How many tiny ocean plants are in the sea (Sentinel-3B, reduced-res)

In plain English

What it measures. Global maps of chlorophyll-a in the surface ocean, a measure of how many microscopic plants (phytoplankton) are in the water, at a coarser, reduced resolution.

How it's made. Built from the OLCI ocean-color sensor on Europe's Sentinel-3B satellite, with measurements binned onto a global grid.

How & where you'd use it. Supports tracking ocean productivity, detecting blooms, and ecosystem and fisheries work. 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 span2018-04-25 → ongoing
Measured bySentinel-3B (OLCI)
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. This activity was informed by the Satellite Needs Working Group (SNWG), an interagency effort of the U.S. Government dedicated to identifying and addressing Earth observation needs across U.S. civilian federal agencies. Geophysical variables in this suite include: - chlor_a — Chlorophyll-a concentration (mg m⁻³)

Get the data

olcis3b_l3b_err_chl_access.py

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

results = earthaccess.search_data(
    short_name="OLCIS3B_L3b_ERR_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.

Official links

Earthdata Search allows users to search, discover, visualize, refine, and access NASA Earth Observation data. GET DATA
View the version history of this product. VIEW RELATED INFORMATION
NASA's Ocean Color Web - Data Distribution Site GET DATA
Sentinel-3B Homepage VIEW RELATED INFORMATION
OLCI Homepage VIEW RELATED INFORMATION
Satellite data procesing can be difficult. We're here to help! Visit the Oceandata Help Hub to navigate learning content for accessing visualizing, and analyzing data products. VIEW RELATED INFORMATION
Algorithm Theoretical Basis Document for Earth-observation Reduced Resolution (ERR) Chlorophyll (CHL) VIEW RELATED INFORMATION