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

2017 ◽  
Vol 47 (11) ◽  
pp. 2793-2810 ◽  
Author(s):  
Zhongya Cai ◽  
Jianping Gan
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Northern South China Sea ◽  
Anticyclonic Eddy ◽  
The South China Sea ◽  
The South ◽  
Wind Stress Curl ◽  
China Sea ◽  
Anticyclonic Eddies

AbstractA 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.

scholarly journals An exceptional anticyclonic eddy in the South China Sea in 2010

2014 ◽  
Vol 119 (2) ◽  
pp. 881-897 ◽  
Author(s):  
Xiaoqing Chu ◽  
Huijie Xue ◽  
Yiquan Qi ◽  
Gengxin Chen ◽  
Qingwen Mao ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Anticyclonic Eddy ◽  
The South China Sea ◽  
The South ◽  
China Sea

Michaelcallianassa sinica sp. nov. (Crusacea, Decapoda, Thalassinidea, Callianassidae) from the South China Sea

Zootaxa ◽  
2009 ◽  
Vol 2294 (1) ◽  
pp. 39-46
Author(s):  
WENLIANG LIU ◽  
RUIYU LIU
Keyword(s):  
New Species ◽  
South China Sea ◽  
South China ◽  
Type Species ◽  
Northern South China Sea ◽  
The South China Sea ◽  
Beibu Gulf ◽  
The South ◽  
China Sea ◽  
A New Species

A new species, Michaelcallianassa sinica, from the Beibu Gulf (Tonkin Gulf), northern South China Sea, is described and illustrated. The new species is readily distinguished from M. indica Sakai, 2002, the type species of the genus, by its short uropodal endopod and exopod, and elongated carpus of the minor cheliped.

scholarly journals The Changing Influences of ENSO and the Pacific Meridional Mode on Mesoscale Eddies in the South China Sea

2019 ◽  
Vol 32 (3) ◽  
pp. 685-700 ◽  
Author(s):  
Pengfei Tuo ◽  
Jin-Yi Yu ◽  
Jianyu Hu
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Southern Oscillation ◽  
The South China Sea ◽  
Eddy Correlation ◽  
The South ◽  
Vector Method ◽  
China Sea ◽  
The Pacific

This study finds that the correlation between El Niño–Southern Oscillation (ENSO) and the activity of mesoscale oceanic eddies in the South China Sea (SCS) changed around 2004. The mesoscale eddy number determined from satellite altimetry observations using a geometry of the velocity vector method was significantly and negatively correlated with the Niño-3.4 index before 2004, but the correlation weakened and became insignificant afterward. Further analyses reveal that the ENSO–eddy relation is controlled by two major wind stress forcing mechanisms: one directly related to ENSO and the other indirectly related to ENSO through its subtropical precursor—the Pacific meridional modes (PMMs). Both mechanisms induce wind stress curl variations over the SCS that link ENSO to SCS eddy activities. While the direct ENSO mechanism always induces a negative ENSO–eddy correlation through the Walker circulation, the indirect mechanism is dominated by the northern PMM (nPMM), resulting in a negative ENSO–eddy correlation before 2004, and by the southern PMM (sPMM) after 2004, resulting in a positive ENSO–eddy correlation. As a result, the direct and indirect mechanisms enhance each other to produce a significant ENSO–eddy relation before 2004, but they cancel each other out, resulting in a weak ENSO–eddy relation afterward. The relative strengths of the northern and southern PMMs are the key to determining the ENSO–eddy relation and may be related to a phase change of the interdecadal Pacific oscillation.

Impacts of a wind stress and a buoyancy flux on the seasonal variation of mixing layer depth in the South China Sea

2013 ◽  
Vol 32 (9) ◽  
pp. 30-37 ◽  
Author(s):  
Xianjun Xiao ◽  
Dongxiao Wang ◽  
Wen Zhou ◽  
Zuqiang Zhang ◽  
Yinghao Qin ◽  
...  
Keyword(s):  
Seasonal Variation ◽  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
Mixing Layer ◽  
The South China Sea ◽  
Buoyancy Flux ◽  
The South ◽  
Layer Depth ◽  
China Sea

A comparison of wind stress datasets for the South China Sea

2015 ◽  
Vol 65 (5) ◽  
pp. 721-734 ◽  
Author(s):  
Zhan Lian ◽  
Guohong Fang ◽  
Zexun Wei ◽  
Gang Wang ◽  
Baonan Sun ◽  
...  
Keyword(s):  
South China Sea ◽  
Wind Stress ◽  
South China ◽  
The South China Sea ◽  
The South ◽  
China Sea

scholarly journals A clustering analysis of eddies' spatial distribution in the South China Sea

