偏振激光雷达在沙尘暴观测中的数据解析

阐述了日本国立环境研究所(NIES)研制的双波长偏振激光雷达的工作原理和主要工作参数，探讨了激光雷达方程在沙尘暴监测中的应用条件，并对激光雷达获取的各种信息进行直观图视化处理.分别用光学强度、后向散射强度、退偏振率、消光系数以及双波长信号比等对沙尘天气的污染特征进行了解析，并对垂直方向沙尘浓度的分布进行了计算.研究表明:退偏振率大于10%时，即可判断为沙尘天气；双波长信号比(P(1 064)/P(532))大于0.4，则表示该期间为沙尘天气；利用消光系数表示气溶胶浓度时，NIES激光雷达观测沙尘气溶胶消光系数超过0.3 km-1(ρ(TSP)约为500　μg/m3)，且持续时间超过3　h的沙尘天气现象即可判断为一次沙尘事件.根据激光雷达特有物理量对沙尘气溶胶的不同判定标准，对沙尘事件的强度、持续时间、沙尘云厚度以及沙尘天气的污染特征进行了解析和探讨. 

Application and Data Demonstration of Lidar in Sandstorm Observation

The working mechanism and main parameters of NIES (National Institute Environmental Science) dual-wavelengthpolarized lidar were expounded, the application conditions of the lidar equation in sandstorm monitoring were discussed, and visualization process of the information obtained from lidar was performed. Photo-chemical intensity, backscattered intensity, depolarization ratio, extinction coefficient and dual-wavelength rectification ratio, etc., were used to characterize the dust cloud. The distribution of dust concentration in the vertical direction was calculated. The results shows that dust events can be verified if depolarization ratio >10% or dual-wavelength signal ratio (P(1 064)/P(532))>0.4, and that dust events can also be determined by NIES lidar when dust aerosol extinction coefficient>0.3 km－1 (TSP 　massconcentration is about 500　μg/m3) and the duration time is more than3 hours. Depending on different verdict standards, the discussion on the intensity, duration, dust cloud thickness and other characters of dust events was demonstrated.