The use of scattering theory to infer atmospheric optical parameters requires the separation of absorption and scattering. It is demonstrated that a gradient flux relation exists that would provide the absorption (altitude) profile independently of scattering and irrespective of the state of polarization of the light field. The relation is derived for an atmosphere of plane-parallel or spherical geometry and for broad (continuum) and narrow (spectral line) frequency bands. The results are shown to hold, in particular, for the polarizations induced by both Rayleigh and Mie scattering in the field. Experimental setups are proposed for each of the cases considered of atmospheric geometry and frequency bandwidth. A final discussion considers the relevance of the present determination of the atmospheric absorption profile to the related problems of aerosol relative concentration, interpretation of radiometric and spectrometric data formed in the presence of scattering, clouds morphology, and radiative heat budget of the atmosphere.
A. L. Fymat and J. Lenoble, "Absorption Profile of a Planetary Atmosphere: A Proposal for a Scattering Independent Determination," Appl. Opt. 11, 2249-2254 (1972)