Numerical modeling of the seasonal circulation in the coastal ocean of the Northern South China Sea

Abstract

The Finite Volume Community Ocean Model (FVCOM) was adapted to the Northern South China Sea (NSCS) to investigate the seasonality of coastal circulation, as well as along-shelf and cross-shelf transport. In fall and winter, southwestward current dominates the NSCS shelf, while the current’s direction shifts to northeast in summer. The circulation pattern in spring is more complicated: both southwestward and northeastward currents are detected on the NSCS shelf. The mean shelf circulation pattern in winter does not show the permanent counter-wind South China Sea Warm Current (SCSWC) along the 100–200 m isobaths. Meanwhile, the model results indicate a northeastward current flowing along 50–100 m isobaths in spring. Southwestward along-shelf transport varies from 0.30–1.93 Sv in fall and winter, and it redirects to northeast in summer ranging from 0.44–1.09 Sv. Onshore transport is mainly through the shelf break segment southeast of the Pearl River Estuary.

Keywords

Northern South China Sea / coastal ocean / seasonal circulation / along-shelf and cross-shelf transport / Ocean model / FVCOM

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Acknowledgements

This work was jointly supported by the National Natural Science Foundation of China (Grant Nos. 41606005, 41676004, 41506027, and 41476047), National Program on Global Change and Air-Sea Interaction (No. GASI–GEOGE 03), National Fund Committee-Shandong joint fund (No. U1706215), the Fundamental Research Funds for the Central Universities (201713023), the Project of State Key Laboratory of Satellite Ocean Environment Dynamics, Second Institute of Oceanography (No. SOEDZZ1805) and the National Key Research and Development Plan (2016YFC1401406 and 2016YFA0600900). All the model simulations are performed in the Ocean Data and Simulation Center of Physical Oceanography Laboratory, Ocean University of China. We thank University of Hawaii Sea Level Center, National Center for Environmental Prediction (NCEP), Hybrid Coordinate Ocean Model, and OSU Tidal Data Inversion for providing valuable data. We also thank the two anonymous reviewers for careful review and constructive comments.

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