Abstract
The VIIRS has 22 spectral bands: 14 reflective solar bands (RSB), 7 thermal emissive bands (TEB), and 1 day-night band (DNB). The DNB, with a broad banwidth of 500-900 nm, can sense reflected light from space during both day and nighttime, covering an extreme large dynamic range by collecting data at three different gain stages: low gain (LG), mid gain (MG), and high gain (HG). Apart from a broad range of remote sensing applications facilitated by the VIIRS RSB and TEB observations, its DNB nighttime observations have also enabled a number of unique applications, including monitoring and assessment of the trends or patterns of city lights, nighttime fires, fishing boats, and aurora borealis. In this paper, we present the use of celestial objects for the VIIRS DNB on-orbit calibration. Specifically, the use of a sunlit diffuser plate for its LG calibration and gain ratios of its MG to LG and HG to MG, the use of the moon for its LG and stars for its HG stability monitoring are illustrated. Also discussed are existing challenges and limits to different approaches, various strategies and data analysis techniques to carry out these tasks, and results of DNB calibration inter-comparisons among three VIIRS instruments currently operated on the S-NPP, NOAA-20, and NOAA-21.
Use of Celestial Objects for VIIRS Day-Night Band On-orbit Calibration
The VIIRS has 22 spectral bands: 14 reflective solar bands (RSB), 7 thermal emissive bands (TEB), and 1 day-night band (DNB). The DNB, with a broad banwidth of 500-900 nm, can sense reflected light from space during both day and nighttime, covering an extreme large dynamic range by collecting data at three different gain stages: low gain (LG), mid gain (MG), and high gain (HG). Apart from a broad range of remote sensing applications facilitated by the VIIRS RSB and TEB observations, its DNB nighttime observations have also enabled a number of unique applications, including monitoring and assessment of the trends or patterns of city lights, nighttime fires, fishing boats, and aurora borealis. In this paper, we present the use of celestial objects for the VIIRS DNB on-orbit calibration. Specifically, the use of a sunlit diffuser plate for its LG calibration and gain ratios of its MG to LG and HG to MG, the use of the moon for its LG and stars for its HG stability monitoring are illustrated. Also discussed are existing challenges and limits to different approaches, various strategies and data analysis techniques to carry out these tasks, and results of DNB calibration inter-comparisons among three VIIRS instruments currently operated on the S-NPP, NOAA-20, and NOAA-21.