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Full catalog/MODIST_L3m_PAR_NRT
MODIST_L3m_PAR_NRT·v2022.0·dataset

Sunlight available for ocean plants, near real-time (Terra)

Terra MODIS Level-3 Global Mapped Photosynthetically Available Radiation (PAR) - Near Real-time (NRT) Data, version 2022.0
ocean NASA OB_CLOUD Level 3 active netCDF-4
In plain English

What it measures. Estimates of how much sunlight in the range plants use for photosynthesis reaches the ocean surface, mapped globally. It's basically the daily dose of usable light energy at the sea surface.

How it's made. Produced quickly (near real-time) from the MODIS sensor on NASA's Terra satellite, using best-available supporting weather and ozone data, so it favors speed over full calibration accuracy.

How & where you'd use it. Helps scientists estimate how much marine plant life (phytoplankton) can grow, interpret algae blooms, and feed ocean ecosystem models, with the near real-time version suited to timely monitoring.

What's measured

Oceans › Ocean Optics › Photosynthetically Active Radiation

Coverage & cadence

  • Time span2000-02-24 → ongoing
  • Measured byTerra (MODIS)
  • 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 Ocean Biology DAAC produces near real-time (NRT) products using the best-available combination of ancillary data from meteorological and ozone data. As such, the inputs and the calibration used are less than optimal. Near real-time products provide a snapshot of the data during a short time period within a single orbit. 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

modist_l3m_par_nrt_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="MODIST_L3m_PAR_NRT",
    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.