Retrieval of stratospheric aerosol size distribution from atmospheric extinction of solar radiation at two wavelengths

Abstract

The possibility of retrieving size distribution of aerosol particles in the stratosphere by measuring the extinction of solar radiation traversing the aerosol medium at two different wavelengths is explored in this work. This paper presents a parametric study of the effects of size distribution and composition of stratospheric on the value R, the ratio of extinction of solar radiation at wavelength 0.45 μm to the extinction at aerosols wavelength 1.0 μm. The aerosol size distributions under study are nine analytical expressions including most stratospheric aerosol models used by investigators. The aerosol compositions under study are the supercooled sulfuric-acid droplets, with different weight percentages of H2SO4 in the aerosol. It is found that R is not very sensitive to either the composition or the radii limits of stratospheric aerosols under consideration but is quite sensitive to the value of the variable parameter governing the mode radius of the size distribution of aerosol particles. Based on the results of this parametric study, a method of retrieving the size distribution of aerosol particles in the stratosphere from the experimental results of the extinction of solar radiation at two wavelengths is proposed.