Retrieval of aerosol size distribution from angular scattering functions: effects of particle composition and shape

The retrieval sensitivity in regard to the recovery of aerosol size distributions using particle angular scattering properties is investigated. Previous retrieval methods have all assumed that the scattering characteristics of spheres is adequate to retrieve size distributions. The present results show that particle nonsphericity can have a significant effect upon the retrieval. In particular assumptions based upon Mie spheres may lead to interpretations of spurious multimodal distributions. Furthermore, it is also shown that shape effects cannot be separated from composition effects. The effect on retrieved size distributions is investigated due to (1) variations in the particle index of refraction, (2) truncation of angular scattering intensities due to measurement limitations, (3) the use of two-component shell particles, (4) nonsphericity using the semi-empirical approach, and (5) the replacement of spherically shaped particles by cylindrically shaped fibers.