Statistical analyses of sea state conditions in South China Sea

Abstract

The statistical characterization of sea conditions in the South China Sea (SCS) was investigated by analyzing a 30-year (1976–2005) numerically simulated daily wave height and wind speed data. The monthly variation of these parameters shows that wave height and wind speed have minimum values of 0.54 m and 4.15 m s−1, respectively in May and peak values of 2.04 m and 8.12 m s−1, respectively in December. Statistical analysis of the daily wave height and wind speed and the subsequent characterization of the annual, seasonal and monthly mean sea state based on these parameters were also done. Results showed that, in general, the slight sea state prevails in the SCS and has nearly the highest occurrence in all seasons and months. The moderate sea condition prevails in the winter months of December and January while the smooth (wavelets) sea state prevails in May. Furthermore, spatial variation of sea states showed that calm and smooth sea conditions have high occurrences (25%–80%) in the southern SCS. The slight sea condition shows the largest occurrence (25%–55%) over most parts of the SCS. High occurrences (8%–17%) of the rough and very rough seas distribute over some regions in the central SCS. Sea states from high to phenomenal conditions show rare occurrence (<12%) in the northern SCS. The calm (glassy) sea condition shows no occurrence in the SCS.