Dynamics of the seasonal wave height variability in the South China Sea

Abstract

AbstractWind‐driven ocean surface gravity waves exhibit large fluctuations on multiple scales in both space and time, which greatly impact on air‐sea interactions and human activities in the ocean. The wave height in the South China Sea (SCS) is dominated by the seasonal variability, but the underlying dynamics is poorly understood. Therefore, this study aims to investigate the dynamics of the significant wave height (SWH) seasonality in the SCS using the WAVEWATCH III wave model. The results indicate that the SCS SWH seasonality is dominated by local sea surface winds inside the SCS with a secondary contribution from remote sea surface winds in the tropical western North Pacific Ocean through the propagation of waves. Local sea surface winds alone lead to the SWH maxima occurring in different regions inside the SCS in different seasons. Remote sea surface winds, on the contrary, result in a high SWH tongue extending from the Pacific Ocean into the SCS through the Luzon Strait all year round. They contribute positively to the SCS SWH seasonality, but the contributions are only significant in the northern SCS and decrease westward/southwestward from the Luzon Strait. The SWH in the northern SCS induced by the seasonality of remote sea surface winds is largest in winter while smallest in summer. However, the contribution of remote sea surface winds relative to that of local sea surface winds gets largest in spring, when the local sea surface winds are weakest of the year. The current study emphasizes the importance of sea surface winds in the Pacific Ocean in regulating the SCS SWH seasonality and is helpful for further studies of the dynamics and predictions of wave climate variabilities on multiple time scales in the SCS.