Comparison of SAGE II solar extinction data with airborne measurements of atmospheric backscattering in the troposphere and lower stratosphere

Abstract

Since October 1984 the SAGE II limb sounding satellite has been measuring the extinction σ(λ) of the Earth's atmosphere in seven wavebands. The extinction at the longest wavelength, σ (1.02 μm), is largely due to participate material (aerosols) in the atmosphere. It is of considerable interest to relate these extinction values to the strength of atmospheric backscattering at this and longer wavelengths. In particular, atmospheric backscattering coefficients β (π, λ) in the 9–11 μm range are important because projected performance of a satellite-borne CO₂ lidar for global wind measurement depends critically on their magnitude (the π signifies backscatter). In April 1986, during passage of the SAGE II satellite, the first simultaneous measurements of β (π, 10.6 μm) were made with an airborne CO₂ lidar. Individual ratios of β (π, 10.6 μm) and SAGE II extinction σ (1.02 μm) are in reasonable accord with previously calculated values, but the trend with height shows a distinctly nonlinear relation , which is probably attributable to a steadily changing size distribution of aerosols.