QA4EO is a best practice framework endorsed by The Group on Earth Observations (GEO) to establish The Global Earth Observation System of Systems — based on coordinated and harmonised processes and activities that enable interoperability. Its internationally agreed principles contain a suite of guidelines that provide a consistent approach across disciplines, including for fundamental data records (FDRs), thematic data products (TDPs), and fiducial reference measurements (FRMs).


It is critical that data and derived products are easily accessible in an open manner and have associated with them an indicator of quality traceable to reference standards (preferably SI) so users can assess suitability for their applications, i.e. the ‘fitness for purpose’.


A QI shall be based on documented and quantifiable assessments of evidence demonstrating the level of traceability to internationally agreed (where possible SI) reference standards.

Quality Indicators

A Quality Indicator (QI) shall provide sufficient information to allow all users to readily evaluate the fitness for purpose of Earth observation data or derived products.


Start here

This website provides tools, guides, templates, and rules for implementating QA4EO principles for demonstrating fitness for purpose of fundamental data records (FDRs), thematic data products (TDPs), and fiducial reference measurements (FRMs). This practical guidance is provided free-of-charge for practioners at all levels.


Learn about QA4EO and how to develop Earth observation data records based on QA4EO principles.

New users

Systematic guidance and training resources to empower new users to gain understanding of the principles of QA4EO.

"Data and derived products shall have associated with them an indicator of quality to enable users to assess their suitability for particular applications, i.e., their 'fitness for purpose'..."
The Quality Assurance Framework for Earth Observation (QA4EO) was established and endorsed by the Committee on Earth Observation Satellites (CEOS) to meet a requirement identified by the Group on Earth Observations (GEO) to enable interoperability and quality assessment of earth observation data.

This website and the metrological principles documents it hosts were developed in the frame of the Instrument Data Quality Evaluation and Assessment Service - Quality Assurance for Earth Observation (IDEAS-QA4EO) contract funded by ESA-ESRIN (n. 4000128960/19/I-NS), and builds on the work of previous projects, see Acknowledgements.

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