A numerical study of multiscale current effects on waves in the northern South China Sea

Abstract

The current effects on waves (CEW) are of interest owing to their importance for our understanding of wave dynamics. However, there is a lack of research on the effects of multiscale currents on waves in the northern South China Sea. In this study, we conducted a series of process-oriented numerical experiments to quantitatively investigate the characteristics of multiscale currents and their effects on surface waves. The results indicate that the high-resolution simulated currents with tides show more submesoscale processes, where the spatial variability of significant wave height (Hs) at the 10–100 km scale exceeds that in low-resolution simulated currents by a factor of 24 and that in tideless simulated currents by a factor of 39. The divergent component of the surface current dominates the CEW in the northern South China Sea. High-resolution currents induce more refraction of wind waves with shorter wave periods. Furthermore, we investigated the impact of tropical cyclones on the CEW and found that they briefly increase the divergence and relative vorticity of surface currents while temporarily weakening the modulation of submesoscale CEW. This research highlights the importance of submesoscale currents and tidal currents in wave simulations, thus contributing to the improvement of observational and numerical simulation methods.