基于改进的道格拉斯-普克算法确定大气激光雷达消光系数边界值  

Determination of Boundary Value of Extinction Coefficient Based on Improved Douglas-Peucker Algorithm

作　　者：费若男 孔政 宫振峰 梅亮 Fei Ruonan;Kong Zheng;Gong Zhenfeng;Mei Liang(School of Optoelectronic Engineering and Instrumentation Science,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学光电工程与仪器科学学院,辽宁大连116024

出　　处：《中国激光》2023年第14期194-206,共13页Chinese Journal of Lasers

基　　金：国家自然科学基金(62075025);大连市高层次人才创新支持计划(2020RQ018);中央高校基本科研业务费(DUT22JC17)。

摘　　要：大气激光雷达已广泛应用于大气污染源水平扫描测量,而水平扫描测量激光雷达信号的消光系数边界值求解及廓线反演是其定量化应用的关键。针对这一问题,提出了一种基于改进的道格拉斯-普克(DP)算法确定消光系数边界值的新方法,并结合经典Klett方法实现水平扫描测量时的大气消光系数稳健反演。系统性地研究了经典DP算法在消光系数边界值求解时的性能及潜在的问题。在此基础上,提出将对数激光雷达信号与对应直线线段的偏离方差作为阈值控制手段,以替代经典DP算法中的最远距离阈值,从而更加准确地获取对数激光雷达曲线的线性区间,进而利用斜率法求解消光系数边界值。通过消光系数反演结果的对比分析,验证了改进DP算法的有效性。利用该方法反演的消光系数与周围空气污染监测站的PM10颗粒物浓度具有较高的相关性(>0.88)。研究结果表明,提出的改进DP算法可为水平扫描激光雷达信号的消光系数边界值求解和廓线反演提供有效的方法。Objective Atmospheric lidar has been widely used in horizontal scanning measurements for air pollution monitoring in recent years.The determination of the boundary value of the aerosol extinction coefficient(AEC) and the retrieval of the AEC profile are the key issues for quantitative atmospheric applications.In this work,a new method based on an improved Douglas-Peucker(DP) algorithm is proposed to find the linear region in the logarithmic lidar curve,from which the boundary value of the AEC is estimated.Combined with the classical Klett method,the AEC profile can be obtained in horizontal scanning measurements.The feasibility and performance of the improved DP algorithm has been validated through comparison studies of the AEC scanning map.Methods The experimental data evaluated in this work were obtained by a scanning Scheimpflug lidar(SLidar) system installed in Xianyang City,Shaanxi Province(Fig.1),employing high power laser diodes as light sources and area image sensors as detectors.The elevation angle of the SLidar system during horizontal scanning measurements is about 3°.The scanning period is about 20 min with a rotation step of 2°.The DP algorithm has been proposed to automatically search linear regions in the logarithmic lidar signal.The DP algorithm decimates the original logarithmic lidar curve to a similar curve with fewer points through an iterative end-point fit algorithm.Besides,the variance of the distance between the logarithmic lidar signal and the corresponding line segment is used as the threshold to replace the farthest/maximum distance threshold in the classical DP algorithm,which can be used to obtain the linear region of the logarithmic lidar curve more accurately.The slope method is then employed for the determination of the AEC boundary value in the linear region,where the atmosphere is considered to be homogeneous.With the boundary value of the AEC as the input,the AEC profile can be obtained in horizontal scanning measurements according to the Klett method.Long enough linear region

关 键 词：大气光学 沙氏激光雷达 道格拉斯-普克算法 边界值 消光系数 大气污染 

分 类 号：TN958.98[电子电信—信号与信息处理]