Prelaunch radiometric calibration of the J4 VIIRS reflective solar bands

The Joint Polar Satellite System 4 (JPSS-4) Visible Infrared Imaging Radiometer Suite (VIIRS) instrument is the fifth in a series (S-NPP VIIRS, JPSS-1,2,3 VIIRS) of highly advanced polar-orbiting environmental satellites. JPSS-4 VIIRS underwent a comprehensive sensor-level Thermal Vacuum (TVAC) testing at the Raytheon Technologies El Segundo facility in the fall of 2023. While the test program provided characterization for many spatial, spectral, and radiometric aspects of the VIIRS sensor performance, this paper focuses on the radiometric performance of the 14 reflective solar bands (RSB) that cover the wavelength range from 0.41 to 2.3 μm. Key calibration parameters, such as the instrument gain, signal-to-noise ratio (SNR), dynamic range and radiometric uniformity, were derived in a TVAC environment for both the primary and redundant electronics at three instrument temperature plateaus: cold, nominal, and hot. This paper shows that all the JPSS-4 VIIRS RSB detectors have been well characterized, with the key performance metrics being comparable to those of the previous VIIRS instruments. Comparison of radiometric performance to sensor requirements, as well as a summary of key sensor testing and performance issues, will also be presented.