A New Optical Method for the Determination of Atmospheric Aerosol Size Distribution

Abstract

A new optical method for the determination of the aerosol size distribution using the measurement of the solar radiation is presented. The method is as follows: The atmospheric aerosol particles are separated into finite discrete groups according to their size. Then the total spectral extinction (scattering) coefficient for solar radiation due to the atmospheric aerosol particles is expressed by the summation of each spectral extinction (scattering) coefficient due to these discrete groups of the aerosol particles. Thus the simultaneous linear equation containing the numbers of the aerosol particles in each group (the unknown quantities) which denote the total extinction (scattering) coefficients for solar radiation at various wavelength observed are obtained, then the numbers of the aerosol particles in each group, i.e. the aerosol size distribution are obtained by solving the above simultaneous equation. It is, however, troublesome to solve the above simultaneous equation one by one. So it is shown that the aerosol size distribution can be obtained by the easy and simple calculation if the inverse matrix of a matrix whose elements consist of the coefficients of the above simultaneous equation, i.e. the efficiency factors for scattering (extinction) of the aerosol particles in each group are calculated and tabulated. © 1960, Japan Meteorological Agency. All rights reserved.