NOAA-21

NOAA-21, launched as JPSS-2 on 10 November 2022, is the second flight unit of the Joint Polar Satellite System. It became NOAA’s primary afternoon polar-orbiting weather satellite on 20 March 2024. ATMS and CrIS provide microwave and infrared sounding observations, VIIRS supplies visible and infrared imagery, and OMPS measures atmospheric ozone with nadir and limb components. These complementary measurements support numerical weather prediction, atmospheric chemistry and climate monitoring. Unlike Suomi NPP and NOAA-20, NOAA-21 does not carry CERES; Earth-radiation continuity should therefore not be inferred from membership in the JPSS fleet alone.