Study On Characteristics Of Strong Typhoon And Monsoon Profiles And Prediction Of Extreme Wind Speed In Coastal Areas

The southeastern coastal areas of China are the most significantly affected areas by typhoons and monsoons.Many cities in coastal areas have become high-risk areas for typhoon disasters due to their location on the Pacific storm path.At the same time,the region is also a typical monsoon climate zone,and due to the instability of the monsoon,various monsoon disasters may occur in different seasons.The direct effect of disastrous gales will lead to the destruction of low buildings and serious damage to high-rise structures.Therefore,a comprehensive understanding of the characteristics of strong typhoons and monsoon profiles in coastal areas and reasonable structural wind resistance design will greatly reduce property losses and casualties caused by wind disasters in coastal areas.Based on the measured wind data of different typical coastal cities,this paper firstly systematically studied the variation characteristics of the boundary layer profile of super typhoons in coastal areas and then summarized the statistical characteristics of the wind field in typical monsoon climate areas by statistical analysis method.Finally,based on the short-term measured monthly extreme wind speed,the annual extreme wind speed distribution in this region is fitted to obtain the measured basic wind pressure in this region through calculation.The main research contents and conclusions are as follows:(1)Analysis of typical super typhoon outer layer wind profile development features.The characteristics of the wind velocity fluctuation profile and the wind direction profile change were discovered through the study of the characteristics of the wind field development during the passing of super typhoon Lekima.The study demonstrates that a variety of factors,including different typhoon stages,varying wind speed intervals,incoming wind direction,and average time interval,have an impact on the wind profile.The common wind profile model is only applicable to the wind profile from the bottom of the typhoon to the altitude of low-level jet.(2)Study on statistical characteristics of wind field in typical coastal monsoon climate regions.Based on the measured data of two stations,the evolution characteristics of mean wind speed and wind direction in different seasons in the monsoon climate region are summarized.The results show that the maximum monthly wind speed is more than10 m/s in the monsoon climate area.The dominant wind direction is different in different seasons,and the prevailing wind direction of summer monsoon is easterly.Annual extreme wind speed often occurs in the summer and autumn typhoon months.In addition,the phenomenon of low-level jet still exists in monsoon,and the frequency is higher at night than in the daytime.(3)Comparative study on the distribution characteristics of mean winds between typhoons and normal monsoons.The results show that the wind speed of typhoon is evenly distributed,the overall wind speed is greater than that of good monsoon,and the measured wind direction angle of typhoon is bimodal distribution;The measured average wind speed of normal monsoon is long tail distribution,and the wind direction angle is weak bimodal distribution.In addition,based on actual measurements,a total of 5 forms of typhoon and monsoon wind speed profiles have been summarized in coastal areas.(4)Distribution of extreme wind speed and basic wind pressure in different recurrence periods in typical coastal areas.It is found that the monthly extreme wind speed distribution is unimodal left skewed by using extreme I distribution,Weibull distribution,and kernel density estimation.The kernel density estimation fits the monthly extreme wind speed distribution well,while the extreme value I distribution and Weibull distribution are closer to the actual wind speed distribution when the wind speed sample value is less than 19 m/s.By converting the measured extreme wind speed and the extreme wind speed obtained by other scholars through random simulation of typhoon into basic wind pressure,and comparing with the norms,it is found that the measured basic wind pressure is relatively small,while the basic wind pressure obtained by random simulation of typhoon is relatively large.