Journal of Tropical Oceanography ›› 2021, Vol. 40 ›› Issue (5): 10-24.doi: 10.11978/2020116CSTR: 32234.14.2020116

• Marine Physics • Previous Articles     Next Articles

Spatial and seasonal differences of the upper-ocean submesoscale processes in the South China Sea

YANG Xiaoxiao1(), CAO Haijin1(), JING Zhiyou2   

  1. 1. College of Oceanography, Hohai University, Nanjing 210024, China
    2. State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology, Chinese Academy of Sciences), Guangzhou 510301, China
  • Received:2020-09-30 Revised:2021-03-05 Online:2021-09-10 Published:2021-03-15
  • Contact: CAO Haijin E-mail:181311010026@hhu.edu.cn;h.cao@hhu.edu.cn
  • Supported by:
    National Key Research and Development Program of China(2017YFA0604104);Opening Foundation of State Key Laboratory of Tropical Oceanography(South China Sea Institute of Oceanology)(LTO1907);Chinese Postdoctoral Foundation(2018M642148);Jiangsu Planned Projects for Postdoctoral Research Funds(2018K149C);National Natural Science Foundation of China(41776040);Laboratory for Ocean Dynamics and Climate, Pilot Qingdao National Laboratory for Marine Science and Technology(OCFL-201804)

Abstract:

The South China Sea (SCS) is the largest marginal sea in the western Pacific Ocean. Due to the significant monsoons and the impact of the Kuroshio intrusion via the Luzon Strait, the local dynamic environment is complicated. Thus, the submesoscale behaviors in the SCS show clear spatial and temporal differences. In this paper, based on the outputs of a high-resolution numerical model, we examine the spatial and seasonal differences of submesoscale processes, influence depth and possible influencing factors in different sub-regions (the northern SCS, the central SCS basin, the western SCS, and the southern SCS). We find that the seasonal variation and mechanisms in each region is unique: The northern part is affected by the winter monsoon and the intrusion of the Kuroshio obviously, so that the mixed layer instability (MSI) is strong; and the submesoscale processes (SMPs) are active in winter. The SMPs in the central basin also shows stronger in winter and weaker in summer. The enhanced summer SMPs in the western SCS are attributed to the summer monsoon. The multi-island topography in the southern SCS generates great submesoscale wake eddies, which do not show significant seasonality.Statistical analysis shows that submesoscale processes tend to be associated with strong positive relative vorticity and high strain; in contrast, negative values of potential vorticity are more likelyto appear in the surface layer with poor fluid stability. Furthermore, we discuss the main energy sources and control factors of SMPs by analyzing their energetics.

Key words: South China Sea, submesoscale, seasonal variation, upper ocean, spatial difference

CLC Number: 

  • P731.27