On the aerosol backscattering coefficient in atmosphere in the spectral range 9 – 13.5μm

The aerosol backscattering coefficient β_π in a surface atmospheric layer is calculated at the emission lines of NH₃ and CO₂ lasers (9 – 13.5 μm). It is shown that the coefficients β_π at the emission lines of an NH₃ laser (11 – 13.5 μm) are comparable with the coefficients β_π at the emission lines of a CO₂ laser near 10.6 μm. The dependence of β_π on the humidity and type of aerosols is studied. It is also shown that the coefficient β_π in a surface atmospheric layer at the lasing of an NH₃ laser varies from 10^-10 to 7×10^-9 cm^-1 sr^-1. The lidar aerosol ratio is calculated as a function of the mean aerosol radius. It is found that this ratio is independent of the particle size for aerosol particles of radius exceeding 40 μm for the 11.7-μm aP(4,0) line of the ammonia laser.