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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。
In order to improve the pre-warning rate of laser radar on small-scale low-altitude turbulence, a pre-warning algorithm combining glide slope scanning and lateral velocity structure function is proposed. First, the scan sector obtained by the glide-slope scanning method is divided into a plurality of overlapping sub-sectors, and the spatial structure function of each sub-sector is calculated by using the spatial fluctuation method. Secondly, the structure function is fitted with the structural function predicted by the Von Karman model to obtain the eddy current dissipation rate, and the turbulence intensity is determined by the ICAO turbulence threshold. Experimental results using lidar data collected by the Hong Kong Observatory at the Hong Kong International Airport show that the new method can detect small-scale turbulences not detected by the longitudinal velocity structure function. This method is effective and has important significance for improving the early warning rate of turbulence.