VJ202MOD - VIIRS/JPSS2 Moderate Resolution 6-Min L1B Swath 750m

VJ202MOD is the short-name for the Joint Polar-orbiting Satellite System-2 (JPSS-2/NOAA-21; referred to hereafter as J2) platform-derived NASA VIIRS L1B calibrated radiances product that comprises sixteen moderate-resolution or M-bands, which have a spatial resolution of 750-meters at nadir. These M-bands comprise eleven reflective solar bands (RSB) and five thermal emissive bands (TEB). Each of the M-bands has 16 detectors in the along-track direction with 16 rows of pixels per scan that provide a 750-m resolution. Ranging in wavelengths from 0.402 µm to 12.49 µm, the M-bands are sensitive to visible, near-, shortwave-, mediumwave-, and longwave-infrared wavelengths. Derived from the NASA VIIRS L1A raw radiances, this product includes calibrated and geolocated radiance and reflectance data, quality flags, and granule- and collection-level metadata. In contrast to a MODIS L1B product, which temporally spans 5 minutes, the VIIRS L1B calibrated radiances product contains a nominal temporal duration of 6 minutes. The image dimensions of the 750-m swath product measure 3232 lines by 3200 pixels.

Radiometric Calibration-specific changes
The J2 VIIRS radiometric calibration Level-1B reprocessing includes a few calibration updates for the reflective solar bands (RSB), but no significant changes for the day-night band (DNB) or thermal emissive bands (TEB). The RSB updates include the following:

1. An estimated time-dependent adjustment is applied to the VIS/NIR band solar diffuser (SD) F-factors before generating the F-Predicted LUTs to correct for the expected long-term drift in the SD calibration. The estimated adjustment is the average of the S-NPP and J1 (NOAA-20) adjustments derived from comparing SD and lunar trends for S-NPP and J1. This estimated approach is used since there is not yet enough J2 lunar data to derive an adjustment directly for J2.
2. The accuracy of the F-Predicted LUTs for the SWIR bands is improved in the reprocessed time series by fitting the measured SD F-factors (which show rapid gain changes for some SWIR detectors) to smooth functions to remove the forward-prediction errors.
3. A scale factor of 6.1% is applied to the M11 reflectance and radiance values consistently over the entire mission to improve the agreement between J1 and J2 reflectances at this wavelength.