Estimation of atmospheric corrections from multiple aircraft imagery

Abstract

Remote-sensing techniques measure the radiance of the surface through a layer of atmosphere which both attenuates the signal and adds a path radiance. One class of solution can be found using the known dependence of transmittance on atmospheric path length. Multiheight measurements from aircraft enable the determination of transmittance and path radiance by linear regression. Multiangle measurements from overlapping aircraft scans have also been applied, but the difference of path lengths offered by the range of aircraft scan angles is insufficient to determine the atmospheric parameters with accuracy, especially with the uncertainties introduced by reflection from non-Lambertian surfaces. The atmosphere is not horizontally homogeneous in the presence of cloud or dense haze. Significant variations occur even at a distance from clouds and, on cloudless days, variations in optical depth can occur in dense haze layers. The variations are most significant at shorter wavelengths but have a coherent spatial distribution which can be applied to distinguish zones of different atmospheric characteristics.