基于测风激光雷达的沿海架空输电线路台风观测方法

为研究台风近地层风场的时空变化特征,积累台风期间沿海架空输电线路杆塔的现场风速资料,本文利用国产某扫描型测风激光雷达,开展了1604号强台风“妮妲”登陆期间的局地风场观测。根据雷达风廓线扫描与低仰角水平方位扫描数据反演与分析,验证了沿海输电线路台风观测采用测风激光雷达的适用性。研究结果表明:台风“妮妲”眼区经过观测点所形成的气压时间变化呈现典型的“U”形曲线形态。台风眼壁强风区经过观测点所形成的风速时间变化呈现较为典型的“双峰形”曲线形态。台风眼壁强风区与眼区的风速、风向、阵风系数等随高度的变化差异明显。风速廓线在300 m高度以上明显偏离指数律或对数律廓线形式;受地转效应影响,风向随高度增加出现一定幅度的向右偏转;阵风系数随高度增加、平均风速增大出现下降的趋势。通过分析低仰角水平方位扫描的雷达径向风速分布图能够解析地形对局地风场的影响,不同地形下的输电线路杆塔风速差异明显。

Typhoon Wind Field Observation Method for Overhead Transmission Lines in Coastal Area Using Doppler Lidar

To study the temporal and spatial characteristics of near-ground wind field during typhoon period and accumulate the field wind speed data around the coastal transmission line tower during typhoon,a domestic 3D scanning Doppler lidar is deployed in an in situ wind field observation campaign during the landing of No.1604 Typhoon"Nida".Data from Doppler beam swing and plain position indicator scan modes are retrieved and analyzed,verifying the capabilities of the observation method based on Doppler lidar.The results indicate that the eye zone of typhoon"Nida"shows a typical"U"shape in air pressure while its eyewall zone presents a relatively typical"double peak type"shape in wind speed.The variation of wind speed,wind direction and gust coefficient with height is obvious between the strong wind area of eyewall zone and the eye zone of typhoon.Wind speed profile above 300 m height obviously deviates from the form of exponential law or logarithmic law profile.Wind direction deflects at a certain degree to the right side under the influence of geostrophic effect from near surface to upper air,and gust coefficient decrease with the increase of height and mean wind speed.The influence of terrain on local wind field can be distinguished in radar radial wind velocity distribution map of low elevation horizontal azimuth scanning,and the wind speed around transmission towers under different terrain is obviously different.