VIIRS DNB HGS Radiometric Calibration Source

A new radiometric vicarious calibration approach for the Suomi NPP VIIRS Day/Night Band’s (DNB) high gain stage (HGS) is proposed that will complement traditional, extended source, radiance-based calibrations, which are based on natural lunar illumination and not as accurate as desired. The proposed research will produce affordable, field-deployable, NIST-traceable point source lamps that can achieve HGS DNB radiance per pixel with a long-term, post-correction source stability of better than 1%. Using radiative transfer modeling and VIIRS DNB characteristics, the top-of-atmosphere absolute radiometric accuracy will be better than 5% under clear sky conditions. The artificial source’s spectral distribution can be made similar to that of natural lunar illuminated scenes to ensure this new approach is compatible with ongoing lunar illumination-based vicarious radiometric calibrations. Other spectral distributions can also be produced if needed. To increase energy efficiency and reliability, the source will be remotely controlled and monitored. The source will only turn on during the VIIRS DNB site overpass, when observation conditions are optimal. Built-in lamp sensors will provide lamp health information and auxiliary sensors will provide site environmental conditions. This new approach should be applicable to other nighttime imagers and will help calibrate other point sources observed by VIIRS.