Doppler lidar alerting algorithm of low-level turbulence based on velocity structure function
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摘要: 为提高激光雷达对小尺度低空湍流的预警率，提出了一种将下滑道扫描与横向速度结构函数相结合的预警算法。首先，把下滑道扫描方式下得到的扫描扇区分成多个重叠的子扇区，采用空间波动法计算每个子扇区的横向结构函数。其次，将结构函数与Von Karman模型预测的结构函数拟合得到涡流耗散率，并以国际民航组织规定的湍流阈值来判断湍流强度。使用香港天文台安装在香港国际机场实的激光雷达采集数据进行了实验验证，结果表明新方法能够检测出纵向速度结构函数未能检测出的小尺度湍流。该方法是有效的，对于提高湍流的预警率有重要意义。Abstract: To raise the alarm rate of small scale and low-level turbulence detected by lidar, an alerting algorithm based on the combination of glide-path scanning and transverse velocity structure function was presented in this paper. Firstly, the scanning sector of the glide-path was divided into several overlapping subsectors, and the transverse structure function of each subsector was calculated by using the spatial fluctuation method. Secondly, the structure function was fitted with that predicted by the theoreitical Von Karman model to give eddy dissipation rate, and the results on provisions of the International Civil Aviation Organization's turbulence threshold was compared to come to the conclusion. The performance of the proposed method was verified through the lidar collecting data of Hong Kong International Airport installed by Hong Kong Observatory. The results show that the proposed algorithm detects the small scale turbulence which longitudinal velocity structure function fails to detect. The new proposed method is effective, it is significant to raise the alarm rate.
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Key words:
- velocity structure function /
- low-level turbulence /
- lidar /
- glide-path scanning
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