, Volume 39, Issue 11, pp 2611-2629
Date: 07 Dec 2011

EC-Earth V2.2: description and validation of a new seamless earth system prediction model

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Abstract

EC-Earth, a new Earth system model based on the operational seasonal forecast system of the European Centre for Medium-Range Weather Forecasts (ECMWF), is presented. The performance of version 2.2 (V2.2) of the model is compared to observations, reanalysis data and other coupled atmosphere–ocean-sea ice models. The large-scale physical characteristics of the atmosphere, ocean and sea ice are well simulated. When compared to other coupled models with similar complexity, the model performs well in simulating tropospheric fields and dynamic variables, and performs less in simulating surface temperature and fluxes. The surface temperatures are too cold, with the exception of the Southern Ocean region and parts of the Northern Hemisphere extratropics. The main patterns of interannual climate variability are well represented. Experiments with enhanced CO2 concentrations show well-known responses of Arctic amplification, land-sea contrasts, tropospheric warming and stratospheric cooling. The global climate sensitivity of the current version of EC-Earth is slightly less than 1 K/(W m−2). An intensification of the hydrological cycle is found and strong regional changes in precipitation, affecting monsoon characteristics. The results show that a coupled model based on an operational seasonal prediction system can be used for climate studies, supporting emerging seamless prediction strategies.

This paper is a contribution to the special issue on EC-Earth, a global climate and earth system model based on the seasonal forecast system of the European Centre for Medium-Range Weather Forecasts, and developed by the international EC-Earth consortium. This special issue is coordinated by Wilco Hazeleger (chair of the EC-Earth consortium) and Richard Bintanja.