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Full catalog/VNP18A1
VNP18A1·v002·dataset

How much sunlight reaches the ground (VIIRS, Suomi-NPP, daily)

VIIRS/NPP Downward Shortwave Radiation Daily L3 Global 1km SIN Grid V002
land NASA LPCLOUD Level 3 active HDF-EOS5
In plain English

What it measures. Daily maps of how much sunlight energy reaches the ground across land surfaces, covering the full shortwave range of sunlight. It includes total, direct, and scattered light at different times of day.

How it's made. Derived from the VIIRS instrument on the Suomi-NPP satellite, using lookup tables that account for clouds, haze, and sun and viewing angles, then gridded globally at 1-kilometer resolution.

How & where you'd use it. Valuable for land and climate models and increasingly for planning and running solar energy systems, since it shows how much solar power is available where and when.

What's measured

LAND SURFACE › SURFACE RADIATIVE PROPERTIES › REFLECTANCELAND SURFACE › SURFACE RADIATIVE PROPERTIES › ALBEDOLAND SURFACE › SURFACE RADIATIVE PROPERTIES › ANISOTROPYATMOSPHERE › ATMOSPHERIC RADIATION › SHORTWAVE RADIATION

Coverage & cadence

  • Time span2012-01-19 → ongoing
  • Measured bySuomi-NPP (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 VNP18A1 Version 2 is a NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) Visible Infrared Imaging Radiometer Suite (VIIRS) Downward Shortwave Radiation (DSR) gridded Level 3 product. It is produced at 1 kilometer pixel resolution at daily intervals. DSR is the incident solar radiation over land surfaces in the shortwave spectrum (300-4,000 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 DSR. 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 VNP18A1 product are variables for instantaneous total, direct, and diffuse DSR, as well as 3-hour DSR, daily mean DSR, and a quality variable.

Get the data

vnp18a1_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="VNP18A1",
    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.