Researh On The Northern South China Sea Wave Spectrum Under The Influence Of Typhoon

In this paper, we focus the research on the spectrum of northern South China Sea. Three issues are studied, the ocean wave spectrum for ordinary sea conditions, the ocean wave spectrum for high sea conditions and the numeric simulation of wave under the influence of typhoon.First, according to the data measured by Wave Rider which was put in the position of 115.13°E, 21.89°N, we give the wave spectrum of the northern South China Sea under ordinary sea conditions. Then we fit the growth relationship between spectrum parameters and wind parameters and revise the former growth relationship.Then, according to the data measured by Wave Rider which was put in the position of 115.13°E 21.89°N, we give the spectrum during three typhoons passage-Conson, Chanthu, and Megi in 2010. We study the changing process during typhoons passage. Then the typhoon wave spectrum is fitted by the form of JONSWAP spectrum. The results show that the typhoon wave spectrum can be well fitted by JONSWAP spectrum. We import a parameter--spectrum width B to JONSWAP spectrum and calculate the relationship between and B. So we can choose different to fit different typhoons’ wave spectrum by means of calculating spectrum width B. The fetch limited relationship between spectrum parameters and dimensionless fetch, wave parameters and fetch are also discussed. In addition, we extract wave parameters from spectrum and calculate the dependence relationship between significant wave height, average period and dimensionless fetch.Finally, we simulate the wave spectrum of northern South China Sea by SWAN when typhoon Megi was passing. We analyze the spectrum data outputted by SWAN model and get the dependence relationship between spectrum parameters and dimensionless fetch.