, and the speed is the largest of the whole SCS [75], probably due to the SCSWBC. This is different from the common characteristic that the propagating speed is larger in the lower latitude.…”

Section: Interaction Between Scswbc and Eddiesmentioning

confidence: 99%

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%

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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Mesoscale eddies in the South China Sea: Mean properties, spatiotemporal variability, and impact on thermohaline structure

Cited by 273 publications

References 39 publications

Main eddy vertical structures observed in the four major Eastern Boundary Upwelling Systems

Main eddy vertical structures observed in the four major Eastern Boundary Upwelling Systems

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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