EURO-CORDEX CMIP6 GCM Selection & Ensemble Design: Best Practices and Recommendations

This white paper and the accompanying tables published in GitHub are meant to help modellers in EURO-CORDEX, and elsewhere, make informed decisions when it comes to selecting GCMs for downscaling from the CMIP6 archive. While the approach to GCM selection during the CMIP5 downscaling phase cannot be wholly considered an “ensemble of opportunity” it is also true that the selection of GCMs was not as rigorous as it could have been. We aim to improve upon this situation and help us construct smarter, more reliable and more useful downscaled ensembles (dynamical, statistical and hybrid) and make the selection process more transparent. The community should consider this a living document that will evolve along with our scientific understanding. We rely mostly on peer-reviewed literature for the assessment of CMIP6 models provided in the linked tables and have devised innovative ways to include relevant metadata and update the tool with new results [https://wcrp-cordex.github.io/cmip6-for-cordex]. We encourage the wider CORDEX community to become active in this activity, suggest ways to improve and alert us when new results become available or mistakes are noted in the evaluation tables. We also hope that this EURO-CORDEX GCM selection work can inspire good practices and contribute to fruitful discussions in other CORDEX domains and CORDEX-FPS activities.