Extreme precipitation events during dry years as depicted by the set of FPS-SESA convection-permitting simulations

BETTOLLI MARIA LAURA; DA ROCHA, R.P.; SOLMAN, S.; MILOVAC J.; FERNANDEZ, JESUS; COPPOLA, E; RAFFAELE, F; BLAZQUEZ, J; PREIN, A; OLMO, MATIAS; BALMACEDA HUARTE, R

Bergen

Workshop; VII Convection Permitting Climate Modelling Workshop; 2023

NCAR-Universidad de Bergen

Extreme daily precipitation events in Southeastern South America (SESA) dominate the contribution to the hydrological cycle, having large impacts on the different productive systems over this highly populated area. Since 2018, SESA has been experiencing unprecedented dry conditions that, combined with high temperatures, have led to widespread crop failures, wildfires and reduced water availability. Although the recent years were characterized by these particularly dry conditions, many extreme and localized precipitation events occurred over SESA.In the second phase of the Coordinated Regional Downscaling Experiment (CORDEX) Flagship Pilot Study (FPS) over SESA (FPS-SESA) a targeted kilometer-scale climate modeling experiment was designed covering 3 consecutive years from June 2018 to May 2021 to study extreme precipitation events during this exceptional dry period. Different RCMs and institutions contributed to this experiment with 5 simulations, 2 of them based on WRF (University of Cantabria and NCAR South America Affinity Group) and 3 based on RegCM5 (University of Sao Paulo and ICTP).This study analyzes extreme precipitation events during dry conditions over SESA as depicted by this set of convection-permitting simulations (CPRCMs). To this end, different temporal and spatial aspects of daily extreme precipitation (location, intensity, sequence and spatial coverage) are evaluated together with the dominant dry conditions and the occurrence of dry spells, using ERA5 and different observational datasets as reference. The inter-comparison of wet and dry events varied across SESA -depending on the aspect analyzed- showing some differences among observational datasets and CPRCMs. Extreme daily precipitation tends to occur in sectorized areas of SESA conditioned by dominant circulation structures. CPRCMs were able to successfully reproduce these features associated with extreme precipitation frequencies, but exhibit some spread in their location and intensity.