The VNP09A1 VIIRS Version 1 data product was decommissioned on April 8th, 2025. Users are encouraged to use Version 2 data products, which provide better calibration and consistency for the end user. VIIRS Version 2 data products are available from both the SNPP (VNP09A1) and NOAA-20 (VJ109A1) satellites.

The 8-day Visible Infrared Imaging Radiometer Suite (VIIRS) surface reflectance (VNP09A1) Version 1 composite product provides an estimate of land surface reflectance from the NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) VIIRS sensor for nine moderate resolution bands (M1 - M5, M7, M8, M10, M11) at nominal 1 kilometer resolution (~926 meter). The 1 kiliometer dataset is derived through resampling the native 750 meter VIIRS resolution in the Level 2 input product. The data are corrected for atmospheric conditions such as the effects of molecular gases, including ozone and water vapor, and for the effects of atmospheric aerosols. Each pixel represents the best possible Level 2G observation during an 8-day period that is selected on the basis of high observation coverage, low sensor angle, the absence of clouds or cloud shadow, and aerosol loading. Included in the product along with the nine reflectance bands are day of year, reflectance band quality, control, reflectance state quality assurance, relative azimuth angle, sensor zenith angle, and solar zenith angle layers.

Known Issues

• The VIIRS Land Surface Reflectance product (VNP09) may incorrectly flag retrievals as "High Aerosol" over brighter surfaces and at higher view angles. This will impact the downstream VIIRS BRDF/Albedo (VNP43) and Vegetation Index (VNP13) data products which use the aerosol quantity flag to screen out high aerosol values.
• Corrections will be implemented in Collection 2 reprocessing in 2022.
• For complete information about known issues please refer to the MODIS/VIIRS Land Quality Assessment website and in Section 4.0 "Caveats and Known Problems" of the User Guide.