VIIRS/NPP Photosynthetically Active Radiation Daily L3 Global 1km SIN Grid V002

The VNP18A2 Version 2 is a NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Photosynthetically Active Radiation (PAR) gridded Level 3 product. It is produced at 1 kilometer pixel resolution at daily intervals. PAR is the incident solar radiation in the visible spectrum (400-700 nanometers) and is a significant variable in land surface models (LSMs), receiving increased attention due to its importance for the management and operation of solar energy systems.

The VNP18 algorithm adapts the narrowband look-up table (LUT) approach to estimate PAR. The LUTs consider different types of loadings of aerosols and clouds at a variety of illumination and viewing geometry. The Algorithm Theoretical Basis Document (ATBD) is forthcoming and will provide additional details regarding the methodology used to create the data.

Provided in the VNP18A2 product are variables for instantaneous total, direct, and diffuse PAR, as well as 3-hour PAR, daily mean PAR, and a quality variable.