Modeling atmospheric aerosol backscatter at CO_2 laser wavelengths 1: Aerosol properties, modeling techniques, and associated problems

Abstract

This paper presents the results of investigations into the problems associated with modeling the atmospheric aerosol backscattering function βCO₂ at CO₂ laser wavelengths in the lowest 20 km of the atmosphere. It contains a summary of the relevant aerosol characteristics and their variability together with a discussion of the measurement techniques and the errors involved. The different methods of calculating βCO₂ both from measured aerosol characteristics and from optical measurements made at other wavelengths are discussed in detail, and limits are placed on the accuracy of these methods. The most significant factor in determining βCO₂ has been found to be the aerosol size distribution and concentration, which should be known accurately for particle radii up to at least 1 μm for stratospheric particles and 5 μm for tropospheric particles.