The QA4EO best practice framework was endorsed by the Group on Earth Observations (GEO) to establish a Global Earth Observation System of Systems — based on coordinated and harmonised processes and activities that enable interoperability and and quality assessments of earth observation data. Its guidelines provide consistency across disciplines, including for fundamental data records (FDRs), thematic data products (TDPs), and fiducial reference measurements (FRMs).
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About QA4EO
Projects
Acknowledgement: since the endorsement of QA4EO, several collaborations between metrologists and the Earth Observation community developed detailed examples of how these principles can be applied in practice.
IDEAS-QA4EO
IDEAS-QA4EO is the IDEAS+ follow-on contract started in Nov 2019; it shares the same principles and objectives of IDEAS+ with reinforced focus on R&D and Metrology.
Projects that contributed to development of QA4EO framework concepts
FIDUCEO
FIDUCEO – Fidelity and uncertainty in climate data records from Earth Observations — was a H2020 project led by Reading University, that established metrological techniques for determining traceability and uncertainty information in long-term historical data records (fundamental climate data records) from which climate data records of ECVs are calculated.
GAIA-CLIM
The H2020 GAIA-CLIM project (2015 - 2018) aimed established sound methods for the characterisation of satellite-based Earth Observation (EO) data by surface-based and sub-orbital measurements (non-satellite measurements).
MetEOC
Four EMPIR MetEOC projects, led by NPL, establish metrological techniques for Earth Observation, including pre-flight calibration, post-launch on-board and vicarious calibration and the validation of higher-level products.
UK NMS
The National Measurement System (NMS) provides the UK with an infrastructure of laboratories that deliver world-class measurement science and technology and provide traceable and increasingly accurate standards of measurement.
Projects that applied concepts to FRMs
RadCalNet (ACTION series)
RadCalNet is an initiative of the Working Group on Calibration and Validation of the Committee on Earth Observation Satellites. The RadCalNet service provides satellite operators with SI-traceable Top-of-Atmosphere (TOA) spectrally-resolved reflectances to aid in the post-launch radiometric calibration and validation of optical imaging sensor data. The ACTION / ACTION-2 / ACTION-3 projects for the ESA-ESTEC supported CEOS to maintain and further develop the RadCalNet service provision of SI-traceable Top-of-Atmosphere (TOA) spectrally-resolved reflectances to satellite operators.
FRM4Fire
Fiducial Reference Measurements for Fire (FRM4FIRE) — developing field measurement protocols for validating earth observation-based fire products. The project team is applying airborne data collected in a field campaign in September 2024 over Canada to compile uncertainty information will support confidence in Sentinel-3 fire observations.
FRM4SOC
FRM4SOC — Fiducial Reference Measurements for Satellite Ocean Colour — with funding from ESA, was structured to provide support for evaluating and improving the state of the art in ocean colour validation through a series of comparisons under the auspices of the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration & Validation and in support of the CEOS ocean colour virtual constellation.
FRM4VEG
FRM4VEG – Fiducial Reference Measurements for Vegetation — is a European Space Agency (ESA) managed project focused on establishing the protocols required for traceable in-situ measurements of vegetation-related parameters, to support the validation of Copernicus products from Sentinel-2, -3, and PROBA-V.
FRM4STS
FRM4STS established and maintained SI traceability of global Fiducial Reference Measurements (FRM) for satellite derived surface temperature product validation.
St3TART
St3TART — Sentinel-3 Topography mission Assessment through Reference Techniques — is an 18-month project funded by the EU and ESA, and led by NOVELTIS with a consortium of 17 partners. The project aims to generalize the concept of FRM for the Copernicus Sentinel-3 Surface Topography Mission (STM) and to collect and distribute FRM data for the validation of the satellite mission over inland waters, sea ice and land ice.
Projects that applied concepts to FDRs and TDPs
FDR4ALT
FDR4ALT with funding from ESA was structured to provide support for evaluating and improving the state of the art in ocean colour validation through a series of comparisons under the auspices of the Committee on Earth Observation Satellites (CEOS) Working Group on Calibration & Validation and in support of the CEOS ocean colour virtual constellation.
