强台风纳沙(1117)登陆过程的湍流特性分析

Turbulence Characteristics of the Landing Process of Severe Typhoon Nesat(1117)

利用广东徐闻测风塔观测到的1117号强台风纳沙的三维超声测风数据,采用三维分析法,分析台风在登陆过程的近地层湍流特性,得出以下结论:1)台风风速时程曲线呈明显“M”型双峰分布,台风8级以上大风的风向按顺时针最大连续偏转了219°,台风过程10min最大风速为25.2m/s,0.1s极大风速为36.2m/s;2)台风过程8级以上强风的平均风攻角为0.9°;3)8级大风样本的湍流强度纵向为0.14、横向为0.12、垂直向为0.07,三维方向的湍流强度之比Iu﹕Iv﹕Iw=1﹕0.86﹕0.5;4)8级以上强风的u、v、w三维湍流积分空间尺度平均值分别为132、51、28m;5)台风过境前后的大风区与台风中心的小风区的湍流谱样本均不满足-5/3律和各向同性假设。

Based on the ultrasonic pulse data of the 1117 typhoon Nesat observed in Xuwen,Guangdong,we analyzed the surface layer turbulence characteristics of its landing using the vector analysis method.Results obtained are as follows:1) the wind speed versus time curve of the typhoon showed “M” shape distribution.Direction of wind with velocity greater than 17.2 m/s could be altered up to 219° clockwisely.The 10 min maximum velocity was 25.2 m/s and the 0.1 s maximum velocity was 36.2 m/s. 2) The average wind attack angle with velocity greater than 17.2 m/s was 0.9°.3) Turbulence intensity of the samples with velocity greater than 17.2 m/s was 0.14 longitudinally,0.12 horizontally,and 0.07 vertically,with three-dimensional turbulent intensity ratio being Iu﹕Iv﹕Iw = 1﹕0.86﹕0.5.4) u,v,w three-dimensional turbulence integral scale of the strong wind with velocity greater than 17.2 m/s was 132 m,51 m,28 m,respectively.5) the turbulence spectrum samples of the strong wind before and after typhoon crossing,and the weak wind in the typhoon center,did not meet the -5/3 law and the assumption of isotropy.