Typhoon Wave Forecast In The South Sea By SWAN Model

The exploitation of marine resources has an attractive bright future however, as the development activities of marine resources to new areas, such as deep water and severe natural environment, the conditions of marine operation will be worse, since the wind and waves can do great damage to the exploitation of marine resources. For the design, construction and safe operation of the engineering equipment for offshore oil and gas exploitation in extreme conditions of the South China Sea, forecasting typhoon waves in the South China Sea becomes particularly important. In this paper, the typhoon wave in the South China Sea is simulated and predicted based on the third generation wave model of SWAN.This study has been focused on the influence factors of the accuracy of typhoon wave forecast in the South China Sea by SWAN model based on actual bottom topography and many true typhoon processes. Firstly, comparative analysis has been made on different models of wind fields. Results show that the accuracy of the wind field simulation plays a pivotal role in the typhoon wave forecast. Meanwhile, the study takes into account of all the following factors based on typhoon Kai-tak that could affect results of the typhoon wave simulation in SWAN model:the effect of whitecapping, the diverse combinations of wind input and whitecapping, the refraction term. Some reasonable recommendations have been given after an analysis of these factors respectively. It lets the typhoon waves simulated by SWAN model is more suitable in the South China Sea. The third generation wave model SWAN is employed to simulate typhoon waves which happened in the South China Sea named Super Typhoon Haiyan in2013based on this reasonable recommendations. At the same time, the dynamic change of wave field in the South China Sea is simulated. The result shows that could describe the wave field variance both in the time and space domain as the typhoon go through the South China Sea.The statistical analysis is applied to the tropical storms in65years from1949to2013. Then the tropical storms in the South China Sea, which are up to or beyond the grade of typhoon471in all, are selected to predicted typhoon waves. A database is established that of the extreme wave parameters in South China Sea with the accuracy of0.05°. Return period of the waves can be estimated at any point.Give the extreme value of wave height and average period of65years in the South China Sea. Predict the wave factors once-in-100-years by using P-Ⅲ curve method.At last the characteristics of wave factors of regional value is given.