Lessons learnt on convection-permitting models and their uncertainty at both global and regional scale

The past 10 years of research proved that regional convection-permitting models (RCPMs) more realistically represent sub-daily statistics and extremes compared to GCMs and RCMs thanks to the possibility to switch off the parameterisation of convection at this resolution. Now, thanks to recent computational advancements, GCMs are approaching convection-permitting resolution (GCPM), but little is known on their performance at climatological scale over Europe.

Here we compare two 5-year GCPM simulations performed with IFS and ICON, respectively at 9 and 5km, within the NextGEMs project against the multi-model RCPM ensemble at circa 3 km run under the CORDEX Flagship Pilot project on Convective Phenomena over Europe and the Mediterranean (FPS Convection). The analysis focuses on the representation of sub-daily precipitation characteristics between GCPMs in comparison with the RCPM ensemble and several regional observational datasets over the greater Alpine region. In additional, the impact of a higher resolution (5km instead of 25km) of the ocean model is investigated thanks to an additional GCPM run. The natural variability of the GCPMs is evaluated with a bootstrapping approach and put in relation with the total and model uncertainty of the RCPM ensemble.  

Having GCMs that realistically represent the large-scale dynamics as well as the local scale process would be a crucial step forward and provide further confidence on the climate projections and support the Destination Earth project of the European Community.