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Titel |
Simulated pre-industrial climate in Bergen Climate Model (version 2): model description and large-scale circulation features |
VerfasserIn |
O. H. Otterå, M. Bentsen, I. Bethke, N. G. Kvamstø |
Medientyp |
Artikel
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Sprache |
Englisch
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ISSN |
1991-959X
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Digitales Dokument |
URL |
Erschienen |
In: Geoscientific Model Development ; 2, no. 2 ; Nr. 2, no. 2 (2009-11-11), S.197-212 |
Datensatznummer |
250000546
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Publikation (Nr.) |
copernicus.org/gmd-2-197-2009.pdf |
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Zusammenfassung |
The Bergen Climate Model (BCM) is a fully-coupled atmosphere-ocean-sea-ice
model that provides state-of-the-art computer simulations of the Earth's
past, present, and future climate. Here, a pre-industrial multi-century
simulation with an updated version of BCM is described and compared to
observational data. The model is run without any form of flux adjustments and
is stable for several centuries. The simulated climate reproduces the general
large-scale circulation in the atmosphere reasonably well, except for a
positive bias in the high latitude sea level pressure distribution. Also, by
introducing an updated turbulence scheme in the atmosphere model a persistent
cold bias has been eliminated. For the ocean part, the model drifts in sea
surface temperatures and salinities are considerably reduced compared to
earlier versions of BCM. Improved conservation properties in the ocean model
have contributed to this. Furthermore, by choosing a reference pressure at
2000 m and including thermobaric effects in the ocean model, a more
realistic meridional overturning circulation is simulated in the Atlantic
Ocean. The simulated sea-ice extent in the Northern Hemisphere is in general
agreement with observational data except for summer where the extent is
somewhat underestimated. In the Southern Hemisphere, large negative biases
are found in the simulated sea-ice extent. This is partly related to problems
with the mixed layer parametrization, causing the mixed layer in the Southern
Ocean to be too deep, which in turn makes it hard to maintain a realistic
sea-ice cover here. However, despite some problematic issues, the
pre-industrial control simulation presented here should still be appropriate
for climate change studies requiring multi-century simulations. |
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