Modeling atmospheric aerosol backscatter at CO_2 laser wavelengths 3: Effects of changes in wavelength and ambient conditions

Abstract

The effects of changes in wavelength and ambient conditions on the atmospheric backscatter at CO2 wavelengths have been examined. It has been found that, with the exception of (NH4)2SO4-containing aerosols, whose size distributions have relatively large numbers of small particles, the variation of backscatter with CO2 wavelength is less than a factor of ~3. However, for such (NH4)2SO4 aerosol distributions, the variation of backscatter function with CO2 wavelengths between 9.1 and 11.1 μm may reach 1 order of magnitude. The effects of ambient humidity and temperature changes are negligibly small when the relative humidity is low (<75%). However, for a humid environment (>90%), a few percent change in humidity or a few degrees change in temperature may cause noticeable change in backscatter from aerosol particles of small sizes.