Under a general approximation of multiple scattering paths involving small-angle scatterings interspersed with occasional large-angle scatterings, we performed Monte Carlo vector radiative transfer simulations to investigate the spatial and temporal distribution of the reduced Mueller matrix (RMM) of lidar returns from water clouds. Our findings indicate that the normalized RMM elements M̃22′ and M̃33′ are highly affected by two types of scattering plane randomizations: the overall rotation of scattering planes along multiple scattering paths, and the correlation of the rotation of scattering planes along sub-paths separated by large-angle scatterings. The simulation results reveal that the specific geometries of lidar multiple scattering paths, driven by strong forward-scattering in water clouds, result in the two scattering plane randomizations producing markedly different effects on the linear polarization. This insight not only elucidates the varying decline rates in linearly cross-polarized pattern contrast and linear polarization degree observed in current on-beam lidars but also establishes a basis for analyzing polarized signals in potential future off-beam lidar systems.

中文翻译：

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散射平面随机化对来自水云的激光雷达多散射偏振信号的影响


在涉及小角散射和偶尔的大角散射的多散射路径的一般近似下，我们进行了蒙特卡洛矢量辐射传输模拟，以研究水云激光雷达回波的简化穆勒矩阵 （RMM） 的空间和时间分布。我们的研究结果表明，归一化的 RMM 元素 M̃22' 和 M̃33' 受两种类型的散射平面随机化的高度影响：散射平面沿多个散射路径的整体旋转，以及散射平面沿由大角度散射分隔的子路径旋转的相关性。仿真结果表明，由水云中的强前向散射驱动的激光雷达多散射路径的特定几何形状导致两个散射平面随机化对线性极化产生明显不同的影响。这一见解不仅阐明了当前对射激光雷达中观察到的线叉极化图案对比度和线性偏振程度的不同下降率，而且为分析未来潜在的离束激光雷达系统中的偏振信号奠定了基础。