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Journal of Oceanology and Limnology

, Volume 36, Issue 2, pp 216–229 | Cite as

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

  • Cong Zhang (张丛)
  • Yang Ding (丁扬)
  • Xianwen Bao (鲍献文)
  • Congcong Bi (毕聪聪)
  • Ruixiang Li (李锐祥)
  • Cunjie Zhang (张存杰)
  • Biao Shen (沈飙)
  • Kai Wan (万凯)
Physics
  • 123 Downloads

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.

Keyword

northern South China Sea South China Sea Warm Current monsoon relaxation numerical model pressure gradient barotropic structure 

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Notes

Acknowledgement

We thank the Ocean University of China’s Physical Oceanography Laboratory Ocean Data and Simulation Center for providing the hardware support. We also thank Asia-Pacific Data-Research Center (APDRC) of the International Pacific research Center, Center for Earth Information Science and Technology (CEIST), Geophysical Fluid Simulation Research Group (GFSG), NASA’s Making Earth Science data records for Use in Research Environments (MEaSUREs) Program, NOAA’s National Center for Environmental Information (NCEI), and the China Argo Real-time Data Center for providing valuable data for this study.

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Copyright information

© Chinese Society for Oceanology and Limnology, Science Press and Springer-Verlag GmbH Germany, part of Springer Nature 2017

Authors and Affiliations

  • Cong Zhang (张丛)
    • 1
    • 2
  • Yang Ding (丁扬)
    • 2
  • Xianwen Bao (鲍献文)
    • 1
    • 2
  • Congcong Bi (毕聪聪)
    • 1
    • 2
  • Ruixiang Li (李锐祥)
    • 3
  • Cunjie Zhang (张存杰)
    • 1
    • 2
  • Biao Shen (沈飙)
    • 2
  • Kai Wan (万凯)
    • 4
  1. 1.College of Oceanic and Atmospheric SciencesOcean University of ChinaQingdaoChina
  2. 2.Key Laboratory of Physical Oceanography, Ministry of EducationOcean University of ChinaQingdaoChina
  3. 3.South China Sea Marine Survey and Technology CenterState Ocean AdministrationGuangzhouChina
  4. 4.Beihai Offshore Engineering Survey InstituteState Oceanic AdministrationQingdaoChina

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