Modeling atmospheric aerosol backscatter at CO_2 laser wavelengths 2: Modeled values in the atmosphere

Abstract

Results are presented on the modeling of the aerosol backscattering function at a wavelength of 10.6 μm βCO2 in the lowest 20 km of the atmosphere. This modeling is based on direct measurements of aerosol size distributions and concentrations, as well as on optical measurements, made at visible and near-IR wavelengths. It has been found that βCO2 varies from 10−6 m−1 sr−1 in the planetary boundary layer to below 10−11 m−1 sr−1 in the stratosphere. Very low values between 10−10 and 10−12 m−1 sr−1 are also found in the remote marine-free troposphere. The probability distribution for βCO2 is discussed together with the results of converting lidar backscatter and satellite extinction measurements to the backscattering function at a 10.6-μm wavelength.