The radiometric and spectral consistency among the Atmospheric InfraredSounder (AIRS), the Infrared Atmospheric Sounding Interferometer (IASI), andthe Cross-track Infrared Sounder (CrIS) is fundamental for the creation oflong-term infrared (IR) hyperspectral radiance benchmark data sets for bothintercalibration and climate-related studies. In this study, the CrISradiance measurements on Suomi National Polar-orbiting Partnership (SNPP)satellite are directly compared with IASI on MetOp-A and MetOp-B at the finest spectralscale and with AIRS on Aqua in 25 selected spectral regions through simultaneousnadir overpass (SNO) observations in 2013, to evaluate radiometricconsistency of these four hyperspectral IR sounders. The spectra fromdifferent sounders are paired together through strict spatial and temporalcollocation. The uniform scenes are selected by examining the collocatedVisible Infrared Imaging Radiometer Suite (VIIRS) pixels. Their brightnesstemperature (BT) differences are then calculated by converting the spectraonto common spectral grids. The results indicate that CrIS agrees well withIASI on MetOp-A and IASI on MetOp-B at the long-wave IR (LWIR) and middle-wave IR (MWIR)bands with 0.1–0.2 K differences. There are no apparent scene-dependentpatterns for BT differences between CrIS and IASI for individual spectralchannels. CrIS and AIRS are compared at the 25 spectral regions for bothpolar and tropical SNOs. The combined global SNO data sets indicate that theCrIS–AIRS BT differences are less than or around 0.1 K among 21 of 25spectral regions and they range from 0.15 to 0.21 K in the remaining fourspectral regions. CrIS–AIRS BT differences in some comparison spectralregions show weak scene-dependent features.
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