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.
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.
The Quality Assurance Framework for Earth Observation consists of seven distinct key guidelines linked through an overarching document the QA4EO Principles. QA4EO activities and tasks are outlined in the QA4EO Implementation Plan.
Guideline QA4EO-QAEO-GEN-DQK-002 (A guide to content of a documentary procedure to meet the Quality Assurance requirements of GEO') is essentially the core requirement for QA4EO. If processes are carried out in full compliance of this fundamental guide, a user can have confidence in any resultant output. QA4EO-QAEO-GEN-DQK-002 provides the template to guide the user through the process, aided by the other six key guidelines for specific technical details, but in principle this guide provides all the information needed to be compliant.
In considering issues of interoperability and international harmonisation within any specific GEO community it is often helpful to start with a review of generic activities and from these define key requirements that drive the QA process. For example, in the space sector all derived information products originate from a measurement made by a satellite sensor. Thus, a set of key activities for every sensor could be defined for implementation during its development and operation.
Guideline QA4EO-QAEO-GEN-DQK-001 provides this satellite-based example to illustrate the process. This example shows how the top level requirements drive the need for community references, indicate critical generic deliverables for bias evaluation through comparisons and act as a starting point for more detailed technical procedures to underpin the top level requirements.
Official QA4EO Documentation
Practical guides to a metrological approach for EO
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.