Numerical Simulation Of Typhoon Waves In Northwest Pacific Ocean

Northwest of Pacific Ocean is the most active area of tropical cyclones in the world,and around one third of the tropical cyclones occur in this area every year. The stormy waves and swells caused by typhoon have significant impact on navigation, harbor and offshore engineering. In this paper, the typhoon 9711(Winnie)and 0008 (Jelawat) which affected the East China Sea in 1997 and 2000 are described, and the storm waves induced by the typhoon Winnie and Jelawat are hindcasted. The parameter typhoon wind model (PTWM) is derived from Jelesnianski2 wind formula and Fujita pressure formula (FPF), compounded with NCAR background wind field, hindcast the wind formula ; while the third-generation deep-sea wave model (WAVEWATCH III) are applied to hindcast the storm wavesFirst of all, the Maximum wind speed radius is one of the most important parameter in the wind formula .However, it can not be obtained from the typhoon parameters of the weather station, thus it is substituted by the maximum wind speed or the radius of gale cycle, etc. In this paper, the maximum wind speed radius is calculated by experiential formula(MEF) and retrieved from gale cycle (MGCR) .The wind field model is composed by PTWM and background wind date from NECP.Secondly, typhoon wave is calculated by third-generation ocean wave model (WAVEWATCH III). The sea-bottom dates are obtained from nautical charts digitized by the digitized instrument, interpolated and integrated with the United States and the world's underwater topography information on the Northwest Pacific Ocean. Considering typhoon is a large-scale atmospheric system, latitude and longitude grid model is used, and the size of mesh is 0.2×0.2, 201×201 meshes in all. In view of the deep depth of the water, the bottom of the friction, the trend, ice and other factors can be ignored, so that the calculation is simple and fast. Computing time step is 15 minutes and the results are output per hour.Finally, the above model are used to simulate the "9711" Typhoon (Winnie).The comparisons between the simulation results and observation data indicate that: during the typhoon Winnie and Jelawat, the distribution of modeled storm-waves in Northwest Pacific Ocean, which is simulated by MEF is more reasonable. Comparing the significant wave height calculated and measurements in three offshore stations, the error is about 10%, and it shows that MEF is better than MGCR. So the modeled results, which are derived from compound wind field and third-generation ocean wave model (WAVEWATCH III), can serve for scientific reference of naval architecture, ocean engineering, and coastal engineering.