Evaluation Of Extreme Precipitation Forecasts Using Convective-Permitting Modeling To Improve Streamflow Simulations In Tarapacá Region, Chile
Presenter: Lourdes Mendoza-Fierro1
Co-Author(s): Hsin-I Chang, Rodrigo Valdés-Pineda, Christoforus Bayu Risanto
Advisor(s): Dr. Christopher L. Castro
1Department of Hydrology and Atmospheric Sciences, University of Arizona
During the last decade, Tarapacá Region in northern Chile has experienced extreme precipitation events causing flash flooding and associated adverse socioeconomic impacts. Events likely to worsen in the future due to an increase of the intensity and frequency of convective storms driven by global warming. Recent studies have shown the ability to produce high precipitation forecast skill using convective permitting (CP) models over South America. Skill previously evaluated for weather events at continental and regional scales, that can later be used to evaluate and simulate short- and long-term hydrologic responses. In this research, all ensemble members from the Global Ensemble Forecast System (GEFS) are used to establish initial and lateral boundary conditions for extreme weather precipitation events, between 2012 and 2021, to initialize the Weather Research and Forecasting (WRF) model at a CP resolution in Tarapacá Region. Forecasts are done hourly to provide retrospective precipitation forecast 2 days prior, and 2 days after each observed weather event. Preliminary simulation results show significant improvement in total precipitation against the driving global forecast model and satellite observations. The CP-WRF climate simulations are used to improve streamflow simulations using a set of hydrologic models. Final combination of climate and hydrologic simulations is used to establish hybrid evaluation metrics for the development of comprehensive data assimilation assessments. This new hydroclimatic modelling paradigm will be operationally implemented in the Tarapacá Region to inform stakeholders and decision makers about the risk of having extreme convective storms that lead to destructive flash flooding events.