S-NPP VIIRS On-Orbit Performance and Calibration Improvements

The first VIIRS instrument was launched on-board the S-NPP satellite in October 2011. It has successfully operated and continued to deliver high quality data products to support both operational and research communities for their applications and scientific studies. The VIIRS observations are made in 22 spectral bands, spanning a wavelength range from 0.41 to 12.4 μm. It includes a day/night band (DNB) that can make observations in three gain stages, thus covering an extremely large dynamic range. The VIIRS reflective solar bands (RSB) are calibrated primarily by a solar diffuser (SD) and solar diffuser stability monitor (SDSM) system, coupled together with regularly scheduled lunar observations. Its thermal emissive bands (TEB) calibration is performed using an on-board blackbody (BB), nominally controlled at a constant temperature and commended on a quarterly basis by varying its temperatures from instrument ambient to up to 315 K. This paper provides a brief overview of S-NPP VIIRS on-orbit operation and calibration activities, strategies, and methodologies, and an update of its overall performance. It will focus on various challenging issues and, especially, the latest calibration improvements resulting from joint efforts made by the NASA and NOAA calibration groups to ensure and enhance the SDR data quality. Also included are discussions on several key contributors and their impact on the VIIRS SDR quality and on-orbit calibration uncertainties.