Variability of the M₂ internal tides in the Luzon Strait under climate change

Internal tides (ITs) radiated from the Luzon Strait (LS) to the South China Sea (SCS) exhibit variability closely related to changes of stratification. Based on the CanESM5 simulation from the sixth phase of Coupled Model Intercomparison Project, the stratification within the LS will increase in the following century due to climate change resulting from human activities. Here we conduct numerical experiments to investigate changes of the M₂ ITs under different shared socioeconomic pathway (SSP) scenarios. Results show that the cumulative generation of ITs within the LS weakens with strengthening stratification. The amount of ITs generated in the LS will decrease by 22.7% (2.7%) and that propagating into the SCS will decrease by 27.9% (4.4%) in a century under the SSP5-8.5 (SSP1-2.6) scenario that represents the high (low) end of future emissions. The changes are attributed to the interference of the M₂ ITs within the double ridges, which weakens as the stratification strengthens and finally reduces the IT generation. Considering that ITs are one of the most important energy sources for diapycnal mixing, the decrease in ITs would have significant physical and biogeochemical implications in the LS and the SCS.