- How well do RCMs and ESDs reproduce the occurrence of extreme precipitation events over Southeastern South America?A case study approach.

BETTOLLI, MARIA LAURA; FEIJOO, MARTIN; BALMACEDA, ROCIO; DOYLE, MOIRA E.; OLMOS, MATIAS; POGGI, MERCEDES; SOLMAN, SILVINA; BLAZQUEZ, JOSEFINA; GONZALO DIAZ

Beijing

Conferencia; ICRC CORDEX - 2019; 2019

Individual extreme precipitation events over Southeastern South America (SESA) during the spring andsummer time are responsible of more than 40% of the total accumulated seasonal precipitation. Theseextreme events are associated with the occurrence of organized convection in the region. Given themesoscale features involved in their development, modelling their main features and lifecycles ischallenging. In this work we gather different modelling strategies, including several Empirical StatisticalDownscaling (ESD) models, several CORDEX Regional Climate Models (RCMs) for the South Americandomain at various horizontal resolutions and several convective permitting simulations performedwith the WRF model for selected case studies to assess the capability of different methodologies incapturing the spatial distribution of rainfall during the occurrence of an extreme event. The evaluationof different methodologies also allows identifying their capability in capturing (or not) the associatedphysical forcings triggering extreme events. Ten individual events were selected based on data fromthe TRMM dataset and the CPC-Unified gridded dataset for the period 1979-2015 satisfying thefollowing criteria: daily precipitation exceeding the 95th percentile and with a coverage of more than10% of grid points within SESA. Due to the large observational uncertainty, we also included severalobservational datasets to characterize the main features of the individual cases evaluated, whichinclude station data, gridded products (CPC-Unified data) and several precipitation estimates based onsatellite data (CHIRPS; MSWEP; TRMM; PERSIANN; CMOPRH). For each individual event, evaluationRCM simulations from the CORDEX database at 50 km and 25 km resolutions; 72-hours simulationsperformed with the WRF model driven by ERA-Interim reanalysis at roughly 20km, 12 km and 4 km,and several ESD models based on different techniques and different predictor variables werecompared.