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Full catalog/VIIRSJ2_L3b_CHL
VIIRSJ2_L3b_CHL·v2025.0·dataset

Tiny ocean plant abundance, chlorophyll (NOAA-21)

NOAA-21 VIIRS Level-3 Global Binned Chlorophyll (CHL) Data, version 2025.0
ocean NASA OB_CLOUD Level 3 active netCDF-4
In plain English

What it measures. Worldwide maps of chlorophyll-a concentration in surface seawater, a stand-in for how much phytoplankton (tiny floating ocean plants) is present.

How it's made. Made from VIIRS ocean-color observations on the NOAA-21 satellite, combined into gridded global composites.

How & where you'd use it. Used for tracking ocean productivity over time, spotting unusual blooms, supporting fisheries and ecosystem work, and teaching. Readings near murky coastal or inland waters are less certain.

What's measured

Oceans › Ocean Optics › Chlorophyll › Chlorophyll ConcentrationBIOSPHERE › VEGETATION › CHLOROPHYLLOCEANS › OCEAN CHEMISTRY › CHLOROPHYLLOCEANS › OCEAN CHEMISTRY › PIGMENTS › CHLOROPHYLLTERRESTRIAL HYDROSPHERE › WATER QUALITY/WATER CHEMISTRY › WATER CHARACTERISTICS › CHLOROPHYLL CONCENTRATIONSBIOSPHERE › ECOSYSTEMS › AQUATIC ECOSYSTEMS › PLANKTON › PHYTOPLANKTON

Coverage & cadence

  • Time span2022-11-10 → ongoing
  • Measured byNOAA-21 (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 Chlorophyll-a data suite provides global, gridded composites of surface chlorophyll-a concentration (a proxy for phytoplankton biomass). CHL supports time-series and climatologies, anomaly detection, ecosystem and fisheries applications, and teaching/training, and pairs well with AVW, PAR, Kd(490), SST, and winds for environmental context. Note: retrievals in optically complex coastal/inland waters may carry higher uncertainty—refer to the mission/algorithm documentation (e.g., OCx/OCI) for details. Geophysical variables in this suite include: - chlor_a — Chlorophyll-a concentration (mg m⁻³)

Get the data

viirsj2_l3b_chl_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="VIIRSJ2_L3b_CHL",
    version="2025.0",
    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.