Comparing Hyperion Lunar Observation with model calculations in support of GOES-R Advanced Baseline Imager (ABI) calibration

Abstract

Radiometric stability of the lunar surface and its smooth reflectance spectrum makes the moon an attractive candidate for calibrating satellite-based hyper/multi-band visible and infrared imagers. Long-term performance monitoring of satellite instrument using Moon can reveal the degradation of instruments. In this paper, analysis of Hyperion lunar observations and comparison with lunar model are performed in support of Cal/Val activities for satellite photometric imager such as GOES-R Advanced Baseline Imager (ABI) instrument. Hyperion makes hyper-spectral observations of the moon regularly with moon phase mostly at 7 degree and it covers visible and shirt-wavelength infrared (SWIR) channels with 10 nm spectral resolution. Five Hyperion lunar observations are analyzed. Lunar reflectance is derived from Hyperion observation and the mean absolute lunar spectral reflectance difference between Hyperion derivation and lunar model is 4.0 ± 2.62%. Through reflectance comparison, over-compensation of two strong atmospheric water absorption bands in Hyperion calibration is identified. The radiometric variance and degradation of Hyperion are assessed. To support the calibration of GOES-R ABI, hyper-spectral data of Hyperion lunar observation is convoluted with ABI spectral response functions for reflective solar bands to synthesize predicted lunar images to be observed by ABI. Lunar irradiances are derived from these synthesized lunar images for ABI and compared with lunar model predictions to quantify spectral biases. Long-term lunar imaging window of opportunities for GOES-R ABI are also assessed. The ability of using lunar model and Hyperion observation to calibrate satellite VNIR/SWIR sensors and reduce the measurement uncertainties is essential to support post-launch Cal/Val activities of GOES-R ABI.