An overview of S-NPP VIIRS lunar calibration

The S-NPP VIIRS has operated for more than 3.5 years since its launch in October 2011. The VIIRS reflective solar bands (RSB) calibration is performed by an on-board solar diffuser (SD) and a solar diffuser stability monitor (SDSM). In addition, lunar observations have been used to monitor the RSB on-orbit calibration stability. Since launch, more than 30 lunar calibration events have been scheduled and successfully implemented. This paper provides an overview of S-NPP VIIRS lunar calibration strategies and methodologies. It presents and compares the calibration results derived from regularly scheduled lunar observations with those derived from on-board SD observations. The differences between the solar and lunar calibrations and their likely causes are carefully examined and discussed as an effort for future improvements.