FDR4ATMOS
The Fundamental Data Record for ATMOSpheric Composition (FDR4ATMOS) project is part of the ESA Long Term Data Preservation (LTDP) programme. The main objective of the FDR4ATMOS project is to develop a cross-instrument Level 1 product for GOME-1 and SCIAMACHY (phase 1) and to add GOME-2 data (phase 2)
ASELSU
ASELSU — ASSESSMENT SEA LEVEL RISE STABILITY UNCERTAINTY - EXPRO+ — studies feasibility of the Sentinel-6 Next Generation space component to address new requirements by a full assessment of the Sentinel-6 Sea Level Rise Uncertainty Stability Budget using metrological best practices and procedures.
C3S 311c Lot 1 satellite data rescue
C3S 311c Lot 1: Satellite Data Rescue — Reading and NPL led project to rescue satellite data from the 1960s through the 1970s (multiple sensors) plus data from the SSU sensor (1980s-2000s). Provides quality assessments and improvements with an assessment of the data with a bias adjustment model.
Quality Control/Assessment projects
QA4ECV
QA4ECV was initiated in 2014 to demonstrate how reliable and traceable quality information can be provided for satellite and ground-based measurements of climate and air quality parameters. The project developed and applied a Quality Assurance framework on new and improved multi-decadal data records of the Land ECVs Albedo, Leaf Area Index (LAI), and Fraction of Absorbed Photosynthetically Active Radiation (FAPAR), and of the Atmosphere ECVs nitrogen dioxide (NO2), formaldehyde (HCHO), and carbon monoxide (CO).
C3S_51_Lot 2_NPL
C3S_51_Lot 2_NPL — Evaluation and Quality Control for observational datasets within the C3S climate data store. Set a framework for the evaluation and quality control assessment of observations to be included in the C3S climate data store.
C3S2_521
C3S2_521 (2025 – 2028)– Evaluation and Quality Control for Applications, Indicators and Derived Datasets.
EDAP
EDAP — The Earthnet Data Assessment Pilot (EDAP) — is a project assessing the quality and suitability of candidate missions being considered for the Earthnet Third Party Missions (TPM).
QA4EO Best Practice
QA4EO encompasses a framework and set of ten best-practice guidelines, with example templates to support consistent implementations with credible evidence of compliance, thereby allowing data product users to assess adequacy and 'fitness for purpose' of datasets.
QA4EO-compliant processes unequivocally assure data quality and encourage harmonisation across the whole GEO community, providing an internationally coordinated operational framework to facilitate interoperability and harmonisation. Although the QA4EO guidelines were originally developed to meet the needs of the space community, they have been written with the aid of national metrology institutes of the UK and the USA and, where appropriate, are based on the best practices of the wider non-EO community. The processes are readily adoptable by all GEO communities as a top-level framework that can be translated and implemented to serve specialist needs.
QA4EO is driven by the key principle that all measurements/processes must have associated quality indicators (QIs) based on documented evidence of traceability to reference standards agreed by the scientific community.
QA4EO, therefore, requires the establishment of an unbroken chain of uncertainty evaluation from the platform and onboard payload elements to the final product processing steps, integrating the supportive ground-based activities.
Case studies
The following case studies show examples of QA4EO compliant methodologies or ideas applied in practice, where each directly followed or independently implemented QA4EO methodologies.
Levels of technical detail within each case ranges from level 3 (examples of implementations of QA4EO in a particular field), to level 1 case studies that provide more concise descriptions.
NOAA Maturity Matrix for CDRs
Intercomparison of remote sensing derived fAPAR datasets
WELD: Web - Enabled Landsat Data
RAdiative transfer Model Intercomparison (RAMI)
GSICS Procedure for Product Acceptance (GPPA)
Quality Assurance Framework for Earth Observation (QA4EO) was established and endorsed by the Committee on Earth Observation Satellites (CEOS) to serve a requirement identified by the Group on Earth Observations (GEO) to enable interoperability and quality assessments of Earth observation data.This website and hosted metrological principles documents 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 work of previous projects, see About QA4EO.
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