NOAA-21 VIIRS on-Orbit Calibration Performance: Year 1

The NOAA-21 (N-21) VIIRS has successfully operated for more than 1 year since its launch on November 10, 2022. This paper provides a comprehensive assessment of its on-orbit performance based on measurements made during its initial post-launch testing (PLT) and ensuing on-orbit calibration and characterization. Results presented in this paper include performance of its on-board calibrators (OBC), detector noise characteristics, on-orbit changes in its spectral band responses and spatial performance in terms of band-to-band registrations (BBR). In general, the N-21 VIIRS overall performance is comparable to or better than its predecessor S-NPP and N-20 VIIRS, with an exception of large changes in its SWIR band responses at mission beginning. On-orbit assessment also shows a more effective stray light reduction in N-21 day and night band (DNB).