Long-term variability of extreme significant wave height in the South China Sea

Abstract

This paper describes long-term spatiotemporal trends in extreme significant wave height (SWH) in the South China Sea (SCS) based on 30-year wave hindcast. High-resolution reanalysis wind field data sets are employed to drive a spectral wave model WAVEWATCH III™ (WW3). The wave hindcast information is validated using altimeter wave information (Topex/Poseidon). The model performance is satisfactory. Subsequently, the trends in yearly/seasonal/monthly mean extreme SWH are analyzed. Results showed that trends greater than 0.05 m yr-1 are distributed over a large part of the central SCS. During winter, strong positive trends (0.07-0.08 m yr-1) are found in the extreme northeast SCS. Significant trends greater than 0.01 m yr-1 are distributed over most parts of the central SCS in spring. In summer, significant increasing trends (0.01-0.05 m yr-1) are distributed over most regions below latitude 16°N. During autumn, strong positive trends between 0.02 and 0.08 m yr-1 are found in small regions above latitude 12°N. Increasing positive trends are found to be generally significant in the central SCS in December, February, March, and July. Furthermore, temporal trend analysis showed that the extreme SWH exhibits a significant increasing trend of 0.011 m yr-1. The extreme SWH exhibits the strongest increasing trend of 0.03 m yr-1 in winter and showed a decreasing trend of -0.0098 m yr-1 in autumn.