Long-Term Variability of Extreme Significant Wave Height in the South China Sea

Abstract EN

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.