The Cross-track Infrared Sounder (CrIS) instrument on the Suomi National Polar-orbiting Partnership (SNPP) platform developed an anomaly that affects its longwave channels, which started on May 21, 2021 1552 UTC. As a result, the associated bands of the SNPP VIIRS/CrIS Fusion product (version 1.0) will contain fill data. The affected bands in this product are 30–36. The fusion product bands 23–28 are still available.
In support of the primary goal of the Suomi National Polar-orbiting Partnership (SNPP) mission to provide continuity in the portfolio of Earth science data products with those derived from the Earth Observing System (EOS) Terra and Aqua missions, the Visible Infrared Imaging Radiometer Suite (VIIRS) and Cross-track Infrared Sounder (CrIS) Fusion is a novel product. This Level-2 (L2) swath product leverages the VIIRS and CrIS instruments’ assets to create narrowband radiances based on the Aqua Moderate resolution Imaging Spectroradiometer’s (MODIS) spectral response functions. This innovative fusion-based product between an imager and a sounder instrument is necessitated by the VIIRS instrument’s lack of IR bands that are responsive to atmospheric absorption. Using both VIIRS and CrIS inputs, this product helps derive MODIS-equivalent fusion-based radiances for VIIRS in the following absorption regions (the analogue MODIS bands in parenthesis):
- CO2 : Around 4.3 μm (bands 23 – 25) and around 15 µm (bands 33 – 36)
- O3 : Near 9 µm (band 30)
- H2O: Near 6.7 µm (bands 27 and 28)
- 11 µm and 12 µm window (bands 31 and 32)
The L2 VIIRS+CrIS Fusion product has a horizontal pixel size of 750 m, which is the native VIIRS moderate-resolution (M) band pixel-size. The following Science Data Sets (SDS) comprise the primary geophysical data in this L2 product:
||Difference of measured minus fusion-reconstructed VIIRS M15 [M16] brightness temperature.
|MODIS23, MODIS24, MODIS25, MODIS27, MODIS28, MODIS30, MODIS31, MODIS32, MODIS33, MODIS34, MODIS35, MODIS36
||MODIS-equivalent band 23 [24, 25, 27, 28, 30, 31, 32, 33, 34, 35, 36] earth view fusion radiance
|MODIS23_brightness_temperature_lut [24, 25, 27, 28, 30, 31, 32, 33, 34, 35, 36]
||MODIS band 23 [24, 25, 27, 28, 30, 31, 32, 33, 34, 35, 36] equivalent brightness temperature lookup table (Aqua)
Consult the VIIRS+CrIS Fusion product user guide for additional information regarding this product’s algorithm, file format, global and data-field attributes, quality control flags, etc.