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questions about the framework, the data and the limits of both.
Last reviewed September 2026
CORDEX-MERIT is an interactive presentation of the multi-criteria GCM selection framework described in Ashfaq et al., A multi-criteria framework for CORDEX-CORE2 GCM selection. It is developed by Moetasim Ashfaq at Oak Ridge National Laboratory. The development of the framework was informed in part by feedback received through the CORDEX-CORE Task Force, particularly regarding the choice of evaluation metrics.
The framework is the method by which the driving models for CORDEX-CORE2 were selected, but it was not issued by WCRP or by CORDEX as a body. It is therefore not a WCRP standard binding on other downscaling activities, and nothing here should be read as an endorsement by WCRP, by CORDEX as a body, or by any of the modeling centers whose output it evaluates. Responsibility for the analysis and for its presentation rests with the authors.
A rank in this toolkit is the result of one defensible set of choices: a particular suite of 98 metrics, a particular way of weighting redundancy among them, and a particular rule for aggregating across regions and domains. The toolkit lets you vary those choices precisely so that their influence is visible. A model's position is a property of the framework as configured, not a verdict on the quality of the model or of the center that built it.
Two limits of scope are worth stating plainly, because they bear directly on how the results should be used. The criteria assess how well a global model represents the large-scale conditions a regional model inherits from it; they deliberately do not evaluate extremes, which coarse-resolution models represent poorly and which downscaling is intended to improve. A high rank therefore does not certify skill at reproducing observed extremes, and it is not a judgement of fitness for any particular impact application. Users whose application depends on extremes should apply their own screening to the downscaled output.
The framework is offered to inform expert judgement, not to replace it. It should not be the sole basis of a consequential decision.
The figures are computed from the archived data described below, and the toolkit is built so that what it displays can be traced back to that archive. Even so, no guarantee is given that the content is accurate, complete, current or uninterrupted. Values that could not be measured and were estimated instead are marked as such where they appear. The content, the interface and these terms may change without notice.
The data and analysis code are archived at 10.5281/zenodo.22760571 and carry the license stated in that deposit, which governs reuse. If you use the figures, the rankings or the derived data, please cite both the paper and the deposit.
The underlying CMIP6 model output and the ERA5 reanalysis are the work of the modeling centers and of ECMWF and Copernicus respectively, and remain subject to the terms of their own providers. Obtaining those terms is the user's responsibility.
Maps here show CORDEX domain outlines and IPCC AR6 reference regions over coastlines and national borders, drawn from public reference datasets and used only to locate the analysis. The boundaries, names and designations shown do not imply any opinion or endorsement concerning the legal status of any country, territory or area, or of its authorities, or concerning the delimitation of its frontiers.
Links to journals, repositories and data archives are offered for convenience. Those sites are not under our control, and no responsibility is taken for their content or availability. The synthesis figure can be drawn either by a renderer served from a third-party content delivery network or by the toolkit's own; the Privacy Policy explains what that choice means.
The toolkit is provided as is, without warranty of any kind, express or implied. To the extent permitted by law, no liability is accepted for any loss or damage arising from its use, from reliance on any result it presents, or from its unavailability.
You are welcome to use, share and build on what is here within the license of the archived deposit. Please do not present results from this toolkit as a WCRP standard or as guidance issued by CORDEX as a body, attribute them to the modeling centers, or reproduce them in a way that misrepresents the scope described above.
Questions about these terms, or about anything the toolkit shows: contact@cordex-merit.org
Last reviewed September 2026
CORDEX-MERIT asks for nothing about you. There is no account, no login, no cookie, no analytics and no third-party tracking of any kind. Nothing you select, filter, compare or download is sent to us or to anyone else.
The toolkit is a static site. The data files are served with the page and every figure is computed in your own browser, so the work happens on your machine rather than on a server that could observe it. Choosing a domain, moving a threshold, opening a metric or saving a figure produces no record anywhere but your own screen.
Your choice of light or dark theme is kept in your browser's local storage so the site does not forget it between visits. It stays on your device, is readable only by this site in your browser, and is never transmitted. Clearing your browser's site data removes it. Nothing else is stored.
The synthesis figure can be drawn two ways. Its default renderer is a
library loaded on demand from a public content delivery network at
cdn.plot.ly; making that request necessarily discloses your
IP address and browser details to the operator of that network, as any
web request does. The toolkit also has its own built-in renderer, and
selecting it means no request to that network is made. No other part of
the toolkit contacts a third party.
Links to journals, repositories and data archives only contact those sites if you choose to follow them, at which point their own privacy terms apply.
Whoever hosts this site may keep ordinary web server logs, which typically record IP addresses, requested files and timestamps for security and operational purposes. That collection is a function of the hosting arrangement rather than of the toolkit, and we do not use such logs to build profiles of visitors.
If you email the address below, we keep your message and address for as long as it takes to deal with what you raised, and for any related scientific correspondence. It is not added to a mailing list and is not shared, except where we are required to disclose it by law or by the policies governing our institution.
If this policy changes, the revised version will appear on this page with a new review date.
Questions about privacy, or a request concerning your correspondence with us: contact@cordex-merit.org