An observed cyclonic eddy associated with boundary current in the northwestern South China Sea

Authors

  • Junmin Li State Key Laboratory of Tropical Oceanography (LTO), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
  • Zhiyou Jing State Key Laboratory of Tropical Oceanography (LTO), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
  • Senhui Jiang State Key Laboratory of Tropical Oceanography (LTO), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
  • Dongxiao Wang State Key Laboratory of Tropical Oceanography (LTO), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China
  • Tong Yan State Key Laboratory of Tropical Oceanography (LTO), South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou 510301, China

Keywords:

offshore jet, mooring observation

Abstract

A cyclonic eddy detected in the northwestern South China Sea during the summer of 2011 is investigated using both satellite data and several sets of in situ observations including cruise measurements and a mooring line. The eddy was generated to the west of the Zhongsha Islands in early June and then propagated northwestward. In July and August, when the cyclonic gyre originating from the offshore jet recirculation east of Vietnam matured, the eddy was absorbed into the gyre and strengthened by it. The eddy regulated the thermohaline characteristics and the currents of the entire water column. Along-slope boundary currents (toward the northeast in summer) were completely reversed from the surface to about 1300 m below. The thermohaline in deep water (660–950 m) showed a significant response to the presence of the eddy, with the isotherms and isohalines rising up to 100 m. The recurrence of the phenomenon is further explored by a statistical analysis of satellite observations. Results suggest the presence of a cyclonic eddy and abnormal offshore jets are closely associated with the El Nino Southern Oscillation events.

References

Chaigneau, A., Eldin, G., Dewitte, B., 2009. Eddy activity in the four major upwelling systems from satellite altimetry (1992–2007). Prog. Oceanogr. 83, 117–123.

Chaigneau, A., Le Texier, M., Eldin, G., Grados, C., Pizarro, O., 2011. Vertical structure of mesoscale eddies in the eastern South Pacific Ocean: A composite analysis from altimetry and Argo profiling floats. J. Geophys. Res. 116, C11025.

Chen, G., Gan, J., Xie, Q., Chu, X., Wang, D., Hou, Y., 2012. Eddy heat and salt transports in the South China Sea and their seasonal modulations. J. Geophys. Res. 117, C05021.

Chen, G., Hou, Y., Zhang, Q., Chu, X., 2010. The eddy pair off eastern Vietnam: Interannual variability and impact on thermohaline structure. Cont. Shelf Res. 30, 715–723.

Chen, G., Hou, Y., Chu, X., 2011. Mesoscale eddies in the South China Sea: Mean properties, spatiotemporal variability, and impact on thermohaline structure. J. Geophys. Res. 116, C06018.

Chern, C.-S., Wang, J., 2003. Numerical Study of the Upper-Layer Circulation in the South China Sea. J. Oceanogr. 59, 11–24.

Chu, X., Xue, H., Qi, Y., Chen, G., Mao, Q., Wang, D., Chai, F., 2013. An exceptional warm eddy in the South China Sea in 2010. J. Geophys. Res. 119, 881–897.

Fang, G., Wang, G., Fang, Y., Fang, W., 2012. A review on the South China Sea western boundary current. Acta Oceanol. Sin. 31, 1–10.

He, Z., Wang, D., Hu, J., 2002. Features of eddy kinetic energy and variations of upper circulation in the South China Sea. Acta Oceanol. Sin. 21, 305–314.

Hu, J., Gan, J., Sun, Z., Zhu, J., Dai, M., 2011. Observed three-dimensional structure of a cold eddy in the southwestern South China Sea. J. Geophys. Res. 116, C05016.

Hu, J., Kawamura, H., Hong, H., Qi, Y., 2000. A Review on the Currents in the South China Sea: Seasonal Circulation, South China Sea Warm Current and Kuroshio Intrusion. J. Oceanogr. 56, 607–624.

Hwang, C., Chen, S.-A., 2000. Circulations and eddies over the South China Sea derived from TOPEX/Poseidon altimetry. J. Geophys. Res. 105, 23943–23965.

