92 / 2023-07-29 19:35:26

Submesoscale processes in the western boundary current of South China Sea

submesoscale,western boundary current

The western boundary current (WBC) of South China Sea (SCS) flows along the northern continental shelf of the SCS and Indochina Peninsula, which has distinct seasonal characteristics, southward in winter and northward in summer. Previous studies revealed that the seasonal variations of the wind field mainly account for the seasonal variations of the WBC by low-resolution simulations (Yang H J et al., 2002; Fang G H et al., 2009). But these simulations generally underestimate the volume transport and time variation of the WBC compared with observational results (Li L. et al., 2018). A high-resolution simulation based on the Regional Oceanic Modeling System (ROMS) with nesting is employed in this study and the results reveal massive submesoscale processes in this area.  The summer submesoscale processes are associated with frontogenesis and the winter submesoscale processes are associated with eddies. These processes play important roles in the enhanced horizontal volume transport and vertical exchanges (e.g., heat, nutrients, and carbon), as well as energy transfer to smaller scales. Meanwhile, the runoff of Mekong River and the effect of shore tides cannot be neglected in this area. So, a series of sensitivity simulations are carried out to figure out the influences of runoff and tides on the WBC of SCS. By comparisons, the results suggest complex interaction processes in this area, and more studies are needed to find out the mechanisms among these dynamical processes.



References

Fang G H，Wang Y G,Wei ZX， et al. Interocean circulation and heat and freshwater budgets of the South China Sea based on a numerical model[J]. Dynamics of Atmospheres and Oceans，2009,47:55-72.

Li, L., Guo, X. & Wu, R. The winter western boundary current of the South China Sea: physical structure and volume transport in December 1998. Acta Oceanol. Sin. 37, 1–7 (2018). https://doi.org/10.1007/s13131-018-1195-3

Yang H J, Liu Q Y, Liu Z Y , et al. A general circulation model studly of the dynamics of the upper ocean circulation of the South China Sea[J]. Journal of Geophysical Research，2002,107:22.