A Systematic Error in Plane-Parallel Radiative Transfer Calculations

Systematic errors in plane-parallel radiative transfer calculations are examined in the context of limb radiance. Calculation of the multiple-scattering component of limb radiance using plane-parallel geometry can lead to a systematic overestimation that increases with surface albedo and tangent height. It is demonstrated that the cause of this is the overestimate of the surface-reflected radiance component. A simple yet effective correction is introduced that reduces these errors from 4%–8% to <2%. This error source may manifest itself in any application of radiative transfer calculations employing plane-parallel geometry.