Lunar calibration of the GMS-5 visible band

Calibration of the visible band of the VISSR radiometer on the Geostationary Meteorological Satellite GMS-5 is necessary for quantitative analysis of the images it produces. Applications include the retrieval of quantities such as aerosol amount, surface albedo and cloud properties. The lunar photometry program conducted by the US Geological Survey with its Robotic Lunar Observatory (ROLO) is establishing the Moon as a radiometric calibration target for space-based Earth observation sensors. The occasional appearance of the Moon in the operational GMS-5 images near the times of ROLO observations has allowed the acquisition of several pairs of images with almost identical view and illumination geometry at ROLO and GMS-5. The lunar disk presents a range of radiances and has a diameter of a few hundred pixels in both the ROLO and GMS-5 images. This allows, from a single image pair, calibration over most of the GMS-5 dynamic range used by clear terrestrial land scenes. An absolute calibration of the GMS-5 sensor to within several percent has been derived from one of the ROLO-GMS image pairs. The advantages of lunar calibration over other calibration methods are discussed