Calibration Against the Moon. I: A Disk-Resolved Lunar Model for Absolute Reflectance Calibration
ATMOSPHERIC AND ENVIRONMENTAL RESEARCH INC LEXINGTON MA
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We present a model of the absolute radiance of the disk-resolved Moon at visible to near infrared wavelengths. It has been developed in order to use the Moon as a calibration reference, particularly by space-based sensors observing the Earth. We begin with the development of Hillier et al. Hillier, J., Buratti, B., Hill, K.1999. Icarus 141, 205-225 for the reflectance as a function of phase angle and base the lunar reflectance on the Clementine 0.750 mum basemap. We adopt Hapkes Hapke, B. 2002, Icarus 157. 523-534 expression for the multiple scattering term, including the more accurate approximation to the Chandrasekhar H function. The geometry is based on the Jet Propulsion Laboratory Lunar Ephemeris DE421, and the topographic slope is from the Kaguya-LALT laser altimetry Araki, II., and 10 colleagues 2009. Science 323, 897-900. We define three types of terrain by combining the reflectance from the Clementine basemap and the topographic model to specify maria, highlands, and crater regions, and allow mixed types between each class. Parameters of the model are solved for as a function of surface type and wavelength by comparison against data chips from the Robotic Lunar Observatory ROLO Kieffer, II. II.. Stone. T. C. 2005. Astron J. 129, 2887-2901. The reflectance in any waveband maybe computed by spectral interpolation of the model predictions relative to the scaled Apollo 16 soil spectrum. The accuracy of the model, evaluated against ROLO imagery, was found to be 2-4.