基于测风塔实测台风威马逊登陆过程的强风特性分析

Analysis on Severe Wind Characteristics During Typhoon Rammasun Landing Process Based on the Observation at Wind Tower

利用广东省徐闻县西连镇90 m测风塔在1409号超强台风威马逊登陆期间获取的具备完整的台风代表性的观测数据以及处于台风外围的广东省茂名市博贺镇100 m测风塔的观测数据,对台风威马逊的近地层强风特性进行了分析,西连测风塔结果表明:风速时程曲线呈明显的"M"型分布特征,台风中心经过测风塔前后,风向沿逆时针方向大幅偏转约170°。风速随高度增加而增大,风速廓线较好地符合对数和幂指数律;台风过境前后,各强风区的风速廓线幂指数和粗糙长度呈先减小后增大的特点;粗糙陆地下垫面的风速廓线幂指数和粗糙长度较大。湍流强度和阵风系数在前外围强风区或后外围强风区较大,在前眼壁强风区或后眼壁强风区较小,湍流强度和阵风系数随高度增加而减小,基本符合指数为负值的幂指数律;粗糙下垫面对湍流强度和阵风系数有增大的作用。外围强风区和眼壁强风区的10 min风向变率变化较为平稳,而在眼区变动较为剧烈,在眼区,当风速达到最低值或次低值时,10 min风向变率幅值达到最大值。博贺测风塔结果表明其总体上与西连测风塔台风前外围和前眼壁强风区的情形相似。

Based on the representative observation data obtained by the 90 m wind tower in Xilian Town,Xuwen County,Guangdong Province during the landfall of No.1409 Super Typhoon Rammasun,and the observation data of 100 m wind tower in Bohe Town,Maoming City,Guangdong Province,which is located in the periphery of the typhoon,the characteristics of the severe winds near surface layer are analyzed.The results of Xilian Tower show that time variations of the wind speed present clear“M”pattern.The wind direction counterclockwise deflects about 170°as the typhoon center passes through the tower.The wind speed increases with the increase of height,and the wind speed profile fits well with the laws of logarithm and power index.Wind shear index and roughness length decrease first and then gradually increase during the typhoon passing period.The wind shear index and roughness length on rough land underlying surface are large.The turbulence intensity and gust coefficient are larger in the front or back outer-vortex,but smaller in the front or back eye-wall.The turbulence intensity and gust coefficient decrease with the increase of height,which basically accords with the power law with negative exponent.The turbulence intensity and the gust coefficient are amplified under the influence of the rough underlying surface.The variation of the 10 min wind direction is more stable in the outer-vortex and eye-wall compared with that in wind eye in which it is rather intense.The maximum amplitude of the 10 min wind direction occurred when the wind speed reaches the minimum in the typhoon eye.The results of the Bohe Tower show that the situation is similar to that of the Xilian Tower when it is located in the front outer-vortex and the front eye-wall of the typhoon.