20 Years of Ensemble Prediction at ECMWF

Roberto Buizza


The first operational run of the ECMWF Ensemble Prediction System (EPS) was completed twenty years ago, on the 24th of November 1992. At that time, the EPS included a representation of initial uncertainties based on initial-time singular vectors, had 33 members and was run three-times a week at approximately a 200 km resolution with 19 vertical levels, for up to 10 days. Today, the system includes a more sophisticated simulations of initial perturbations based on singular vectors and an ensemble of data assimilations. Model uncertainties are also simulated using two stochastic schemes. Its size has been enlarged to 51 members. It is run twice a day for up to 15 days, coupled to a wave model, with a resolution of approximately 30 km up to forecast day 10 and 60 km afterwards. Twice a week the system is extended with a coupled dynamical ocean to 32 days. It includes a re-forecast suite used to compute the model climate and to generate calibrated forecast products such as the extreme forecast index. During this talk, the EPS development is reviewed, recent changes are presented and plans for future improvements are discussed