非球形气溶胶前向散射对消光的影响

Influence of Nonspherical Aerosols’ Forward-Scattering on Light Extinction

非球形气溶胶的前向散射导致太阳辐射计测量消光系数的结果有误差,需要进行前向散射修正。采用T矩阵法,研究了椭球形、圆柱形和切比雪夫形粒子的前向散射特性以及对前向散射修正因子的影响。研究表明,椭球粒子的前向散射强度随着等效半径和轴比的增大而增大。沙尘气溶胶粒子中,修正因子会随粒子尺寸参数的增大呈现一个振荡减小的趋势,尺寸参数超过10后,前向散射修正因子将低于0.98,随尺寸参数的增大,修正因子达到0.96左右,不同轴比的椭球粒子和不同长度直径比的圆柱形粒子对修正因子影响较大,切比雪夫粒子的形变参数和波纹参数对修正因子没有明显的影响。研究结果可为大气气溶胶粒子的前向散射研究以及太阳辐射计等相关应用提供理论指导。

The forward scattering of nonspherical aerosols leads to errors in the extinction coefficient measured by the solar radiometer, the error needs to be corrected theoretically. The forward scattering characteristics of ellipsoidal, cylindrical and Chebyshev particles and their effects on the forward scattering correction factor are studied by T-matrix method. The results show that the forward scattering intensity of ellipsoidal particles increases with the increase of equivalent radius and axial ratio. In dust aerosol particles, the correction factor will oscillate and decrease with the increase of particle size parameters. When the size parameters exceed 10, the forward scattering correction factor will be lower than 0.98. With the increase of the parameters, the correction factor will reach about 0.96. Ellipsoidal particles with different axial ratios and cylindrical particles with different length diameter ratios have great influence on the correction factor, while the deformation parameters and ripple parameters of Chebyshev particles have no obvious influence on the correction factor. These results provide theoretical guidance for studying forward scattering of atmospheric aerosol particles and the application of solar radiometer.