基于时域有限差分法的非球型气溶胶和卷云粒子散射特性研究

Research on Scattering Properties of Non-Spherical Aerosols and Cirrus Particles Based on the Finite Difference Time Domain Method

本文选取3种气溶胶粒子和3种卷云粒子,利用时域有限差分法,对椭球型气溶胶粒子和六棱柱卷云粒子在不同波长下散射相位函数进行了仿真分析,并讨论了入射方向对粒子散射特性的影响。仿真结果表明,尺寸参数较小时散射相位函数变化较平稳,尺寸参数较大时曲线出现震荡,且随尺寸参数增大震荡剧烈;粒子单次散射能量主要集中在前向散射,随散射角增大呈指数下降;气溶胶粒子散射相位函数在90-150°之间出现明显的波谷;卷云粒子散射相位函数一般不出现明显波谷。当入射角度改变时,气溶胶粒子在整个0-180°之内的散射相位函数都有101数量级的变化,卷云粒子则在0-90°前向散射内保持稳定。本文的研究方法和结论可以为研究天空偏振光模式的形成机理和变化规律提供参考。

The scattering phase function were simulated and analyzed in terms of wavelengths by using ellipsoid aerosols and hexagon cirrus particles, and the influence of different incidence on scattering properties were discussed by the Finite Difference Time Domain method. The simulation results show that when the size parameter is relatively small, the scattering phase function curve is quite smooth,the curve shocked heavier as the size parameter becoming larger. The scattering energy mainly distributes in the forward direction, it decreased exponentially as the scattering angle increases. For aerosols, the scattering phase function has a minimum value ranging from 90 to 150 degrees but for cirrus doesn＇t. The scattering phase function significantly varies for aerosols （nearly in steps of 101 ） when changing the incident direction. While for cirrus, we can only see the difference when the scattering energy distrib- utes in the backward direction. It is quite stable for the scattering angle ranging from 0 to 90 degrees. The methods and conclusions can provide references of the formation and variation of polarized light pattern.