Opt Express. 2023 Mar 13;31(6):10541-10553. doi: 10.1364/OE.484335.
Polarization measurements have been widely used to detect aerosol properties by remote sensing in recent decades. To better understand the polarization characteristics of aerosols by lidar, the numerically exact T-matrix method was used to simulate the depolarization ratio (DR) of dust and smoke aerosols at typical laser wavelengths in this study. The results show that the DRs of dust and smoke aerosols have obviously different spectral dependences. Moreover, the ratio of DRs at two wavelengths has an obvious linear relationship with the microphysical properties of aerosols, including aspect ratio, effective radius and complex refractive index. At short wavelengths, we can use it to invert the absorption characteristics of particles, further improving the detection ability of lidar. Comparing the simulation results of different channels, DR, (color ratio) CR and (lidar ratio) LR have a good logarithmic fitting relationship at 532 nm and 1064 nm, which helps to classify the aerosol types. On this basis, a new inversion algorithm, "1β+1α+2δ", was presented. By this algorithm, the backscattering coefficient (β), extinction coefficient (α), DR (δ) at 532 nm and 1064 nm can be used to expand the range of inversion and compare lidar data with different configurations to obtain more extensive optical characteristics of aerosols. Our study enhances the application of laser remote sensing in aerosol observations more accurately.
偏振测量在最近几十年中已被广泛用于通过遥感探测气溶胶特性。为了更好地理解激光雷达对气溶胶的偏振特性，本研究采用数值精确的 T 矩阵方法模拟了典型激光波长下灰尘和烟雾气溶胶的退偏比 (DR)。结果表明，灰尘和烟雾气溶胶的 DR 具有明显不同的光谱依赖性。此外，两个波长处的 DR 比值与气溶胶的微物理特性（包括纵横比、有效半径和复折射率）之间存在明显的线性关系。在短波长下，我们可以用它来反演粒子的吸收特性，进一步提高激光雷达的探测能力。通过比较不同通道的模拟结果，在 532nm 和 1064nm 处，DR、（颜色比）CR 和（激光雷达比）LR 具有良好的对数拟合关系，有助于对气溶胶类型进行分类。在此基础上，提出了一种新的反演算法“1β+1α+2δ”。通过该算法，可以使用 532nm 和 1064nm 处的后向散射系数 (β)、消光系数 (α)、DR (δ) 扩展反演范围，并比较不同配置的激光雷达数据，从而获得更广泛的气溶胶光学特性。我们的研究更准确地增强了激光遥感在气溶胶观测中的应用。
