Giovedì 9 Giugno alle ore 14:30 presso il Dipartimento di Ingegneria Civile, Ambientale e Meccanica dell’ Università di Trento (Aula 1P) si terrà il seminario: “Simulation of extreme European heatwaves with rare event algorithms in climate models“.
Il seminario, tenuto da Francesco Ragone (Università di Roma Tor Vergata, Royal Meteorological Institute of Belgium), potrà essere seguito anche in streaming:
Meeting ID: 831 0852 3508
Abstract The analysis of the dynamics and impacts of extreme events like heatwaves or floods, and the quantification of their probability, are major topics of interest in climate science. The analysis of extreme events however is hindered by the lack of statistics, due to the limited length of observational records, and to the huge computational costs required to run ensemble simulations with climate models with a number of ensemble members large enough to sample very rare events. This problem can be tackled using rare event algorithms, a family of computational techniques designed to guide an ensemble simulation to oversample target extreme events of interest. Here I will present an example of one such method, designed to study extreme events characterized by time persistence. I will show results obtained for extreme warm summers and heatwaves over France and Scandinavia with the climate model CESM in present day climate. The application of the algorithm concentrates the simulations on dynamical trajectories leading to persistently large regional surface temperature anomalies, shifting their probability distribution such that extreme warm summers and heatwaves become common. Thanks to this, we can estimate return times of extreme events several orders of magnitude larger than what is feasible with direct sampling, and we can show that extreme heatwaves in the model are associated with recurrent wavenumber 3 hemispheric teleconnection patterns. I will then discuss preliminary results on different applications and perspectives for future studies.