Unified approach to absolute radiometric calibration in the solar-reflective range

The need is identified for a unified approach to the preflight and in-fligh t absolute radiometric calibration of satellite sensors, which does not dep end on the accurate transfer of lamp and detector calibrations from the lab oratory to orbit. Such an approach is described that uses the sun to provid e the link between preflight solar radiation-based calibration (SRBC), in-f light solar diffuser-based calibration, and vicarious calibration. Examples are given of these methods and uncertainty estimates are provided. It is s hown that an uncertainty with respect to solar exoatmospheric irradiance, o f <3%, 1 sigma, can be attained for each method and that each can, if neede d, be accurately related to national laboratory standards. In addition to p roviding the link between preflight and in-flight on-board calibrations, th is unified approach also fills the critical need to relate these calibratio ns to those of the radiometers used for vicarious calibration and data-prod uct, field-validation measurements, by also referencing them to the same so lar-irradiance scale. (C) 2001 Elsevier Science Inc. All rights reserved.