研究大气中变形球状的气象粒子对电磁波以及激光的散射特性,采用广义米氏(Mie)理论,精确地求解在任意波束中大气粒子的散射强度,数值计算激光束腰位置对散射强度分布的影响,分析彩虹强度和散射角与变形球状粒子偏心率的关系,研究随着长短轴比例增加,彩虹强度峰值的偏移。计算结果表明雨滴在下降过程中,它在各个方向的光散射强度逐步减弱,即随着雨滴偏心率的增大,散射强度减少,彩虹角变大。对于激光入射,当粒子距离波束中心位置越远,粒子的散射就越弱,并且随尺寸参量增加,后向散射振荡的频率要大于前向散射,当束腰位置矢径的大小增加时,后向散射和前向散射强度均变小。

The electromagnetic scattering properties of spheroidal aerosols are investigated. The numerical values of the scattering intensity under arbitrary shaped beam illumination of aerosols are evaluated by using a generalized Lorenz-Mie theory. The distribution of the scattering intensity is given as the function of the position of the laser beam waist. The dependence of rainbow intensity and scattering angle on ellipticity of the spheroidal aerosols is analyzed and a shift of the main peak with the increase of ratio a/b is observed. The calculation shows that in the falling process of the raindrop, the scattering intensity of all directions decreases gradually, in other words, the scattering intensity decreases and the rainbow angle expands with the rise of ellipticity of the raindrop. In the case of laser incidence, the farther of the aerosol is from the laser beam center, the weaker the scattering intensity is. With the scale parameter increasing, the oscillating frequency of the back scattering is larger than that of the forward scattering, and both of them decrease with the increase of the radius vector magnitude of the laser beam waist.