CONICET | Buscador de Institutos y Recursos Humanos

The development and evaluation of an ensemble hindcasting and forecasting system (EHS and EFS, respectively) for storm surges at the Río de la Plata Estuary (RdP) is presented. The models were forced by atmospheric sea level pressure and 10‐m winds. The ensemble forcing for the EHS was generated by temporal‐spatial shifting of the operational glocontrol ERA5 reanalysis provided by the European Centre of Medium‐Range Weather Forecast (ECMWF), because de ERA5 associated ensemble shows too little dispersion in this area. EFS, instead, was based on a lead time of 4 days and forced with the 50‐member high resolution ensemble prediction systems of the ECMWF. EHS was evaluated for a long period comprising the 2000‐2010 decade, whereas EFS was evaluated for the ten most extreme surges that occurred during that period: five positive (that cause coastal flooding) and five negative (that affect navigation and drinking water supply) events. Based on traditional statistics (area under the ROC curve and Brier scores) both systems were assessed from a probabilistic point of view. Results show that both EHS and EFS can incorporate more than 90% of the observations in the uncertainty range. They also presented good skill in hindcasting and forecasting surges and particularly extreme events, being EHS about 20% better thacontrol model and EFS up to 55% better, in agreement with state‐of‐the‐art models developed for other parts of the world. Results also showed that EFS can guess with a 95% of confidence the most of the surge peaks with a range of uncertainty of about ±0.90 m and ±9 h. Therefore, results encourage the implementation of EHS and EFS as a useful and robust tool for future climate studies, decision makers and the general public, improving the quality of risk management decisions by quantifying the forecast uncertainty.