Suomi NPP/JPSS Cross-track Infrared Sounder (CrIS): Radiometric and Spectral Performance

The path from research to operations for high spectral resolution infrared sounding has made a major step forward with the flight of CrIS on Suomi NPP. This path dates back to the mid-1980s when retrievals from High-resolution Interferometer Sounder (HIS) aircraft data first demonstrated the significantly increased vertical resolution for temperature and water vapor soundings (factor of 2.5-3 higher) made possible by higher spectral resolution. The HIS spurred a 1990/91 Phase-A instrument design by a team led by the University of Wisconsin-Madison (sponsored by EUMETSAT) that fostered more detailed designs by Excelis(then ITT)/ABB(then Bomem) and inclusion on NPP starting in the mid 1990s. Now we have the start of an operational series (Joint Polar Satellite Series, JPSS) with sounding from the 930 morning orbit being covered by IASI on MetOP and from the 1330 orbit by CrIS, which will operationalize the EOS Aqua research capability from the Atmospheric IR Sounder (AIRS). Detailed characterization of the calibration and overall performance is one of the key aspects needed for successful forecast model assimilation and impact on operations. An overview of what has been learned from CrIS Calibration and Validation activities will be presented. In summary, all of the radiometric and spectral performance specifications for CrIS have been met and the fundamental calibration accuracy and noise performance specifications have been significantly exceeded. The current state of characterization efforts and uncertainty budgets will be presented. It is clear that the advantages for weather forecasting and climate demonstrated for AIRS and IASI predecessor observations will be matched or exceeded by CrIS.