A numerical study of the South China Sea Warm Current during winter monsoon relaxation -- Journal of Oceanology and Limnology,2018,36(2):216-229

	Cite this paper:
	ZHANG Cong, DING Yang, BAO Xianwen, BI Congcong, LI Ruixiang, ZHANG Cunjie, SHEN Biao, WAN Kai. A numerical study of the South China Sea Warm Current during winter monsoon relaxation[J]. Journal of Oceanology and Limnology, 2018, 36(2): 216-229

A numerical study of the South China Sea Warm Current during winter monsoon relaxation

ZHANG Cong^1,2, DING Yang², BAO Xianwen^1,2, BI Congcong^1,2, LI Ruixiang³, ZHANG Cunjie^1,2, SHEN Biao², WAN Kai⁴

1 College of Oceanic and Atmospheric Sciences, Ocean University of China, Qingdao 266100, China;
2 Key Laboratory of Physical Oceanography, Ministry of Education, Ocean University of China, Qingdao 266100, China;
3 South China Sea Marine Survey and Technology Center, State Ocean Administration, Guangzhou 510310, China;
4 Beihai Offshore Engineering Survey Institute, State Oceanic Administration, Qingdao 266061, China

Abstract:

Using a Finite-Volume Community Ocean Model, we investigated the dynamic mechanism of the South China Sea Warm Current (SCSWC) in the northern South China Sea (NSCS) during winter monsoon relaxation. The model reproduces the mean surface circulation of the NSCS during winter, while model-simulated subtidal currents generally capture its current pattern. The model shows that the current over the continental shelf is generally southwestward, under a strong winter monsoon condition, but a northeastward counter-wind current usually develops between 50-and 100-m isobaths, when the monsoon relaxes. Model experiments, focusing on the wind relaxation process, show that sea level is elevated in the northwestern South China Sea (SCS), related to the persistent northeasterly monsoon. Following wind relaxation, a high sea level band builds up along the mid-shelf, and a northeastward current develops, having an obvious vertical barotropic structure. Momentum balance analysis indicates that an along-shelf pressure gradient provides the initial driving force for the SCSWC during the first few days following wind relaxation. The SCSWC subsequently reaches a steady quasi-geostrophic balance in the cross-shelf direction, mainly linked to sea level adjustment over the shelf. Lagrangian particle tracking experiments show that both the southwestward coastal current and slope current contribute to the northeastward movement of the SCSWC during winter monsoon relaxation.

Received: 2016-11-17 Revised:

