Statistical Analysis on the Long-Term Observations of Typhoon Waves in the Taiwan Sea

Abstract

Seventeen data buoys were deployed in the Taiwan Sea since 1997. These buoys have made measurement for more than 100 typhoons. The purpose of this paper is to study the statistical characteristics of the observed typhoon waves. High resolution directional wave spectra are obtained by analyzing the buoy data. The Significant Typhoon Wave Height (SWTH) and the Duration of Large Waves (DLW) are proposed to indicate the sea severity of typhoons. The joint effect of the SWTH and the DLW is used to assess possible impact by the typhoon waves to the coast, using the damage curve calibrated from historical events. In addition analysis on the slope of the equilibrium range on the high-frequency side of the typhoon wave frequency spectra shows that its slope is less than 3.5 in absolute value for coastal water and larger than 3.8 for the deep sea. The JONSWAP spectrum model is then used to fit the mean wave spectra of the largest sea state in typhoons. It is found that the peak-enhancement factors  obtained were 2.48 and 2.19 for the deep sea and the coastal ocean, respectively, showing that typhoon waves in Taiwan sea are in the developing stage.