Influence of Remote Internal Tides on the Locally Generated Internal Tides upon the Continental Slope in the South China Sea

Zheng Guo,Shuya Wang,Anzhou Cao

doi:10.3390/jmse9111268

Abstract

In this paper, the M2 internal tides (ITs) originating from the continental slope in the South China Sea are studied using the CROCO model. The simulation results show that there are two origins of ITs on the continental slope: at 118°–119.5° E along 22° N near the southern entrance of the Taiwan Strait and at 117°–118° E along 20° N near Dongsha Island. The local generation of ITs is greatly influenced by the ITs that radiate from the Luzon Strait (LS). The integrated conversion at the first generation site is increased by 31% to 0.42 GW compared to the case where the LS is excluded from the simulation region. Its maximum energy flux almost doubles to 2.5 kW/m, which is 10% of the westward component. The existence of the other IT beams from Dongsha Island is attributed to the ITs from the LS. The local generation on the continental slope changes when remotely generated ITs alter the amplitudes and phases of the bottom pressure perturbation. These results indicate that the ITs originating from the LS contribute to the spatial variation of ITs in the SCS by modulating the IT generation on the continental slope.

Highlights

The internal tide (IT) is an important intermediate step of the tides-to-turbulence cascade, which connects large- and small-scale motions
The results indicate that the ITs remotely generated at the Luzon Strait (LS) have a major influence on those originating from the continental slope
Based on the Coastal and Regional Ocean COmmunity (CROCO), the current study explores the M2 IT generation on the continental slope in the SouthChina Sea (SCS)

Summary

Introduction

The internal tide (IT) is an important intermediate step of the tides-to-turbulence cascade, which connects large- and small-scale motions. It plays an important role in the dissipation of surface tidal energy and the enhancement of mixing. The authors of [9] revealed a number of generation sites in the simulation of the M2 ITs in the Western Pacific, including the southern Taiwan Strait, which was confirmed in later studies [8,10,11], yet the ITs generated at the LS were so intense that they attracted the most attention and obscured weaker ITs generated at other sites

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