Raw color and light measured over Earth (Sentinel-3A)
What it measures. This captures the raw color and brightness of sunlight reflected from Earth in 21 bands of visible and near-infrared light, at about 300 m detail across land and ocean. It records how much light reaches the satellite before any atmospheric correction.
How it's made. It comes from the OLCI imaging spectrometer on Europe's Sentinel-3A satellite; the raw radiances are calibrated, georeferenced, and resampled onto an even grid.
How & where you'd use it. This is an early-stage input product. Scientists use it to build higher-level products on ocean color, vegetation, and land surfaces rather than reading it directly.
What's measured
Coverage & cadence
- Time span2016-04-25 → ongoing
- Measured bySentinel-3A (OLCI)
- Processing levelLevel 1B
- Spatial extent-180, -90, 180, 90
- FormatsnetCDF-4
- StatusACTIVE
What you can do with it
- Track deforestation, fire scars and land-cover change
- Monitor crop and vegetation health (NDVI/EVI)
- Map how built-up vs. green an area is over time
Official description
The OLCI/Sentinel-3A L1 Full Resolution Top of Atmosphere Reflectance product, S3A_OL_1_EFR is generated from the data aquired by the Ocean and Land Colour Instrument (OLCI) on board European Earth Observation satellite mission, SENTINEL-3. The OLCI is a push-broom imaging spectrometer that measures solar radiation reflected by the Earth at a ground spatial resolution of around 300m, over all surfaces, in 21 spectral bands. OLCI is based on the imaging design of ENVISAT's Medium Resolution Imaging Spectrometer (MERIS). It has a 1270km wide swath. For more information about the instrument and the mission, visit [Sentinel Online](https://sentinel.esa.int/web/sentinel/home). The S3A_OL_1_EFR is a Level-1B product. This is composed of an information package map, called a manifest, 22 measurement data files, and seven annotation data files. The 21 measurement data files (one for each band) consist of Top Of Atmosphere (TOA) radiances, calibrated to geophysical units (W.m-2. sr-1 Micro meter-1), georeferenced onto the Earth's surface, and spatially resampled onto an evenly spaced grid. Seven annotation files provide information on illumination and observation geometry, environment data (meteorological data) and quality and classification flags. Both measurement data files and annotation data files are written in netCDF 4 format. The manifest file is in XML format and contains metadata associated with the instrument and the processing. The S3A_OL_1_EFR is generated in Earth Observation (EO) processing mode and all parameters in this product are provided for each re-gridded pixel on the product image and for each removed pixel. The OL_1_EFR product package is described below: Element name Description Manifest.safe SENTINEL-SAFE product manifest Oa##_radiance.nc Radiance for OLCI acquisition bands 01 to 21 Removed_pixels.nc Removed pixels information needed for Level-1C generation Time_coordinates.nc Time stamp annotations Geo_coordinates.nc High resolution georeferencing data Quality_flags.nc Classification and quality flags Tie_geo_coordinates.nc Low resolution georeferencing data Tie_geometries.nc Sun and view angles Tie_meteo.nc ECMWF meteorology data Instrument_data.nc Instrument data note: Oa## represents all the OLCI channels (Oa1 to Oa21). For more information about the product, read the SENTINEL-3 OLCI [User Guide](https://sentinel.esa.int/web/sentinel/user-guides/sentinel-3-olci).
Get the data
import earthaccess
earthaccess.login(strategy="netrc") # free Earthdata Login
results = earthaccess.search_data(
short_name="S3A_OL_1_EFR",
version="1",
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 LAADSBrowsing CMR needs no login. Downloading or streaming bytes needs a free Earthdata Login + the earthaccess package.