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Full catalog/VIIRSN_L3m_PAR
VIIRSN_L3m_PAR·v2022.0·dataset

Sunlight available for ocean plants (VIIRS, Suomi-NPP)

Suomi-NPP VIIRS Level-3 Global Mapped Photosynthetically Available Radiation (PAR) Data, version 2022.0
ocean NASA OB_CLOUD Level 3 active netCDF-4
In plain English

What it measures. How much sunlight in the wavelengths plants use for photosynthesis reaches the ocean surface, given as a daily global map.

How it's made. Estimated from ocean-color measurements by the VIIRS instrument on the Suomi-NPP satellite, then averaged onto a regular worldwide grid.

How & where you'd use it. Estimating how much tiny ocean plants can grow, interpreting algae blooms, and feeding ecosystem and carbon studies.

What's measured

Oceans › Ocean Optics › Photosynthetically Active Radiation

Coverage & cadence

  • Time span2012-01-02 → ongoing
  • Measured bySuomi-NPP (VIIRS)
  • Processing levelLevel 3
  • Spatial extent-180, -90, 180, 90
  • FormatsnetCDF-4
  • StatusACTIVE

What you can do with it

  • Watch sea-surface temperature and marine heatwaves
  • Spot algal blooms and ocean-colour shifts
  • Support fisheries and coastal monitoring
Official description

The Photosynthetically Available Radiation (PAR) data suite provides satellite-based estimates of the downwelling solar radiation in the 400–700 nm range that is available for photosynthesis at the ocean surface. These products quantify the daily or instantaneous amount of usable light energy, expressed in moles of photons m⁻² (commonly noted as “Einstein m⁻²”), and are widely used to estimate marine primary production, interpret phytoplankton bloom dynamics, provide context for optical and biogeochemical measurements,and support ecosystem models and education on light–biology interactions. Geophysical variables in this suite include: - par — Daily photosynthetically available radiation (mol photons m⁻² d⁻¹)

Get the data

viirsn_l3m_par_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="VIIRSN_L3m_PAR",
    version="2022.0",
    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 OB_CLOUD
Browsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.