The Suomi National Polar-orbiting Partnership (SNPP) Visible Infrared Imaging Radiometer Suite (VIIRS) supports a Day-Night Band (DNB) sensor that provides global daily measurements of nocturnal visible and near-infrared (NIR) light that are suitable for Earth system science and applications. The VIIRS DNB’s ultra-sensitivity in lowlight conditions enable us to generate a new set of science-quality nighttime products that manifest substantial improvements in sensor resolution and calibration when compared to the previous era of Defense Meteorological Satellite Program/Operational Linescan System’s (DMSP/OLS) nighttime lights image products. Such improvements allow the VIIRS DNB products to better monitor both the magnitude and signature of nighttime phenomena, and anthropogenic sources of light emissions.

VNP46A3 is the short-name for the monthly composited, moonlight- and atmosphere-corrected Nighttime Lights (NTL) product whose long-name is VIIRS/NPP Lunar BRDF-Adjusted Nighttime Lights Monthly L3 Global 15 arc second Linear Lat Lon Grid.

Version Description

This version 2.0 (v2.0) monthly product is generated using inputs from both the v2.0 daily Nighttime Lights input products: VIIRS/NPP Daily Gridded Day-Night Band 15 arc-second Linear Lat Lon Grid Night (VNP46A1) and VIIRS/NPP Gap-Filled Lunar BRDF-Adjusted Nighttime Lights Daily Level 3 Global 15 arc-second Linear Lat Lon Grid (VNP46A2). Key changes and differences in the v2.0 collection relative to the v1.0 collection include the following:

1. The v2.0 Day-Night Band (DNB) radiance data format has changed from unsigned integer in version 1.0 (v1.0) to floating-point format to prevent saturation in cases such as extremely bright gas flares with radiance values exceeding 6553.5 nW·cm⁻²·sr⁻¹. The maximum value for an unsigned integer format is 65535.
2. The v1.0 VNP46A1 and VNP46A2 collections are produced exclusively for land surfaces, whereas for v2.0 collections, they are generated for both land and water surfaces.
3. In the daily-produced v2.0 VNP46A2 collection, the product’s Mandatory_Quality_flag layer has been updated to 0 for high quality and 1-5 for poor quality. Besides, the v2.0 Mandatory_Quality_flag includes additions for lunar eclipse (qa=3), aurora (qa=4), and glint (qa=5). In v1.0, the Black Marble products are generated with solar zenith angles greater than 108 degrees. In the new v2.0, the range is expanded to include solar zenith angles greater than 102 degrees. Also, the quality for solar zenith angles between 102 and 108 degrees is assigned a value of 2 in the Mandatory_Quality_flag.
4. The SNPP DNB experienced degradation after launch, whereas the NOAA-20 and NOAA-21 DNB have remained stable. In v2.0, the yearly DNB spectral response functions are applied to the SNPP Black Marble product.

The v2.0 VNP46A3 collection is provided in standard Hierarchical Data Format–Earth Observing System (HDF-EOS5) format and starts from January 1, 2012. This product has been validated through various field campaigns of opportunity supported under the Group on Earth Observations (GEO) Human Planet Initiative’s Nighttime Product Validation (NPV) task. Additionally, the VNP46 product suite comes with ancillary and quality assessment layers indicating sources of error from the calibration, cloud mask, snow flag, and lunar irradiance, etc.

Science Data Sets (SDS):

1. Temporal radiance composite using all observations during snow-covered period
2. Number of observations of temporal radiance composite using all observations during snow-covered period
3. Quality flag of temporal radiance composite using all observations during snow-covered period
4. Standard deviation of temporal radiance composite using all observations during snow-covered period
5. Temporal radiance composite using all observations during snow-free period
6. Number of observations of temporal radiance composite using all observations during snow-free period
7. Quality flag of temporal radiance composite using all observations during snow-free period
8. Standard deviation of temporal radiance composite using all observations during snow-free period
9. Day-Night Band Platform
10. Temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-covered period
11. Number of observations of temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-covered period
12. Quality flag of temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-covered period
13. Standard deviation of temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-covered period
14. Temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-free period
15. Number of observations of temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-free period
16. Quality flag of temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-free period
17. Standard deviation of temporal radiance composite using near-nadir angle observations (view-zenith angle 0-20 degree) during snow-free period
18. Temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-covered period
19. Number of observations of temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-covered period
20. Quality flag of temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-covered period
21. Standard deviation of temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-covered period
22. Temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-free period
23. Number of observations of temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-free period
24. Quality flag of temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-free period
25. Standard deviation of temporal radiance composite using off-nadir angle observations (view-zenith angle 40-60 degree) during snow-free period
26. Land-Water Mask
27. Latitude
28. Longitude

Processing Chain Provenance

This section instructs users regarding where to find the source locations for three provenance-specific information artifacts in the global metadata attributes.

Processing steps used to generate the SNPP VIIRS VNP46 product: The data product inputs, the algorithm processing flow, and all other pertinent details that help create the VIIRS Nighttime Lights products are described in the following two sources:

1. The Black Marble User Guide (Version 2.0, October 2024)
2. The Black Marble Algorithm Theoretical Basis Document (Version 1.1, July 2020)

The data producer’s name and email: This information is available in the global metadata attributes.

The production software (PGE) version used: The processing software used to generate the product is called a Product Generation Executable or PGE, and is identified via the following two pieces of information in the global metadata attributes:

1. PGE_Name, which is an alphanumeric value, e.g., “PGE554”
2. PGE Version, which is a numeric value, e.g., “1.0.10”

The PGE name and its version help associate the exact production software that was used to generate any specific version of the data product.