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Description

The Inherent Optical Properties (IOP) suite provides per-pixel inherent optical properties - quantities that describe how seawater and its constituents absorb and scatter light, independent of illumination or viewing geometry. IOPs are retrieved from spectral Remote Sensing Reflectance (Rrs) using the default configuration of the Generalized Inherent Optical Properties (GIOP) model framework. These products support water-type classification, water-clarity assessment, biogeochemical studies, and forward/adjoint radiative-transfer applications, and they enable more robust cross-sensor comparisons than purely apparent (AOP) products.

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:
?~@? a ?~@~T Total absorption coefficient (sum of pure water + phytoplankton + CDOM/detritus, m?~A?¹)
?~@? bb ?~@~T Total backscattering coefficient (m?~A?¹)

?~@? aph_443 ?~@~T Phytoplankton absorption coefficient at 443 nm (m?~A?¹)
?~@? aph_unc_443 ?~@~T Uncertainty in absorption due to phytoplankton at 443 nm (m?~A?¹)
?~@? adg_443 ?~@~T Combined CDOM + non-algal detritus absorption coefficient at 443nm; accompanied by adg_s (spectral slope, units nm?~A?¹).
?~@? adg_unc_443 ?~@~T Uncertainty in absorption due to gelbstoff and detrital material at 443 nm (m?~A?¹).
?~@? bbp_443 ?~@~T Particulate backscattering coefficient at 443nm (m?~A?¹); include bbp_s (power-law slope, unitless) describing spectral shape.
?~@? bbp_unc_443 ?~@~T Uncertainty in particulate backscattering at 443 nm (m?~A?¹).
?~@? rrsdiff ?~@~T Fractional mean Rrs difference.

Product Summary

Platforms
Sentinel-3A
Instruments
OLCI
Spatial Extent

N: 90 S: -90 E: 180 W: -180

Location
GLOBAL OCEAN
Coordinate System
CARTESIAN
Granule Spatial Representation
CARTESIAN
Temporal Extent
2016-04-05 to Present
Data Partner
Ocean Biology Processing Group (OBPG) ,
Ocean Biology Distributed Active Archive Center (OB.DAAC), Global Change Data Center, Earth Sciences Division, Science and Exploration Directorate, Goddard Space Flight Center, NASA (NASA/GSFC/SED/ESD/GCDC/OB.DAAC)
Concept ID
C3406447204-OB_CLOUD
Data State
ACTIVE
Number of Files/Granules
225840
Processing Level
3
Published
Updated
Science Keywords
Absorption ,
Scattering ,
Gelbstoff ,
Phytoplankton

Citation

Citation is critically important for dataset documentation and discovery. This dataset is openly shared, without restriction, in accordance with the EOSDIS Data Use and Citation Guidance.

Copy Citation

NASA Ocean Biology Processing Group. (2025). Sentinel-3A OLCI Level-3 Global Mapped Earth-observation Reduced-Resolution (ERR) Inherent Optical Properties (IOP) Data, version 2022.0 [Data set]. NASA Ocean Biology Distributed Active Archive Center. https://doi.org/10.5067/S3A/OLCI/L3M/ERR/IOP/2022.0 Date Accessed: 2026-03-07

Documents

Variables

The table below lists the variables contained within a single granule for this dataset. Variables often contain observed or derived geophysical measurements collected from a variety of sources, including remote sensing instruments on satellite and airborne platforms, field campaigns, in situ measurements, and model outputs. The terms variable, parameter, scientific data set, layer, and band have been used across NASA’s Earth science disciplines; however, variable is the designated nomenclature in NASA’s Common Metadata Repository (CMR). Variable metadata attributes such as Name, Description, Units, Data Type, Fill Value, Valid Range, and Scale Factor allow users to efficiently process and analyze the data. The full range of attributes may not be applicable to all variables. Additional information on variable attributes is typically available in the data, user guide, and/or other product documentation.

For questions on a specific variable, please use the Earthdata Forum.

Name Description Units Data Type Fill Value Valid Range Scale Factor
adg_443 Absorption due to gelbstoff and detrital material at 443 nm, GIOP model m^-1 int16 -32767 -30000 to 25000 9.9999997473788E-5
adg_s detrital and gelbstoff absorption spectral parameter for GIOP model m^-1 nm^-1 float32 -32767 0 to 5 N/A
adg_unc_443 Uncertainty in absorption due to gelbstoff and detrital material at 443 nm, GIOP model m^-1 int16 -32767 -24998 to 25000 9.9999997473788E-5
aph_443 Absorption due to phytoplankton at 443 nm, GIOP model m^-1 int16 -32767 -24998 to 25000 9.9999997473788E-5
aph_unc_443 Uncertainty in absorption due to phytoplankton at 443 nm, GIOP model m^-1 int16 -32767 -24998 to 25000 9.9999997473788E-5
a_400 Total absorption at 400 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_412 Total absorption at 412 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_443 Total absorption at 443 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_490 Total absorption at 490 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_510 Total absorption at 510 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_560 Total absorption at 560 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_620 Total absorption at 620 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
a_665 Total absorption at 665 nm m^-1 int16 -32767 -24998 to 32000 9.9999997473788E-5
bbp_443 Particulate backscattering at 443 nm, GIOP model m^-1 int16 -32767 -27999 to 1999 4.9999998736894E-6
bbp_s backscattering spectral parameter for GIOP model m^-1 nm^-1 float32 -32767 -3 to 3 N/A
bbp_unc_443 Uncertainty in particulate backscatter at 443 nm, GIOP model m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_400 Total backscattering at 400 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_412 Total backscattering at 412 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_443 Total backscattering at 443 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_490 Total backscattering at 490 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_510 Total backscattering at 510 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_560 Total backscattering at 560 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_620 Total backscattering at 620 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
bb_665 Total backscattering at 665 nm m^-1 int16 -32767 -27999 to 31999 4.9999998736894E-6
lat Latitude degrees_north float32 -999 -90 to 90 N/A
lon Longitude degrees_east float32 -999 -180 to 180 N/A
palette palette N/A uint8 N/A N/A N/A
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