蒙特卡罗方法模拟水云对偏振激光雷达的多次散射去极化

Monte Carlo Simulation of Polarization Lidar Multiple Scattering Depolarization by Water Cloud

利用激光雷达探测水云的光学和微物理特性时,水云的多次散射会在雷达回波中产生去极化信号,给出了半解析蒙特卡罗方法模拟偏振激光雷达后向散射去极化率的详细过程,给出了0.532μm激光作为光源入射时,典型水云的后向散射Muller矩阵二维分布图,以及水平线偏振、垂直线偏振、+45°线偏振和右旋圆偏振光入射时,后向散射的Stokes矢量的二维分布图,最后给出了去极化率和极化率随激光雷达接收视场角以及穿透深度的变化。从数据结果可以看出,接收视场角越大,多次散射的影响越大。给出的蒙特卡罗模拟方法对利用激光雷达遥感反演水云和球形气溶胶的特性具有重要的应用价值。

The polarization lidar returns exist a depolarization signal in liquid water clouds due to the occurrence of multiple scattering when the optical and microphysical characteristics of liquid water clouds are detected by lidar. The detailed process of semi-analytic Monte Carlo simulation is given to study the backscattering depolarization of polarization lidar. The backscattering Muller matrix 2D images are given for the liquid water clouds with the laser at 0.532 μm as the light source. The 2D images of backscattering Stokes parameters are given for the horizontal linear polarization, vertical linear polarization, ＋45° linear polarization and right circular polarization states of light incidence. The depolarization and the polarization ratios are given for different lidar receiver field of view angles and depth from the cloud base. From the results, it can be seen that the impact of multiple scattering increases with the increase of receiver field of view angle. The proposed Monte Carlo simulation method has great value for remote sensing of water clouds and spherical aerosol characteristics.