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Collocation Session 3: Validation processes in ECV products. CORE-CLIMAX Collocation REA Brussels, 15-16 May 2013 Jean-Christophe Calvet, Meteo-France. Definition(s) of validation (adapted from wikipedia).
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Collocation Session 3:Validation processesin ECV products CORE-CLIMAX Collocation REA Brussels, 15-16 May 2013 Jean-Christophe Calvet, Meteo-France
Definition(s) of validation (adapted from wikipedia) • Verification and Validation: independent procedures used together for checking that a product, service, or system meets requirements and specifications and that it fulfils its intended purpose. • Validation: "Are you building the right thing?" Assurance that the users’ needs (e.g. accuracy) are met. Involves requirement analysis, prototyping, tests and acceptance by external end users. • Verification: "Are you building it right?" Evaluation of whether or not pre-defined specifications are satisfied. It is often an internal process. • Both should be performed by disinterested third party and both are needed throughout the production lifecycle.
Earth Observation • Validation: independent assessment of the quality • Direct validation: based on independent (e.g. in situ) data • Indirect validation: comparison with other pre-existing products • Scientific validation: results are published e.g. in the open peer-reviewed literature using standard methods/scores Slide 3
International initiatives • CEOS Working Group on Calibration and Validation • Includes a Land Product Validation (LPV) subgroup • GEO-QA4EO: specification of quality indicators within EO products (standardization effort) • Europe: • ESA: CAL/VAL activities, ESA-CCI • EUMETSAT: Satellite Application Facilities (SAF) • GMES-Copernicus: • FP7 projects • GIO-GlobalLand Slide 4
Specific ECV requirements • Long time series • Direct validation is limited in space and time • Indirect validation • product intercomparison • comparison with models • integration into models (data assimilation / reanalyses) Slide 5
Motivates Core-ClimaxKey Objective #3 “Propose a validation process aiming at qualifying the accuracy of the climate variables” • Coordinate with existing international initiatives • Synergies in methods used for ocean/atmosphere/land • Synergies of EO with model simulations and in situ observations
Date of lowest SSM value in 2009 Model ASCAT Corrected ASCAT DoY Example: soil moisture Seasonal corrections of ASCAT SSM Barbu et al. 2013
Discussion Points • Outcome of the various projects • Lessons learnt: recommendation on best practices ? • Quality indicators ? • Product continuity and consistency ? • Who did/should do the assessment ? • Is a generic approach possible ? • Cross-cutting quality monitoring: • Data assimilation ? • Most obvious users of ECV products: reanalyses groups, climate modellers,… • How to get feedback from more downstream application users ? • e.g. (over land) food security, drought monitoring, …