摘要:
非球形气溶胶是影响辐射传输的重要因素。系统给出了矢量辐射传输Monte Carlo模型,并验证了其准确度;考虑入射光偏振态,讨论了不同方向漫射光Stokes矢量对气溶胶形状的敏感性;分析了气溶胶形状、入射光偏振状态对光波退偏振度、透过率及反射率的影响。模拟仿真结果表明,对于不同偏振态的入射光,不同方向的Stokes矢量对气溶胶形状变化的灵敏程度并不一致,而在天顶角0?方向区域, Q, U及V 分量对形状的灵敏程度普遍不高;气溶胶形状对反射漫射光退偏程度的影响强于透射漫射光,入射光偏振态不同,漫射光退偏程度也存在较大差异。气溶胶形状对光波整体透过率与反射率影响显著,且该影响随传播距离增大而增大;入射光偏振态对透过率与反射率影响相对较小,与自然光相比,水平偏振光透过率略偏小,反射率略偏大,垂直偏振光反之,圆偏振光与自然光的模拟结果相当。
Abstract:
The shape of atmospheric aerosol is an important factor that influences radiation transfer. In this paper, a vector radiation transfer model based on Monte Carlo method is systematically introduced, and its accuracy is validated against the published results. And the sensitivity of Stokes vectors of transmitted and reflected light to aerosol shape is discussed when polarized light incidents. In addition, the influence of the particle shape on the depolarization ratio, transmission rate and the reflection rate is analyzed for incident light with different polarization states. Simulation results show that for the incident light in different polarization states, the sensitivity of the Stokes vectors of the diffuse light to different aerosol shapes is not the same in different viewing directions, and the Q, U , V elements of Stokes vector are all insensitive to the change of particle shape near the direction of the zenith angle 0?. It is evident that the aerosol shapes have a stronger influence on the depolarization ratio for reflected diffuse light compared with that for transmitted diffuse light, and there are also remarkable differences between the degree of depolarization of the diffuse light when the polarization states of the incident light are different. Results also show that the aerosol shape has a significant influence on the whole transmission rate and the reflection rate, and with the increasing of propagation distance, the influence also becomes more remarkable. Compared with particle shape, the influence of polarization states of incident light is relatively small, the transmission rate of horizontally-polarized light is slightly larger than that of unpolarized light, while for perpendicularly-polarized light, its results is opposite. For circularly polarized light, the results is almost the same as that of unpolarized light.