Journal of Tropical Oceanography ›› 2020, Vol. 39 ›› Issue (3): 1-9.doi: 10.11978/2019086CSTR: 32234.14.2019086

Special Issue: 南海专题

• Marine Hydrology •     Next Articles

Analysis of submesoscale characteristics of summer upwelling fronts in the western South China Sea

Xiaolong HUANG1,2, Zhiyou JING1(), Ruixi ZHENG1,2, Xu ZHANG1,2   

  1. 1. State Key Laboratory of Tropical Oceanography (South China Sea Institute of Oceanology, Chinese Academy of Sciences), Guangzhou 510301, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China;
  • Received:2019-09-12 Revised:2019-12-20 Online:2020-05-10 Published:2020-05-19
  • Contact: Zhiyou JING E-mail:jingzhiyou@scsio.ac.cn
  • Supported by:
    Original Innovation Project of Basic Frontier Scientific Research Program of CAS(ZDBS-LY-DQC011);National Natural Science Foundation of China(41776040);Innovation Academy of South China Sea Ecology and Environmental Engineering, CAS(ISEE2018PY05);Laboratory for Ocean Dynamics and Climate, Pilot Qingdao National Laboratory for Marine Science and Technology(OCFL-201804);Guangzhou Science and Technology Project(201904010420)

Abstract:

We investigate submesoscale characteristics of summer upwelling fronts in the western South China Sea (WSCS) and associated ageostrophic processes by using satellite measurements and high-resolution ROMS simulations. Active submesoscale filaments with a typical horizontal scale of O(1-10) km are detected to be characterized by O(1) Rossby number (Ro) from the fine-resolution satellite images and simulation results. The diagnostic analysis shows that down-front wind forcing drives a net cross-front Ekman transport and advects heavy water over light water. This process at submesoscale tends to reduce the stratification and potential vorticity (PV), exacerbates the frontal instabilities, and forms the cross-front secondary circulation. The high-resolution simulation results show that the maximum vertical velocity in the frontal zone can reach 100m?d -1, which significantly enhances vertical material exchange. In this context, active submesoscale processes may contribute to enhanced vertical exchanges of the upper ocean in the summer upwelling front of the western SCS.

Key words: upwelling front, submesoscale process, ROMS, satellite remote sensing, western South China Sea