Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 4, 1051-1075, 2011
© Author(s) 2011. This work is distributed under
the Creative Commons Attribution 3.0 License.
Model description paper
29 Nov 2011
Development and evaluation of an Earth-System model – HadGEM2
W. J. Collins1, N. Bellouin1, M. Doutriaux-Boucher1, N. Gedney1, P. Halloran1, T. Hinton1, J. Hughes1, C. D. Jones1, M. Joshi2, S. Liddicoat1, G. Martin1, F. O'Connor1, J. Rae1, C. Senior1, S. Sitch3, I. Totterdell1, A. Wiltshire1, and S. Woodward1 1Met Office Hadley Centre, Exeter, UK
2National Centres for Atmospheric Science, Climate Directorate, Dept. of Meteorology, University of Reading, Earley Gate, Reading, UK
3School of Geography, University of Leeds, Leeds, UK
Abstract. We describe here the development and evaluation of an Earth system model suitable for centennial-scale climate prediction. The principal new components added to the physical climate model are the terrestrial and ocean ecosystems and gas-phase tropospheric chemistry, along with their coupled interactions.

The individual Earth system components are described briefly and the relevant interactions between the components are explained. Because the multiple interactions could lead to unstable feedbacks, we go through a careful process of model spin up to ensure that all components are stable and the interactions balanced. This spun-up configuration is evaluated against observed data for the Earth system components and is generally found to perform very satisfactorily. The reason for the evaluation phase is that the model is to be used for the core climate simulations carried out by the Met Office Hadley Centre for the Coupled Model Intercomparison Project (CMIP5), so it is essential that addition of the extra complexity does not detract substantially from its climate performance. Localised changes in some specific meteorological variables can be identified, but the impacts on the overall simulation of present day climate are slight.

This model is proving valuable both for climate predictions, and for investigating the strengths of biogeochemical feedbacks.

Citation: Collins, W. J., Bellouin, N., Doutriaux-Boucher, M., Gedney, N., Halloran, P., Hinton, T., Hughes, J., Jones, C. D., Joshi, M., Liddicoat, S., Martin, G., O'Connor, F., Rae, J., Senior, C., Sitch, S., Totterdell, I., Wiltshire, A., and Woodward, S.: Development and evaluation of an Earth-System model – HadGEM2, Geosci. Model Dev., 4, 1051-1075,, 2011.
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