Application of Mie scattering to radiative transfer in an aerosol-laden atmosphere

Abstract

The numerical solutions of Mie scattering theory are adapted for computations of normalised single scattering phase functions and related scattering parameters for optically thin mono- and polydisperse atmospheric aerosols, including clouds and hazes. For the polydisperse case, an investigation into the accuracy and savings in computer processing time is made for Gauss-Laguerre integration over particle size parameter, relative to the more commonly used trapezoidal integration. The single scattering phase functions are in turn used as input to a doubling routine which accounts for multiple scattering in an optically thick plane-parallel atmosphere. The doubling routine is a numerical method based on the radiative doubling equations given by J.E. Hansen (1970). The angular distribution of the diffuse transmitted and reflected intensities of radiation may be calculated for aerosols of given size distribution, complex refractive index and optical depth. Any wavelength and direction of incident radiation may be considered.