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| Titel |
Comparing transient, accelerated, and equilibrium simulations of the last 30 000 years with the GENIE-1 model |
| VerfasserIn |
D. J. Lunt, M. S. Williamson, P. J. Valdes, T. M. Lenton, R. Marsh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 2, no. 2 ; Nr. 2, no. 2 (2006-11-28), S.221-235 |
| Datensatznummer |
250000505
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| Publikation (Nr.) |
 copernicus.org/cp-2-221-2006.pdf |
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| Zusammenfassung |
| We examine several aspects of the ocean-atmosphere system
over the last 30 000 years, by carrying out simulations with
prescribed ice sheets, atmospheric CO2 concentration, and orbital
parameters. We use the GENIE-1 model with a frictional geostrophic ocean,
dynamic sea ice, an
energy balance atmosphere, and a land-surface scheme with fixed
vegetation. A transient simulation, with boundary conditions
derived from ice-core records and ice sheet reconstructions, is compared
with equilibrium
snapshot simulations, including the Last Glacial Maximum (21 000
years before present; 21 kyrBP),
mid-Holocene (6 kyrBP) and pre-industrial. The equilibrium
snapshot simulations are all very similar to their
corresponding time period in the transient simulation, indicating
that over the last 30 000 years, the model's ocean-atmosphere system
is close to equilibrium with its boundary conditions.
However, our simulations neglect the transfer of fresh water from and
to the ocean, resulting from the growth and decay
of ice sheets, which would, in reality, lead to greater disequilibrium.
Additionally, the GENIE-1 model exhibits a rather limited response in
terms of its Atlantic Meridional Overturning Circulation (AMOC)
over the 30 000 years; a more sensitive AMOC would also be likely
to lead to greater disequilibrium. We investigate the method of accelerating
the boundary conditions of a transient simulation and
find that the Southern Ocean is the region most affected
by the acceleration. The Northern Hemisphere, even with a
factor of 10 acceleration, is relatively unaffected. The results
are robust to changes to several tunable parameters in the
model. They also hold when a higher vertical
resolution is used in the ocean. |
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