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扫描激光雷达可以获取大气剖面,对于了解边界层与云的结构、污染物分布与输送有重要的作用。斜程扫描下,天顶角较大时传统Fernald和Klett消光系数反演方法不再适用,可采用经典两角度方法对激光雷达常数进行校正,进而获取大气消光系数。但经典两角度法求解雷达常数时存在多解问题,如何设定约束条件求取最优解是较难解决的问题。从经典两角度方法出发,在两条斜程上筛选出的大气缓变区域,假定水平均匀,通过线性回归的方法估算雷达常数,并采用一系列约束条件以求取雷达常数最优解,最终得到斜程扫描下消光系数分布,较好地解决了两角度测量中多解问题求解的困难。通过实验验证,即使在天顶角较大或者信号质量不是很好的情况下,消光系数反演依然能够获得较好的效果。结果表明,该方法能够很好地反映出大气的空间结构。
Scanning Lidar can obtain the atmospheric profile, which plays an important role in understanding the structure of boundary layer and cloud, the distribution and transport of pollutants. The traditional Fernald and Klett extinction coefficient inversion method is no longer suitable for the large zenith angle under the oblique scan. The classical two-angle method can be used to calibrate the Lidar constant, and then obtain the atmospheric extinction coefficient. However, the classical two-angle method solves the radar constants, there are many problems, how to set the constraint to obtain the optimal solution is more difficult to solve the problem. Starting from the classical two-point method, the atmospheric slow-change areas screened on two slopes are assumed to be horizontal and the radar constants are estimated by linear regression. A series of constraints are used to obtain the optimal solution of the radar constant. Finally, Obtained the distribution of the extinction coefficient under the ramp scanning, and solved the difficulty of solving the multi-solution problem in the two-angle measurement. Experimental results show that the extinction coefficient inversion can still achieve good results even with large zenith angle or poor signal quality. The results show that this method can well reflect the spatial structure of the atmosphere.