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Full catalog/VJ118A2
VJ118A2·v002·dataset

How much sunlight reaches plants, daily (VIIRS NOAA-20, 1 km)

VIIRS/JPSS1 Photosynthetically Active Radiation Daily L3 Global 1km SIN Grid V002
land NASA LPCLOUD Level 3 active HDF-EOS5
In plain English

What it measures. How much visible sunlight reaches the land surface each day, the light in the range that plants use for photosynthesis. Values come as daily maps at about 1-kilometer detail.

How it's made. Calculated from the VIIRS instrument on the NOAA-20 satellite, using look-up tables that account for clouds, haze, and viewing angle to estimate the incoming light.

How & where you'd use it. Feeds models of plant growth and carbon uptake, and is increasingly used to plan and operate solar energy systems.

What's measured

LAND SURFACE › SURFACE RADIATIVE PROPERTIES › REFLECTANCELAND SURFACE › SURFACE RADIATIVE PROPERTIES › ALBEDOLAND SURFACE › SURFACE RADIATIVE PROPERTIES › ANISOTROPY

Coverage & cadence

  • Time span2018-01-05 → ongoing
  • Measured byNOAA-20 (VIIRS)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsHDF-EOS5
  • StatusACTIVE

What you can do with it

  • Track deforestation, fire scars and land-cover change
  • Monitor crop and vegetation health (NDVI/EVI)
  • Map how built-up vs. green an area is over time
Official description

The NOAA-20 Visible Infrared Imaging Radiometer Suite (VIIRS) Photosynthetically Active Radiation (PAR) gridded Level 3 product 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 VJ118 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/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 VJ118A2 product are variables for instantaneous total, direct, and diffuse PAR, as well as 3-hour PAR, daily mean PAR, and a quality variable.

Get the data

vj118a2_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="VJ118A2",
    version="002",
    bounding_box=(-122.5, 37.2, -121.8, 37.9),  # your area (W,S,E,N)
    temporal=("2024-01-01", "2024-12-31"),       # your dates
)
files = earthaccess.open(results)   # stream straight from LPCLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.