上海地区近地台风实测分析

Field measurement of typhoon characteristics near ground in Shanghai district

基于10 m、20 m、30 m和40 m高度处台风"梅花"影响下的上海浦东地区近地风实测数据,对平均风速与风向、阵风因子随阵风持续时距的变化、脉动风速分量的概率分布及其之间相关性进行了分析。研究结果表明:10m高度处,12m/s以上时段纵向阵风因子随阵风持续时距变化的曲线与Durst曲线较为符合,而12m/s以下时段实测曲线与Krayer-Marshall曲线基本符合;当阵风持续时距小于某一临界值时,10 m高度处横向和竖向阵风因子较20 m和40 m处的结果明显偏大,而大于此临界值后,三者较为接近,横向和竖向对应的临界值分别约为100 s和10 s;不同时段及高度处各向脉动风速分量均服从高斯分布;纵向与横向脉动风速自相关系数的衰减速率随实测高度的增大而减小,并通过拟合给出了相应的经验表达式;脉动风速分量之间互相关系数随平均风速的变化趋势不明显。

Here,the wind characteristics of typhoon Muifa＇,such as,wind speed,wind direction,variations of gust factors with gust averaging time,probability distribution of fluctuating wind speed,auto-correlation curves and cross-correlation coefficients between wind speed fluctuation components were discussed on the basis of long time measured data recorded respectively at the height of 10m,20m,30m and 40m above the ground in Pudong,Shanghai.It was shown that for low-wind-speed regime（U12m/s）,the observed values of longitudinal gust factor for different gust averaging time are consistent with those proposed by Krayer-Marshall,but agree well with those proposed by Durst for high-wind-speed regime（U12m/s）;the estimated values of gust factors for lateral and vertical fluctuation components at the observation height of 10m are significantly larger than those at the observation height of 20m and 40m when the gust averaging time is less than 100s and 10s,respectively;the probability density function of fluctuation wind speed of this typhoon follows a Gaussian distribution;the decay rate of auto-correlation curves for longitudinal and lateral fluctuation components decrease with increase in observation heights,and the empirical formulas are also obtained using least-square technique;cross-correlation coefficients stay almost constant when wind speed becomes high.