Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 9, 3859-3873, 2016
https://doi.org/10.5194/gmd-9-3859-2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Methods for assessment of models
01 Nov 2016
Transient simulations of the present and the last interglacial climate using the Community Climate System Model version 3: effects of orbital acceleration
Vidya Varma1,a, Matthias Prange1,2, and Michael Schulz1,2 1MARUM – Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
2Faculty of Geosciences, University of Bremen, Bremen, Germany
anow at: National Institute of Water and Atmospheric Research, Wellington, New Zealand
Abstract. Numerical simulations provide a considerable aid in studying past climates. Out of the various approaches taken in designing numerical climate experiments, transient simulations have been found to be the most optimal when it comes to comparison with proxy data. However, multi-millennial or longer simulations using fully coupled general circulation models are computationally very expensive such that acceleration techniques are frequently applied. In this study, we compare the results from transient simulations of the present and the last interglacial with and without acceleration of the orbital forcing, using the comprehensive coupled climate model CCSM3 (Community Climate System Model version 3). Our study shows that in low-latitude regions, the simulation of long-term variations in interglacial surface climate is not significantly affected by the use of the acceleration technique (with an acceleration factor of 10) and hence, large-scale model–data comparison of surface variables is not hampered. However, in high-latitude regions where the surface climate has a direct connection to the deep ocean, e.g. in the Southern Ocean or the Nordic Seas, acceleration-induced biases in sea-surface temperature evolution may occur with potential influence on the dynamics of the overlying atmosphere.

Citation: Varma, V., Prange, M., and Schulz, M.: Transient simulations of the present and the last interglacial climate using the Community Climate System Model version 3: effects of orbital acceleration, Geosci. Model Dev., 9, 3859-3873, https://doi.org/10.5194/gmd-9-3859-2016, 2016.
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Short summary
We compare the results from simulations of the present and the last interglacial, with and without acceleration of the orbital forcing, using a comprehensive coupled climate model. In low latitudes, the simulation of long-term variations in interglacial surface climate is not significantly affected by the use of the acceleration technique and hence model–data comparison of surface variables is therefore not hampered but major repercussions of the orbital forcing are obvious below thermocline.
We compare the results from simulations of the present and the last interglacial, with and...
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