Impact of the horizontal resolution on precipitation in an ensemble of regional climate models from the FPS URB-RCC

The WCRP CORDEX “Flagship Pilot Study URBan environments and Regional Climate Change” (FPS URB-RCC) aims to understand the interactions between urban areas and regional climate change. As part of the STAGE-0 Test simulations, which focus on double-nested downscaling of two short weather events for the region of Paris, France, this study discusses the impact of the horizontal resolution on daily precipitation during the whole period of simulation (4-5 months). The simulations are driven by ERA5.1 reanalysis data and two different resolutions are taken into account: ~ 12 and 3 km, the first covering Europe (EUR-12; PARIS-12) and the second centered over Paris (PARIS-3); in total, 23 and 29 simulations are considered for the analysis, respectively. Preliminary results were compared to EOBS data and show that basically all models were able to capture the precipitation over the city of Paris that occurred in May 2020. The PARIS-3 simulations showed some improvement in representing the averaged precipitation over the city, as well as the minimum and maximum values observed inside the domain of the city. Nevertheless, five days before the event, both resolutions overestimated a short precipitation event (by 200%), although capturing the timing. Further investigation regarding the associated synoptic condition simulated by the models in both resolutions will be explored with the aim of understanding the dynamics related to the events.