An Overview of NOAA-21 VIIRS Early On-orbit Calibration and Performance

The third VIIRS instrument, launched onboard the JPSS-2 satellite (also referred to as the NOAA-21) on November 10, 2022, is currently operated in a fleet that includes the S-NPP and NOAA-20 satellites that were launched on October 28, 2011 and November 18, 2017, respectively. In this paper, we provide an overview of NOAA-21 VIIRS initial on-orbit operation and calibration activities and a comprehensive assessment of its early on-orbit performance, including analyses made during its initial post-launch testing phase as well as under current nominal operations. The instrument performance examples presented in this paper include but are not limited to its detector signal-to-noise ratios for the reflective solar bands, the noise equivalent temperature difference for the thermal emissive bands, on-orbit changes of its spectral band responses, and the performance of its on-board calibrators, such as solar diffuser on-orbit degradation and blackbody temperature stability and uniformity. Also discussed in this paper are comparisons of NOAA-21 VIIRS on-orbit performance with its predecessors on-board the S-NPP and NOAA-20 satellites over the same operating period, as well as potential improvements for NOAA-21 VIIRS as its mission continues.