为分析形状对气溶胶粒子散射特性的影响,采用T矩阵法计算了0.633 μm波段(自然光)不同种类、形状的气溶胶单粒子与体散射的散射相函数,并讨论了气溶胶粒子形状畸变与等效Mie散射误差的变化规律.结果表明:粒子形状畸变对气溶胶粒子散射能量空间分布影响较大.对于单粒子,各散射角上的等效Mie散射误差并不随粒子形状畸变程度单调变化.从相对误差量级上看,形状畸变对180°散射的影响强于0°,对35°的散射影响相对较弱.对于两种非球形粒子等效方法,等表面积法优于等体积法.不同类型的非球形气溶胶粒子体散射存在显著差异,沙尘性与海洋性的等效Mie散射误差明显大于煤烟性与可溶性粒子;对于同一种气溶胶,形状的改变对侧向与后向散射影响显著,对前向散射影响不大.
To analyze the influence of shape deformation on the scattering property of atmospherical aerosols,T-Martrix method is used to calculate the scattering phase functions of particles with different types and shapes at a wavelength of 633 nm (unpolarized light).In addition,the variation law between shape deformation and equivalent Mie scattering error is also discussed in this paper.Result shows that the shape deformation has great effects on the space distribution of seattering energy; the relationship between equivalent Mie scattering error and shape deformation is more complex than that ever has assumed.The dynamic range of equivalent Mie scattering error found that shape deformation influences the scattering phase functions more at 0° than at 180°,while at 35°,the effect is small; for the sphere-equivalent methods,surface-area equivalent method is more applicable in calculating the scattering characteristics of non-spherical particles.A great discrepancy exists in volume scattering phase functions of aerosols with different physical characteristics.Equivalent Mie scattering errors of sand and maritime aerosols are bigger than those of smoke and dissolvable aerosols.For the volume scattering of particles of the same kind,shape deformation has significant influence on side and backforward scattering,but has little on the forward scattering.