Abstract. The South China Sea (SCS) is the largest marginal sea in the northwest Pacific Ocean. In this study, deep circulation in the SCS is investigated using results from eddy-resolving, regional simulations using the Hybrid Coordinate Ocean Model (HYCOM) verified by continuous current-meter observations. Analysis of these results provides a detailed spatial structure and temporal variability of the deep circulation in the SCS. The major features of the SCS deep circulation are a basin-scale cyclonic gyre and a concentrated deep western boundary current (DWBC). Transport of the DWBC is ∼ 2 Sv at 16.5° N with a width of ∼53 km. Flowing southwestward, the narrow DWBC becomes weaker with a wider range. The model results reveal the existence of 80- to 120-day oscillation in the deep northeastern circulation and the DWBC, which are also the areas with elevated eddy kinetic energy. This intraseasonal oscillation propagates northwestward with a velocity amplitude of ∼ 1.0 to 1.5 cm s-1. The distribution of mixing parameters in the deep SCS plays a role in both spatial structure and volume transport of the deep circulation. Compared with the northern shelf of the SCS with the Luzon Strait, deep circulation in the SCS is more sensitive to the large vertical mixing parameters of the Zhongsha Island Chain area.
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North China Sea Marine Forecasting Center, State Oceanic Administration, Qingdao, 266061, P. R. China
Key Laboratory of Physical Oceanography/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, P. R. China
Chun Zhou
Key Laboratory of Physical Oceanography/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, P. R. China
Center for Ocean-Atmospheric Prediction Studies (COAPS), Florida State University, Tallahassee, FL, USA
Ruijie Ye
Key Laboratory of Physical Oceanography/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, P. R. China
Jiwei Tian
Key Laboratory of Physical Oceanography/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, P. R. China
Wei Zhao
Key Laboratory of Physical Oceanography/CIMST, Ocean University of China and Qingdao National Laboratory for Marine Science and Technology, Qingdao 266100, P. R. China
This study presents a detailed spatial structure and temporal variability of the deep circulation under enhanced mixing in the South China Sea (SCS) based on eddy-resolving model simulations verified by continuous current-meter observations and enables us to investigate sensitivity to distribution of mixing. Comparing the northern shelf of the SCS with the Luzon Strait, deep circulation in the SCS is more sensitive to the large vertical mixing parameters in the Zhongsha Island Chain area.
This study presents a detailed spatial structure and temporal variability of the deep...