Update of JPSS-2 VIIRS Prelaunch Calibration and Characterization Performance

Two nearly identical Visible Infrared Imaging Radiometer Suite (VIIRS) instruments are currently operated in the same polar orbit, one on-board the Suomi NPP spacecraft launched in October 2011 and another on-board the NOAA-20 spacecraft launched in November 2017, with NOAA-20 orbiting about 50 minutes ahead of Suomi NPP. The VIIRS makes global observations of various land, ocean, and atmosphere parameters at high temporal resolution with 22 spectral bands covering wavelengths from 0.41 to 12.2 microns and at 2 spatial resolutions: 375 and 750 m (nadir). It also includes a day-night band (DNB) that can make measurements over a very large dynamic range at three different gain stages. The third VIIRS flight unit will be on-board the JPSS-2 (J2) satellite. To date, it has already completed all phases of its sensor-level pre-launch calibration and characterization and successfully passed the Pre-Ship Review (PSR). Additional testing will be performed when the VIIRS is integrated with other sensors on the spacecraft prior to its launch, currently scheduled for 2022. As expected, the VIIRS instrument calibration and performance have direct impact on the quality of its sensor data records (SDRs) and, consequently, all the environmental data records (EDRs) that use SDR as key input for data production. Many of the critical parameters used for on-orbit calibration are characterized and derived from pre-launch measurements. In this paper, we provide an update of J2 VIIRS pre-launch calibration and characterization activities. It discusses efforts made by the instrument vendor and the joint government team to improve sensor pre-launch calibration and its performance assessments based on lessons learned from different testing phases and that from S-NPP and JPSS-1 (J1) VIIRS testing. Pre-launch performance results of J2 VIIRS and comparisons with SNPP and J1 VIIRS are also presented and discussed with a focus on some of the key radiometric performance parameters, such as detector signal-to-noise ratios (SNR), response dynamic range, relative spectral response (RSR), response versus scan-angle (RVS), and polarization sensitivity.