Atmospheric Correction

Abstract

There is little doubt that the atmospheric correction algorithm described by Eq. 13 in Section II-B is applicable over some portion of a CZCS scene when S(λ,λ_o) can be found, and when L_w(λ_o) = 0. Initially, it was envisioned that S(λ,λ_o) could be determined from surface measurements of the aerosol optical depth τ_A, using Eq. 12 in conjunction with the assumption that ω_A and P_A are independent of wavelength. Alternatively, measurements of L_w (actually L_u) could be used directly with Eq. 13 to provide S(λ,λ_o). Since it is unlikely that S(λ,λ_o) would be determined at many locations in an image, one is actually forced to assume that S(λ,λ_o) remains essentially constant even though the turbidity of the atmosphere may vary considerably from location to location. Gordon (1981a) has shown that S(λ,λ_o) can in fact remain nearly constant in a horizontally inhomogeneous atmosphere. As mentioned above, a sufficient condition for this is that the aerosol size distribution (normalized to the total concentration) and refractive index be independent of position over the image even in the presence of variations in the total concentration.