Ocean Science ◽  
2013 ◽  
Vol 9 (1) ◽  
pp. 171-182 ◽  
Author(s):  
J. Yi ◽  
Y. Du ◽  
X. Wang ◽  
Z. He ◽  
C. Zhou
Keyword(s):  
South China Sea ◽  
South China ◽  
Seasonal Variations ◽  
Clustering Analysis ◽  
The South China Sea ◽  
The South ◽  
Mixed Effect ◽  
China Sea ◽  
Generation Mechanisms ◽  
Anticyclonic Eddies

Abstract. Spatial variation is important for studying the mesoscale eddies in the South China Sea (SCS). To investigate such spatial variations, this study made a clustering analysis on eddies' distribution using the K-means approach. Results showed that clustering tendency of anticyclonic eddies (AEs) and cyclonic eddies (CEs) were weak but not random, and the number of clusters were proved greater than four. Finer clustering results showed 10 regions where AEs densely populated and 6 regions for CEs in the SCS. Previous studies confirmed these partitions and possible generation mechanisms were related. Comparisons between AEs and CEs revealed that patterns of AE are relatively more aggregated than those of CE, and specific distinctions were summarized: (1) to the southwest of Luzon Island, AEs and CEs are generated spatially apart; AEs are likely located north of 14° N and closer to shore, while CEs are to the south and further offshore. (2) The central SCS and Nansha Trough are mostly dominated by AEs. (3) Along 112° E, clusters of AEs and CEs are located sequentially apart, and the pairs off Vietnam represent the dipole structures. (4) To the southwest of the Dongsha Islands, AEs are concentrated to the east of CEs. Overlaps of AEs and CEs in the northeastern and southern SCS were further examined considering seasonal variations. The northeastern overlap represented near-concentric distributions while the southern one was a mixed effect of seasonal variations, complex circulations and topography influences.

A multi-year investigation of the Temoridae (Copepoda, Calanoida) assemblage succession within the interplay waters of the northern South China Sea

Crustaceana ◽  
2020 ◽  
Vol 93 (3-5) ◽  
pp. 519-540
Author(s):  
Li-Chun Tseng ◽  
Yan-Guo Wang ◽  
Guang-Shan Lian ◽  
Jiang-Shiou Hwang
Keyword(s):  
South China Sea ◽  
South China ◽  
Northern South China Sea ◽  
Seasonal Succession ◽  
Mesh Size ◽  
Abundant Species ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
The Kuroshio

Abstract The South China Sea is the largest marginal sea in the world. The northern South China Sea has a complex hydrographic system affected by interplay waters of the Kuroshio Branch Current and the South China Sea waters. To understand the changes in the community structure of the planktonic calanoid copepod family Temoridae in relation to the interplay waters, we collected zooplankton samples in the northern South China Sea from surface waters (0 to 2 m) from November 2001 to January 2007 during 24 research cruises using a standard North Pacific zooplankton net (with a mesh size of 200 μm, a length of 1.8 m, and a mouth diameter of 0.45 m). Among a total of 253 samples, 5 species belonging to 3 genera of Temoridae were identified: Eurytemora pacifica Sato, 1913, Temora discaudata Giesbrecht, 1889, Temora stylifera (Dana, 1849), Temora turbinata (Dana, 1849), and Temoropia mayumbaensis Scott T., 1894. The 3 most abundant species were: T. turbinata (relative abundance, RA: 53.28%; mean density ± standard deviation, MD: 29.33 ± 89.53 ind. m−3), T. stylifera (RA: 36.02%, MD: 19.83 ± 145.22 ind. m−3), and T. discaudata (RA: 7.70%, MD: 4.24 ± 11.82 ind. m−3). The 3 most frequently occurring species were: T. turbinata (occurrence ratio, OR: 52.17%), T. discaudata (OR: 35.18%), and T. stylifera (OR: 9.88%). A noteworthy discovery in our samples was E. pacifica, a marine and brackish water species, collected from 3 stations located near the Kuroshio Branch Current in April 2003. This is the only month when this species was recorded during the investigation period. Variations of dominant species of Temoridae show a clear pattern of seasonal succession. The total abundance was significantly higher in the third quarter (September-November, 116.98 ± 314.49 ind. m−3) than in the fourth quarter (December-February, 24.26 ± 47.72 ind. m−3) (, one-way ANOVA). In general, the present results demonstrate that the assemblages of the Temoridae are very much structured by the water masses of the Kuroshio Current and the South China Sea.

Observing an anticyclonic eddy in the South China Sea using multiple underwater gliders

2018 ◽  
Author(s):  
Shufeng Li ◽  
Shuxin Wang ◽  
Fumin Zhang ◽  
Yuhong Wang ◽  
Yuhong Liu ◽  
...  
Keyword(s):  
South China Sea ◽  
South China ◽  
Anticyclonic Eddy ◽  
The South China Sea ◽  
The South ◽  
China Sea ◽  
Underwater Gliders
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