A Preliminary Assessment of the Nimbus-7 CZCS Atmospheric Correction Algorithm in a Horizontally Inhomogeneous Atmosphere

Abstract

In order to employ the Nimbus-7/CZCS to estimate the concentration of phytoplankton pigments in the oceans, it is necessary to remove the effects of the intervening atmosphere from the satellite imagery. The principal effect of the atmosphere is a loss in contrast caused by the addition of a substantial amount of radiance (path radiance) to that scattered out of the water. Although image enhancement techniques can be used to regain some of the contrast for pattern recognition purposes, the extraction of pigment concentrations requires that the radiance originating from beneath the sea surface be accurately extracted from the imagery (Gordon and Clark, 1980). A technique has been developed (Gordon, 1978) which shows considerable promise (Gordon et al, 1980) for removal of these atmospheric effects and is presently being implemented into the NASA processing system. The basic idea of this atmospheric correction algorithm is two-fold.