The Cross-track Infrared Sounder (CrIS) Level 1B Full Spectral Resolution (FSR) data files contain radiance measurements along with ancillary spacecraft, instrument, and geolocation data of the CrIS instrument on the Joint Polar Satellite System-2 (JPSS-2) platform. This platform is also know as NOAA-21 (National Oceanic and Atmospheric Administration).

The IMG product supplements the CrIS Level 1B (L1B) hyperspectral radiance product by providing collocated high-spatial resolution data from the Visible Infrared Imaging Radiometer Suite (VIIRS) imager located on the same platform. VIIRS radiance and cloud mask values are grouped and aggregated for every CrIS field of view (FOV) and made available in a format intended for use alongside the CrIS L1B data. The collocated VIIRS level 1 / cloud mask statistical summary (collection name SNDRJ2CrISL1BIMG) is the main product and consists of collocated CrIS field of views with the VIIRS cloud mask and radiances/reflectances. This can be thought of as a match-up between CrIS and VIIRS. The supplementary product, array indices for collocated VIIRS observations (SNDRJ2CrISL1BIMGC), product additionally makes available CrIS and VIIRS data array index values that result from the collocation process that is performed as part of producing IMG. These index values can be leveraged by end users to further augment CrIS data by extracting collocated observations from any additional VIIRS data products that aren’t already present in IMG.

The FSR files have 2,223 channels (2211 apodized channels): 637 (633) shortwave channels from 3.9 to 4.7 microns (2555 to 2150 cm-1), 869 (865) midwave channels from 5.7 to 8.05 microns (1752.5 to 1242.5 cm-1), and 717 (713)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.

The Visible Infrared Imaging Radiometer Suite (VIIRS) has 22 imaging and radiometric bands covering wavelengths from 0.41 to 12.5 microns. It provides the sensor data records for clouds, sea surface temperature, ocean color, and others. This IMG_COL product contains the colocation indices of the VIIRS pixels within each CrIS footprint.