MISR abstract

Stone, T.C. and Kieffer, H.H., (2004). On-orbit Calibration of Satellite Instruments Using the Moon. Eos Trans. AGU, 85(47), Fall Meet. Suppl. 2004, Abstract # A33D-0105

The Moon provides a unique and useful target for radiometric calibration of satellite instruments on-orbit. Although the lunar surface is non-uniform and non-Lambertian, it is extremely stable. Thus a model that fits the complex lunar reflectance properties, once established, can be applied to satellite observations of the Moon made at any time. The USGS RObotic Lunar Observatory (ROLO) project has developed a model for the lunar disk-equivalent irradiance,based upon a ground-based observational dataset spanning 6+ years. Irradiance data from $\sim$1200 observations are fitted for each of 32 bands covering wavelengths 350 to 2500~nm and phase angles from near-eclipse to 90 degrees. The empirical model form includes terms to accommodate lunar libration and the opposition effect. The mean absolute fit residual is below 1%. Comparisons against the ROLO model are presented for seven remote sensing imaging instruments: SeaWiFS, Hyperion, ALI, MTI, MODIS-Terra, MISR and ASTER. These results show significant calibration discrepancies among the instruments. Although the absolute calibration of the ROLO data still has some persistent uncertainties, the model supports relative response trending with sub-percent precision. SeaWiFS has observed the Moon nearly monthly since 1997 November. Based on the first 66 lunar observations, a time-dependent correction for SeaWiFS ocean-leaving radiance data has been developed; these trend corrections have residuals $\sim$0.1%. This level of precision achievable with the ROLO lunar irradiance model can meet the long-term stability requirements for climate research data products derived from space-based instrumentation. http://www.moon-cal.org

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