The exit of EOS Aqua from the A-train in early 2023 marks the end of 20 years of Atmospheric Infrared Sounder (AIRS) data from the 1:30 PM ascending node orbit. The AIRS 20-year data record shows impressive accuracy and stability. Trends in the radiometry relative to accepted stable geophysical references are at the -3 to +6 mK/yr level, likely caused by unaccounted for changes in the lower troposphere and increasing sensor aging effects. Previously unknown trends are seen in the distribution of clouds. The planned continuation of the AIRS data record with potentially 20 years of multiple Cross-track Infrared Sounder (CrIS) instruments may be used to confirm these trends. The overlap of three years of AIRS, SNPP-CrIS and JPSS1-CrIS shows radiometric agreement under cloud free ocean conditions at the 50 mK level. However, there are large day/night, land/ocean and cloud dependent differences between AIRS and CrIS data, which, even if explained by known footprint size differences, will complicate the climate change interpretation of trends from potentially 40 years of concatenated data.
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