Spatial and temporal characteristics of extreme rainfall: Added benefits with sub-kilometre-resolution climate model simulations?

Local, short-duration extreme precipitation events can cause floodings and have massive economic consequences. The climate change impact on such events is of great interest, but due to the small spatio-temporal scales involved, these are challenging to properly represent in climate models. This study analyses a new sub-kilometre (750 m) HARMONIE-Climate model simulation driven by ERA5 reanalysis data. Three convection-permitting models at 750 m, 3 and 5 km grid distance are analysed and compared with driving reanalyses, intermediate model simulations and a dense rain gauge network. The representation of convective events is analysed by a range of metrics categorised as spatial, temporal and event-focused. Precipitation events are analysed at both hourly and sub-hourly scales and a clear difference between model performance on these scales is found. Overall, we find a better performance for HCLIM750m for most metrics, yet the added benefits of the computationally intensive sub-kilometre scale simulation seems limited compared to the convection-permitting models at 3 and 5 km.