VIIRS reflective solar bands on-orbit calibration using the moon

The Visible Infrared Imager Radiometer Suite (VIIRS) has been on-orbit for more than three and half years. It has been scheduled to view the moon approximately monthly since its nadir door open on November 21, 2011. The scheduled lunar observations have been used to monitor the VIIRS reflective solar bands (RSB) on-orbit gain changes. The VIIRS RSB are primarily calibrated by an onboard Solar Diffuser (SD) panel and an accompanying Solar Diffuser Stability Monitor (SDSM). Due to non-uniformity of the SD degradation, the SD/SDSM calibration may have non-negligible errors, especially for the short wavelength bands. Since lunar surface is very stable, the Moon can be used to provide more reliable on-orbit long-term gain changes of the RSB. The RSB calibration coefficients derived from the lunar calibration are generally consistent with those derived from the SD/SDSM calibration, but clear differences in trend are seen, especially for the short wavelength bands.