The latest incarnation of the infrared sounder is the Cross-track Infrared Sounder (CrIS). CrIS is one of the mission-critical instruments onboard the Joint Polar Satellite System (JPSS), including the Suomi National Polar-orbiting Partnership (SNPP) weather satellite and JPSS-1. The CrIS instrument collects hyperspectral infrared radiance data over a spectral range from 3.9 to 15.4 microns, with a ground spatial resolution of 14 km at nadir. Its data is used for precise measurements of vertical distributions of temperature, moisture, and pressure within the earth’s atmosphere. The CrIS instrument onboard SNPP has recently completed six years of flawless on-orbit operations.
This past year, the second CrIS instrument completed testing, was integrated with the JPSS-1 satellite, and has been successfully launched. It is now completing on-orbit calibration and validation. Three other CrIS instruments are currently in production for JPSS-2 through JPSS-4.
Infrared sounder data provides critical input to numerical weather prediction (NWP) models and is particularly important in improving the accuracy of global and regional 3-5 day weather forecasts. Other data products from sounders are now starting to be used for climate and commercial applications.
Ongoing research and development is expanding the capabilities of infrared sounders, and reducing the cost of collecting this critical data. This includes options for improved spatial, spectral, and temporal resolution; the use of free-flying small satellites; and/or the use of distributed constellations of CubeSats.
This paper will summarize the development of infrared sounders since the 1970s, describe the technological hurdles that were overcome to provide ever-increasing performance capabilities, and highlight the radiometric performance of the CrIS instrument on JPSS-1 (CrIS-JPSS1). This includes details of the CrIS-JPSS1 measured noise-equivalent spectral radiance (NEdN) performance, radiometric uncertainty performance utilizing a new and improved internal calibration target, short-term and long-term repeatability, spectral uncertainty, and spectral stability. In addition, the full-resolution operating modes for CrIS-JPSS1 will be reviewed, including a discussion of how these modes will be used during on-orbit characterization tests. We will provide a brief update of CrIS-SNPP on-obit performance and the production status of the CrIS instruments for JPSS-2 through JPSS-4. Current technological challenges will also be reviewed, including how ongoing research and development is enabling improvements to future sounders. The expanding usage of infrared sounding data will also be discussed, including demonstration of value via data assimilation, the roles of the public/private sector in communicating the importance of sounding data for long-term observations, and the long road to success from research to operational data products.