Solar radiation based calibration results from an ultra-portable field transfer radiometer used in vicarious calibrations

Solar radiation-based calibration (SRBC) has been used to assess radiometric calibration of earth remote sensing sensors using a source with the same spectral source that is expected during the instrument's operation. The approach has been shown capable of providing high-accuracy radiance calibration, the merits of which have been proven for laboratory and field instruments, as well as serving as a preflight calibration option for airborne and spaceborne imagers. The current work presents multiple SRBC results for a small portable transfer radiometer that was developed as part of an effort to ensure the quality of upwelling radiance at automated test sites used for vicarious calibration in the solar reflective. The results are used to develop an updated absolute uncertainty budget for the SRBC method. Comparisons of the SRBC method to standard source-based laboratory calibrations and a detector-based method recently developed for the CLARREO Pathfinder mission.