Antje Weisheimer, Paco Doblas-Reyes, Tim Palmer, Tim Stockdale - European Centre for Medium-Range Weather Forecasts (ECMWF) Reading, UK
In the EU-funded project DEMETER (Development of a European Multimodel Ensemble system for seasonal to inTERannual predictions; Palmer et al., 2004) a comprehensive set of multi-model coupled atmosphere-ocean seasonal hindcasts for the period 1958-2001 had been generated. Within the project the multi-model ensemble predictions were evaluated extensively using a variety of both deterministic and probabilistic skill scores. It had been demonstrated that the multi-model ensemble of seven state-of-the-art coupled GCMs leads, on average, to more consistent and reliable forecasts than those based on single-model ensembles. Please see the DEMETER website for more information on the project.
ENSEMBLES (ENSEMBLE-based Predictions of Climate Change and their ImpactS) is an ongoing European Integrated Project, which builds on the experience of DEMETER. Its intention is to produce an objective probabilistic estimate of uncertainty in future climate at the seasonal to decadal and longer timescales. One of the main questions on the seasonal, interannual and decadal time scales is the assessment of the relative benefits and merits of producing ensemble forecasts using multiple models, stochastic parameterisations of physical processes or perturbed physical parameters as different approaches to include model uncertainty. For more information see the ENSEMBLES project's final report.
For this project we propose to perform a comparison of the multi-model performance of the DEMETER and ENSEMBLES seasonal-to-interannual ensemble forecasts with the SMIP seasonal multi-model. As both the DEMETER and ENSEMBLES multi-models consist of coupled models developed in Europe, it is likely that additional models developed elsewhere may add to the skill and improve the quality of the forecasts. It is thus proposed to evaluate the performance of a grand multi-model ensemble covering all available coupled models from the three projects with respect to the already existing multi-model ensembles. Furthermore, a comparison of the grand multi-model ensemble forecasts with those produced by different methods (stochastic physics and perturbed parameters) will be planned.
References
- Palmer, T.N., A. Alessandri, U. Andersen, P. Cantelaube, M. Davey, P. Délécluse, M. Déqué, E. Díez, F.J. Doblas-Reyes, H. Feddersen, R. Graham, S. Gualdi, J.-F. Guérémy, R. Hagedorn, M. Hoshen, N. Keenlyside, M. Latif, A. Lazar, E. Maisonnave, V. Marletto, A. P. Morse, B. Orfila, P. Rogel, J.-M. Terres, M. C. Thomson, 2004. Development of a European multi-model ensemble system for seasonal to inter-annual prediction (DEMETER). Bull. Amer. Meteorol. Soc., 85, 853-872.