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Full catalog/MODISA_L3m_CHL
MODISA_L3m_CHL·v2022.0·dataset

Tiny ocean plants, chlorophyll levels (Aqua MODIS)

Aqua MODIS Level-3 Global Mapped Chlorophyll (CHL) Data, version 2022.0
ocean NASA OB_CLOUD Level 3 active netCDF-4
In plain English

What it measures. Global maps of chlorophyll-a in surface ocean water, which stands in for how much phytoplankton (tiny floating plant-like life) is present. Higher values mean more biological activity at the sea surface.

How it's made. Derived from the MODIS sensor on NASA's Aqua satellite and processed into gridded global composites of chlorophyll concentration.

How & where you'd use it. Used to study ocean ecosystems and fisheries, detect blooms and anomalies, and build time series of ocean health; readings in murky coastal or inland waters carry more uncertainty.

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 span2002-07-04 → ongoing
  • Measured byAqua (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 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

modisa_l3m_chl_access.py
import earthaccess
earthaccess.login(strategy="netrc")          # free Earthdata Login

results = earthaccess.search_data(
    short_name="MODISA_L3m_CHL",
    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.