Assessing Regional Climate Models (RCMs) Ensemble-Driven Reference Evapotranspiration over Spain

The present work applies a novel methodology of combining multiple Regional Climate Models (RCMs) (or ensemble) that are based on the seasonal and annual variability of temperatures over Spain, which allows for the quantification and reduction of uncertainty in the projections of temperature based-potential evapotranspiration. Reference evapotranspiration (ETo) is one of the most important variables in water budgets. Therefore, the uncertainties in the identification of reliable trends of reference evapotranspiration should be taken into account for water planning and hydrological modeling under climate change scenarios. From the results over Spain, the RCMs ensemble reproduces well the yearly and seasonal temperature observed dataset for the time reference period 1961-1990. An increase in the ensemble-driven ETo for time period 2021-2050 over Spain is expected, which is motivated by an increase in maximum and minimum temperature, with the consequent negative impacts on water availability.