VJ202MOD is the short-name for the Joint Polar Satellite System-2 (JPSS-2/NOAA-21; referred to hereafter as J2) platform-derived NASA VIIRS L1B calibrated radiances product that contains 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. The data product described in this landing page is a v2.1 collection and its data record starts from February 10, 2023.

Radiometric Calibration-specific changes
The following updates define the changes implemented in the v2.1 collections:

1. Applied the Total and Spectral Solar Irradiance Sensor-1 (TSIS-1) solar spectral irradiance.
2. Improved screen functions derived from yaw maneuvers combined with regular on-orbit solar diffuser calibration data.
3. Addressed the time-dependent striping mitigation for Visible Near Infrared bands M1-M3.
4. Updated the Delta-C look-up table (LUT) to correct the M4 low-gain error in the pre-launch LUT.
5. The recently available Day-Night Band (DNB) Mid-Gain State (MGS) Relative Spectral Response (RSR) is applied to High-Gain State (HGS) and MGS calibration, which previously only used the Low-Gain State (LGS) RSR in the earlier version v3.2.3.x.

Radiometric Accuracy Radiometric accuracy forms a key requirement that enables us to derive good quality L2 retrievals and provide the basis for higher-level products. The v2.1 J2 VIIRS L1 product’s radiometric accuracies for the RSB and TEB spectral band groups are as follows:

Reflective Solar Bands: Based on the VIIRS Sensor Specifications, the VIIRS reflective solar bands’ calibration uncertainty for spectral reflectance over a scene with typical radiance is defined at less than 2%.

Thermal Emissive Bands: Given a uniform scene with 267 K brightness temperature (for image and emissive bands), the specified calibration uncertainty for spectral radiance is defined at 5% for Image band-4 and 2.5% for Image band-5.