Version 4 is the current version of this dataset and supersedes previous versions (Version 1, 2, 3). Please see Version Description for more information about these changes.

The Cross-track Infrared Sounder (CrIS) Level 1B Normal Spectral Resolution (NSR) data files contain radiance measurements along with ancillary spacecraft, instrument, and geolocation data for the CrIS instrument on the Suomi National Polar-orbiting Partnership Project (SNPP) satellite. In December 2014, the spectral resolution of data transmitted to the ground from the SNPP CrIS instrument was increased by a factor of two in the midwave infrared band, and by a factor of four in the shortwave infrared band. In November 2015, additional points were included at the ends of the longwave and shortwave SNPP CrIS interferograms to improve calibration quality. Prior to November 2, 2015 at 16:06 UTC, SNPP CrIS data are only available in NSR. After that time, the SNPP CrIS data are available in both NSR and Full Spectral Resolution (FSR). JPSS-1 and JPSS-2 CrIS data are only provided in FSR.

The NSR files have 1,317 channels: 163 shortwave channels from 3.9 to 4.7 microns (2555 to 2150 cm-1), 437 midwave channels from 5.7 to 8.05 microns (1752.5 to 1242.5 cm-1), and 717 longwave channels from 9.1 to 15.41 microns (1096.25 to 648.75 cm-1). Each CrIS field-of-regard (FOR) contains 9 field-of-views (FOVs) arranged in a 3X3 array. The Level 1B files contain 30 FORs in the cross-track direction and 45 in the along-track direction. Data products are constructed on six-minute boundaries.

CrIS data are designed to be used with the ATMS (Advanced Technology Microwave Sounder) instrument data. These instruments together are referred to as CrIMSS (Cross-track Infrared and Microwave Sounder Suite).