Tools

PDF (3050 KB) Free

Print this page

Add to favorites

Email this article to others

Authors

Articles by ZHANG Cong

Articles by DING Yang

Articles by BAO Xianwen

Articles by BI Congcong

Articles by LI Ruixiang

Articles by ZHANG Cunjie

Articles by SHEN Biao

Articles by WAN Kai

References:
Centurioni L R, Niiler P N, Lee D K. 2009. Near-surface circulation in the South China Sea during the winter monsoon. Geophys. Res. Lett., 36(6):L06605, https://doi.org/10.1029/2008GL037076.
Chao S Y, Shaw P T, Wang J. 1995. Wind relaxation as possible cause of the South China Sea Warm Current. J. Oceanogr., 51(1):111-132.
Chen K, He R. 2015. Mean circulation in the coastal ocean off northeastern North America from a regional-scale ocean model. Ocean. Sci., 11(4):503-517, https://dx.doi.org/10.5194/os-11-503-2015.
Chiang T L, Wu C R, Chao S Y. 2008. Physical and geographical origins of the South China Sea Warm Current. J. Geophys.Res., 113(C8):C08028, https://doi.org/10.1029/2008JC004794.
Chu P C, Fan C W, Lozano C J, Kerling J L. 1998. An airborne expendable bathythermograph survey of the South China Sea, May 1995. J. Geophys. Res., 103(C10):21 637-21 652.
Fang G H, Zhao B R. 1988. A note on the main forcing of the northeastward flowing current off the Southeast China Coast. Progress in Oceanography, 21(3):363-372.
Guan B X, Chen S J. 1964. The Current Systems in the Nearsea Area of China Seas. Initial Report 5. Institute of Oceanology, Chinese Academy of Sciences, Qingdao, China. p.1-85. (in Chinese)
Guan B X, Fang G H. 2006. Winter counter-wind currents off the southeastern China coast:a review. J. Oceanogr., 62(1):1-24.
Guan B X. 1978. The warm current in the South China Sea-a current flowing against the wind in winter in the open sea off Guangdong Province. Oceanol. Limnol. Sin., 9(2):117-127. (in Chinese with English abstract)
Guan B X. 1985. Some features of the temporal and spatial distributions of the "counter-wind" current in northern South China Sea in winter. Oceanol. Limnol. Sin., 16(6):429-438. (in Chinese with English abstract)
Guan B X. 1986. Evidence for a counter-wind current in winter off the southeast coast of China. Chin. J. Oceanol.Limnol., 4(4):319-332.
Guan B X. 2002. Winter Counter-Wind Current off the Southeastern China Coast. China Ocean University Press, Qingdao, China. 267p. (in Chinese)
Guo Z X, Yang T H, Qiu D Z. 1985. The South China Sea warm current and the SW-ward current on its right side in winter. Tropical Oceanology, 4(1):1-9. (in Chinese with English abstract)
He Q, Wei Z X, Wang Y G. 2012. Study on the sea currents in the northern shelf and slope of the South China Sea based on the observation. Acta. Oceanol. Sin., 34(1):17-28. (in Chinese with English abstract)
Hong B, Wang D X. 2006. Diagnostic analysis on the northern South China Sea winter counter-wind current. Chinese Science Bulletin, 51(2):9-16.
Hsueh Y, Zhong L J. 2004. A pressure-driven South China Sea warm current. J. Geophys. Res., 109(C9):C09014, https://doi.org/10.1029/2004JC002374.
Li L, Nowlin Jr W D, Su J L. 1998. Anticyclonic rings from the Kuroshio in the South China Sea. Deep Sea Res. I, 45(9):1 469-1 482.
Li R X, Chen C S, Xia H Y, Beardsley R C, Shi M C, Lai Z G, Lin H C, Feng Y Q, Liu C J, Xu Q C, Ding Y, Zhang Y. 2014. Observed wintertime tidal and subtidal currents over the continental shelf in the northern South China Sea.J. Geophys. Res., 119(8):5 289-5 310, https://doi.org/10.1002/2014JC009931.
Mellor G L, Yamada T. 1982. Development of a turbulence closure model for geophysical fluid problems. Rev.Geophys., 20(4):851-875.
Smagorinsky J. 1963. General circulation experiments with the primitive equations:I. The basic experiment. Mon.Wea. Rev., 91(3):99-164.
Su J L, Liu X B. 1992. Numerical simulation of circulation in the South China Sea. In:Zeng Q C ed. Proceedings of Symposium on Ocean Circulation. China Ocean Press, Beijing, China. p.206-215. (in Chinese)
Su J L, Wang W. 1987. On the sources of the Taiwan warm current from the South China Sea. Chin. J. Oceanol.Limnol., 5(4):299-308.
Su J Z, Lu J, Hou Y J, fang G H, Wei Z X, Yin B S. 2002.Analysis of satellite-tracked drifting buoys in the South China Sea. Oceanol. Limnol. Sin., 33(2):121-127. (in Chinese with English abstract)
U.S. Naval Oceanographic Office and the U.S. 1983. Naval Ocean Research and Development Activity. DBDB5(Digital Bathymetric Data Base-5 Minute Grid). U. S.Naval Oceanographic Office, Bay St. Louis. 329p.
Wang D X, Hong B, Gan J P, Xu H Z. 2010. Numerical investigation on propulsion of the counter-wind current in the northern South China Sea in winter. Deep Sea Res. I, 57(10):1 206-1 221.
Wang D X, Xu H Z, Lin J, Hu J Y. 2008. Anticyclonic eddies in the northeastern South China Sea during winter 2003/2004. J. Oceanogr., 64(6):925-935, https://doi.org/10.1007/s10872-008-0076-3.
Wang K, Fang G H, Shi X H. 2001. Numerical study on the formation of the South China Sea Warm Current Ⅱ.Baroclinic Case. Chin. J. Oceanol. Limnol., 19(4):306-311.
Wang K, Fang Y. 2001. Numerical study on the formation of the South China Sea warm current I. Barotropic case.Chin. J. Oceanol. Limnol., 19(1):1-9.
Wang Q, Wang Y X, Bo H, Zhou W D, Wang D X. 2011.Different roles of Ekman pumping in the west and east segments of the South China Sea Warm Current. Acta.Oceanol. Sin., 30(3):1-13.
Wyrtki K. 1961. Physical oceanography of the Southeast Asian water. In:Wyrtki K ed. NAGA Report:Scientific Result of Marine Investigation of the South China Sea and Gulf of Thailand 1959-1961. Scripps Institution of Oceanography, California, United States. p.155-160.
Xie J P, Zhu J. 2008. Estimation of the surface and mid-depth currents from Argo floats in the pacific and error analysis.J. Mar. Syst., 73(1-2):61-75.
Xie J P, Zhu J. 2009. A dataset of global ocean surface currents for 1999-2007 derived from Argo float trajectories:a comparison with Surface Drifter and TAO measurements.Atmos. Ocean. Sci. Lett., 2(2):97-102.
Xiong X J. 2013. The circulation structure and mechanism studies on the China Seas. Ocean University of China, Qingdao, China. 208p. (in Chinese)
Xue H J, Chai F, Pettigrew N, Xu D Y, Shi M C, Xu J P. 2004.Kuroshio intrusion and the circulation in the South China Sea. J. Geophys. Res., 109(C2):C02017, https://doi.org/10.1029/2002JC001724.
Yang J Y, Wu D X, Lin X P. 2008. On the dynamics of the South China Sea warm current. J. Geophys. Res., 113(C8):C08003, https://doi.org/10.1029/2007JC004427.
Yang K C. 2006. The non-persistent South China Sea warm current. National Taiwan University, Taipei, China. 49p.
Yuan D L, Han W Q, Hu D X. 2007. Anti-cyclonic eddies northwest of Luzon in summer-fall observed by satellite altimeters. Geophys. Res. Lett., 34(13):L13610, https://doi.org/10.1029/2007GL029401.
Zeng X Z, Peng S Q, Li Z J, Qi Y Q, Chen R Y. 2014. A reanalysis dataset of the South China Sea. Sci. Data., 1:140052. https://doi.org/10.1038/sdata.2014.52.
Zhong H L. 1990. Structures of the density circulation. In:Ma Y L ed. Report of Decadal Hydrographic Series Survey of the Shelf and Adjacent Waters of the Northern South China Sea. China Ocean Press, Beijing, China. p.215-241.(in Chinese)