Cyclones are essential elements of the climate system and water cycle but also major natural hazards in the densely populated Mediterranean basin. In the framework of the COST Action "European network for Mediterranean cyclones in weather and climate - MedCyclones", a model intercomparison project investigates the dynamics and predictability of case studies using modelling setups that are not yet available to operational forecasting systems. The intercomparison involves 10 sets of simulations based on 5 mesoscale models and multiple combinations of physical parameterizations. All sets include the same sensitivity simulations to initial and lateral boundary conditions and horizontal resolution. Here we focus on tropical-like cyclone (Medicane) Ianos that hit Greece in mid September 2020 and was poorly predicted by operational forecasts. Models systematically perform better when initialized from operational IFS analysis data compared to the widely used ERA5 reanalysis. Reducing horizontal grid spacing from 10 km (convection-parameterized) to 2 km (convection-permitting) further improves the cyclone track and intensity. This highlights the critical organization of convection during the early cyclogenesis for the phasing with an upper-level jet. Higher resolution enhances convective activity and favorably preconditions the jet, which controls the subsequent cyclone intensification and evolution.The 10 sets of simulations show robust agreement but also reveal model specificities such as the possible need for a convective parameterization even at 2 km horizontal grid spacing. While they require generalization to other cases of Mediterranean cyclones, the results shall provide guidance for the next generation of global convection-permitting models in weather and climate.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)