Liu, K.K., Chao, S.Y., Shaw, P.T., Gong, G.C., Chen, C.C., Tang, T.Y., 2002. Monsoon-forced chlorophyll distribution and primary production in the South China Sea: observations and a numerical study. Deep Sea Res., Part I 49, 1387–1412.

Liu, Z., Yang, H., Liu, Q., 2001. Regional Dynamics of Seasonal Variability in the South China Sea. J. Phys. Oceanogr. 31, 272–284.

Morimoto, A., Yoshimoto, K., Yanagi, T., 2000. Characteristics of Sea Surface Circulation and Eddy Field in the South China Sea Revealed by Satellite Altimetric Data. J. Oceanogr. 56, 331–344.

Nan, F., He, Z., Zhou, H., Wang, D., 2011. Three long-lived anticyclonic eddies in the northern South China Sea. J. Geophys. Res. 116, C05002.

Qu, T., 2000. Upper-Layer Circulation in the South China Sea. J. Phys. Oceanogr. 30, 1450–1460.

Su, J., 2004. Overview of the South China Sea circulation and its influence on the coastal physical oceanography outside the Pearl River Estuary. Cont. Shelf Res. 24, 1745–1760.

Sutyrin, G.G., Grimshaw, R., 2010. The long-time interaction of an eddy with shelf topography. Ocean Model. 32, 25–35.

Wang, B., Huang, F., Wu, Z., Yang, J., Fu, X., Kikuchi, K., 2009. Multi-scale climate variability of the South China Sea monsoon: A review. Dynam. Atmos. Oceans. 47, 15–37.

Wang, D., Liu, Q., Xie, Q., He, Z., Zhuang, W., Shu, Y., Xiao, X., Hong, B., Wu, X., Sui, D., 2013. Progress of regional oceanography study associated with western boundary current in the South China Sea. Chin. Sci. Bull., 1–11.

Wang, D., Xu, H., Lin, J., Hu, J., 2008. Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004. J. Oceanogr. 64, 925–935.

Wang, G., Su, J., Chu, P.C., 2003. Mesoscale eddies in the South China Sea observed with altimeter data. Geophys. Res. Lett. 30, 2121.

Wang, L., Koblinsky, C.J., Howden, S., 2000. Mesoscale variability in the South China Sea from the TOPEX/Poseidon altimetry data. Deep Sea Res., Part I 47, 681–708.

Wu, C.-R., Shaw, P.-T., Chao, S.-Y., 1998. Seasonal and interannual variations in the velocity field of the South China Sea. J. Oceanogr. 54, 361–372.

Wu, C.-R., Shaw, P.-T., Chao, S.-Y., 1999. Assimilating altimetric data into a South China Sea model. J. Geophys. Res. 104, 29987–30005.

Wyrtki, K., 1961. Physical oceanography of the Southeast Asian waters: Scientific results of marine investigations of the South China Sea and the Gulf of Thailand, NAGA Rep. 2, 195 pp., Scripps Inst. of Oceanogr., La Jolla, Calif.

Xiu, P., Chai, F., Shi, L., Xue, H., Chao, Y., 2010. A census of eddy activities in the South China Sea during 1993–2007. J. Geophys. Res. 115, C03012.

Yu, Z., Shen, S., McCreary, J.P., Yaremchuk, M., Furue, R., 2007. South China Sea throughflow as evidenced by satellite images and numerical experiments. Geophys. Res. Lett. 34, L01601.

Zhuang, W., Xie, S.-P., Wang, D., Taguchi, B., Aiki, H., Sasaki, H., 2010. Intraseasonal variability in sea surface height over the South China Sea. J. Geophys. Res. 115, C04010.

Downloads

Published

2015-10-02

Issue

Vol. 18 No. 4 (2015): Tropical Marine Environmental Change

Section

Research article

License

Manuscripts must be original. They must not be published or be under consideration for publication elsewhere, in whole or in part. It is required that the lead author of accepted papers complete and sign the MSU Press AEHM Author Publishing Agreement and provide it to the publisher upon acceptance.