Journal cover Journal topic
Geoscientific Model Development An interactive open-access journal of the European Geosciences Union
Geosci. Model Dev., 5, 1161-1175, 2012
© Author(s) 2012. This work is distributed under
the Creative Commons Attribution 3.0 License.
Model description paper
19 Sep 2012
Simulating Southern Hemisphere extra-tropical climate variability with an idealised coupled atmosphere-ocean model
H. Kurzke1,*, M. V. Kurgansky2, K. Dethloff1, D. Handorf1, S. Erxleben1, D. Olbers3, C. Eden4, and M. Sempf5,** 1Alfred Wegener Institute for Polar and Marine Research, Research Unit Potsdam, Potsdam, Germany
2A. M. Obukhov Institute of Atmospheric Physics, Russian Academy of Sciences, Moscow, Russia
3Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany
4Institute of Oceanography, University of Hamburg, Hamburg, Germany
5SDA Software Design Ahnert GmbH, Berlin, Germany
*current address: Institute for Physics and Astronomy, Potsdam University, Potsdam, Germany
**formerly at: Max Planck Institute for Plasmaphysics, Muenchen-Garching, Germany
Abstract. A quasi-geostrophic model of Southern Hemisphere's wintertime atmospheric circulation with horizontal resolution T21 has been coupled to a global ocean circulation model with a resolution of 2° × 2° and simplified physics. This simplified coupled model reproduces qualitatively some features of the first and the second EOF of atmospheric 833 hPa geopotential height in accordance with NCEP data. The variability patterns of the simplified coupled model have been compared with variability patterns simulated by four complex state-of-the-art coupled CMIP5 models. The first EOF of the simplified model is too zonal and does not reproduce the right position of the centre of action over the Pacific Ocean and its extension to the tropics. The agreement in the second EOF between the simplified and the CMIP5 models is better. The total variance of the simplified model is weaker than the observational variance and those of the CMIP5 models. The transport properties of the Southern Ocean circulation are in qualitative accord with observations. The simplified model exhibits skill in reproducing essential features of decadal and multi-decadal climate variability in the extratropical Southern Hemisphere. Notably, 800 yr long coupled model simulations reveal sea surface temperature fluctuations on the timescale of several decades in the Antarctic Circumpolar Current region.

Citation: Kurzke, H., Kurgansky, M. V., Dethloff, K., Handorf, D., Erxleben, S., Olbers, D., Eden, C., and Sempf, M.: Simulating Southern Hemisphere extra-tropical climate variability with an idealised coupled atmosphere-ocean model, Geosci. Model Dev., 5, 1161-1175,, 2012.
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