Seasonal Hydrometeorological Ensemble Prediction System; Forecast of Irrigation Potentials in Denmark

Abstract:

The European Center for Medium Weather Forecast seasonal ensemble prediction system (ECMWF-SEPS) of weather variables such as precipitation, temperature and evapotranspiration is used as input to an integrated surface-subsurface hydrological model based on the MIKE SHE system to generate probabilistic forecasts of the irrigation requirements in the Skjern river catchment in Denmark. We demonstrate the usability of the ECMWF-SEPS and discuss the challenges and areas of opportunities when issuing forecasts generated with this methodology.

A simple bias-correction and downscaling technique, namely linear scaling, is applied to the raw inputs to remove the bias intrinsic in ensemble prediction systems and to downscale the data to a scale appropriate for hydrological modelling. The forecasts of the meteorological variables are analysed for accuracy and reliability by comparing them to meteorological observations. Additionally, weather ensembles will be generated using the nearest-neighbour resampling technique with the purpose of exploring additional possibilities of hydrometeorological system input for complementing situations where the SEPS is lacking skill.