移动式多普勒激光雷达光束扫描及风场反演技术研究

Beam Scanning and Wind Inversion Technique of a Mobile Doppler Lidar

移动式多普勒激光雷达在外场实验过程中,考虑到工作平台的随机性,测量坐标系很可能不再是地面参考坐标系,这为三维矢量风场的反演带来困难。提出采用三维空间坐标旋转变换的方法建立了测量坐标系与地面参考坐标系的一般关系式,并进一步导出了反演三维风场的普遍公式。此外,在光束扫描过程中,由于二维扫描仪加工精度等的限制,光束存在一定的定向误差。采用Monte-Carlo模拟方法定量研究了光束指向偏差引起的风场测量误差,结果表明,当水平风速为100m/s时,1°的光束定向误差引起的水平风速大小误差为0.712m/s,方向误差为0.704°,与理论计算结果一致。理论分析结果还表明:当水平风速为100m/s时,1°的光束最大定向偏差引起的水平风速大小的最大偏差为1.16m/s,方向最大偏差为1°。

During the field campaign, after taking into account the randomness of the working platform, the measuring coordinate system of the mobile Doppler lidar may no longer be the ground reference frame, which will lead to difficulty for the three-dimensional vector wind field inversion. Three-dimensional space coordinate rotation transformation method is proposed to establish the general relation between the measurement coordinate system and the ground reference frame, and then a general formula for three-dimensional wind field inversion is derived. In addition, in the process of beam scanning, due to the restriction of two-dimensional scanner machining precision and other limitations, there is a certain orientation error of the laser beam. The wind field measurement errors caused by beam pointing deviation are studied quantitatively by using Monte-Carlo simulation method. The results show that when the horizontal wind speed is 100 m/s, the horizontal wind speed error is 0. 712 m/s and wind direction error is 0. 704° for 1° beam orientation error, which is consistent with the theoretical results. The results of theoretical analysis also show that when the horizontal wind speed is 100 m/s, the maximum deviations of horizontal wind speed and direction would be 1.16 m/s and 1° respectively for 1° maximum deviation of beam direction.