Study On The Typhoon Wind Field Model For Engineering And Its Parametric Test

In recent years,the random numerical method is widely used in typhoon disaster assessment,in which the typhoon wind field model is an important part.However,some parameters have no reliable schemes to the western North Pacific yet,for the study about typhoon wind field model in China is still at the initial stage,and few studies have considered the influence of complex terrain on the simulated wind field.Therefore,it is necessary to study the characteristics of the parameters in typhoon wind field model for engineering,then to find one wind field model suitable for typhoon in the western North Pacific.Based on the observation and research findings of the typhoon boundary layer over the past decade,the empirical expressions of the radius of maximum wind speed,the wind speed ratio and the surface drag coefficient are specified.Then a wind field model applied to the typhoon in the western North Pacific is established according to the vertical mean equation of motion in the boundary layer.In order to verify the rationality of the model,an idealized experiment is performed.And special attention is paid to the sensitivity of the wind field to the parameterization schemes of the surface drag coefficient.Paper also develops a new technique for introducing the drag of terrain into the wind field model to explore the influence of topography on typhoon wind field.The main conclusions are as follows:The typhoon wind field model for engineering we established can well simulate the maximum wind speed and the asymmetric structure of the horizontal wind field.Based on the observation and research findings,we obtained three schemes of drag coefficient.And found that the changes in drag coefficient mainly affect the wind field in the inner core region of strong typhoons.but have no significant impact on the maximum wind speeds.Typhoon HaiKui(No.1211)and ChanHom(No.1509)were simulated and results show that the model can quite well reflect the characteristics of the wind field and the changes in wind speeds and directions.It's also found that the value ofHolland B parameters has a significant effect on the wind field.By introducing the drag of terrain into the typhoon wind field model,the model errors of HaiKui and ChanHom decrease.And the regions with the most significant change are located in the maximum wind area behind the moving direction,in which the speeds decrease and the wind directions rotate clockwise.Results show that,considering the drag of terrain can reflect the characteristics of typhoon wind field more accurately,which could further improves the typhoon disaster assessment.