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BSTRACT A new and consistent convection scheme, providing continuous treatment of this atmospheric process, is described. The main concept ensuring the consistency of the whole system is buoyancy, a key element of any convective vertical motion. The buoyancy constitutes the forcing term of the convective vertical velocity, which is then used to define the triggering condition, the mass flux and the rates of entrainment-detrainment. The buoyancy is also used in its vertically integrated form to express the closure condition as a CAPE relaxation. The continuous treatment of convection from dry thermals to deep precipitating cumulus is made possible through the use of a continuous formulation of the entrainment-detrainment rates and CAPE relaxation time, together with an embedded precipitation scheme. This convection scheme is first evaluated with the help of single-column model simulations of specific case studies encompassing a variety of convective situations. Second, a coupled general-circulation model multiyear simulation is provided as a means to assess the model climate with respect to observations. [ABSTRACT FROM AUTHOR]

A multi-model ensemble-based system for seasonal-to-interannual prediction has been developed in a joint European project known as DEMETER (Development of a European Multimodel Ensemble Prediction System for Seasonal to Interannual Prediction). The DEMETER system comprises seven global atmosphere–ocean coupled models, each running from an ensemble of initial conditions. Comprehensive hindcast evaluation demonstrates the enhanced reliability and skill of the multimodel ensemble over a more conventional single-model ensemble approach. In addition, innovative examples of the application of seasonal ensemble forecasts in malaria and crop yield prediction are discussed. The strategy followed in DEMETER deals with important problems such as communication across disciplines, downscaling of climate simulations, and use of probabilistic forecast information in the applications sector, illustrating the economic value of seasonal-to-interannual prediction for society as a whole. [ABSTRACT FROM AUTHOR]