论文部分内容阅读
激光雷达探测水云时,多次散射会使雷达回波产生退偏振效应,云层对激光的退偏振比与云层微物理特性信息含有特定的关系,利用这种关系可以反演云层的微物理特性,但是这种关系需要利用理论模拟进行研究和探索,理论模拟激光雷达退偏振效应的方法主要是蒙特卡罗方法。给出了两种不同思路的蒙特卡罗模拟方法:一是通过跟踪光子在每一次散射后,由光子方向矢量和Z轴构成的子午面来模拟,光子相对于子午面的偏振状态由斯托克斯参量表示;二是将光子的偏振状态用一个三元单位矢量组来表示,每次散射后,根据统计抽样得到的散射角和方位角对其进行旋转,从而跟踪光子偏振态的变化。给出了详细的模拟过程,并利用两种方法分别计算了水云的退偏振比,模拟结果显示这两种方法得出的结果完全一致。
When laser radar detects water clouds, multiple scattering can depolarize radar echoes, and the depolarization ratio of clouds to laser and cloud microphysical properties information have a specific relationship. By using this relationship, it is possible to retrieve the microphysical characteristics of clouds However, this relationship needs to be studied and explored by using theoretical simulation. The method of theoretically simulating the depolarization effect of laser radar is mainly the Monte Carlo method. Two different methods of Monte-Carlo simulation are given: one is to simulate the meridian plane formed by the photon direction vector and the Z-axis after each scattering of the photons. The polarization state of the photons with respect to the meridional plane is simulated by Stowe The second is that the state of the photon’s polarization is represented by a vector of ternary units. After each scattering, the states of the photons are tracked according to the scattering angle and azimuth angle obtained by statistical sampling. The detailed simulation process is given and the depolarization ratio of water cloud is calculated respectively by two methods. The simulation results show that the results obtained by the two methods are completely consistent.