The VNP46A2 Daily Moonlight-adjusted Nighttime Lights (NTL) Product


Both VNP46 products use the standard suite of VIIRS land products as input and are integrated as part of NASA's Black Marble processing chain which contains both daytime and nighttime branches. For the daytime branch, a modified version of the operational VIIRS surface reflectance algorithm (Roger et al., 2016; Vermote et al., 2014) is used to generate the DNB surface bidirectional reflectance factor (BRF) using NASA's Level 1B calibrated radiance product as input (i.e., 6-minute granules, or 2366km along track and ~3100km across-track). Level 2G DNB surface reflectance is then generated by performing spatial and temporal aggregation to 500m grid cells over daily time periods (Campagnolo et al., 2016; Pahlevan et al., 2017; Wolfe et al., 1998; Yang and Wolfe, 2001). Daily Level 3 DNB BRDF/Albedo data are then retrieved using the heritage MODIS/VIIRS algorithm (MCD43/VNP43) (Liu et al., 2017, Liu et al., 2017; Wang et al., 2018), and corresponding snow flags are estimated using the VIIRS Normalized Difference Snow Index (NDSI) algorithm (VNP10) (Riggs et al., 2016, Riggs et al., 2017). The NDVI and NDSI values are used to determine the growing, dormant, and snow periods to routinely update the a priori global database of the DNB BRDF product (Cescatti et al., 2012; Liu et al., 2017, Liu et al., 2017; Román et al., 2009). Surface bidirectional reflectance factor from the VIIRS I1 (red) and I2 (NIR) channels is used to obtain daily estimates of LAI (Knyazikhin et al., 1999; Park et al., 2017; Xiao et al., 2016). The retrieved leaf area index and clumping index values are then used to calculate the gap fraction probability (Pgap).

Input File Description
VNP46A1 VIIRS/NPP Daily Gridded Day Night Band 500m Linear Lat Lon Grid Night
VNP43LGDNBA1 VIIRS/NPP DNB BRDF/Albedo Model Parameters Daily L3 Global 500m LLL Grid
VNPPLG09GA VIIRS/NPP Surface Reflectance Daily L2G Global 1km and 500m Linear Lat Lon Grid
VNP04LGA VIIRS/NPP Aerosols Optical Thickness Daily L2G Global Linear Lat Lon Grid


The daily moonlight and atmosphere corrected NTL (VNP46A2) is available at 500m resolution from January 2012-present. The VNP46A2 product has 6 layers containing information on BRDF-corrected NTL (500m), lunar irradiance, mandatory quality flag, latest high-quality retrieval (number of days), snow flag, and cloud mask flag. The table below details the information within the product layers.

Scientific Datasets
(SDS HDF Layers)
Units Description Bit Types Fill Value Valid Range Scale Factor Offset
DNB_BRDF-Corrected_NTL_500m nWatts cm-2 sr-1 BRDF corrected DNB NTL 16-bit unsigned integer 65535 0 - 65534 0.1 0.0
DNB_Lunar_Irradiance nWatts cm-2 sr-1 DNB Lunar Irradiance 16-bit unsigned integer 65535 0 - 65535 0.1 0.0
Mandatory_Quality_Flag Unitless Mandatory quality flab 8-bit unsigned integer 255 0 - 3 N/A N/A
Latest_High_Quality_Retrieval Number of days Latest high quality BRDF corrected DNB radiance retrievel 8-bit unsigned integer 255 0 - 254 1.0 0,0
Snow_Flag Unitless Flag for snow cover 8-bit unsigned integer< 255 0 - 1 N/A N/A
QF_Cloud_Mask Unitless Quality flag for cloud mask 16-bit unsigned integer 65535 0 - 65534 N/A N/A


VNP46 product suite components for a 10° x 10° Level 3 tile over Sweden and Finland (h20v02; DOY 2013-080). The half-moon-illuminated and 30% cloud-contaminated scene is shown to capture extraneous light emissions north of the Gulf of Bothnia caused by the Aurora Borealis.
VNP46 product suite components for a 10 ° X 10 ° Level 3 tile over Sweden and Finland (h20v02; DOY 2013-080). The half-moon-illuminated and 30% cloud-contaminated scene is shown to capture extraneous light emissions north of the Gulf of Bothnia caused by the Aurora Borealis.