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| Titel |
Last Glacial Maximum world ocean simulations at eddy-permitting and coarse resolutions: do eddies contribute to a better consistency between models and palaeoproxies? |
| VerfasserIn |
M. Ballarotta, L. Brodeau, J. Brandefelt, P. Lundberg, K. Döös |
| 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 ; 9, no. 6 ; Nr. 9, no. 6 (2013-11-28), S.2669-2686 |
| Datensatznummer |
250085267
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| Publikation (Nr.) |
 copernicus.org/cp-9-2669-2013.pdf |
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| Zusammenfassung |
| Most state-of-the-art climate models include a coarsely resolved oceanic
component, which hardly captures detailed dynamics, whereas eddy-permitting
and eddy-resolving simulations are developed to reproduce the observed ocean.
In this study, an eddy-permitting and a coarse resolution numerical
experiment are conducted to simulate the global ocean state for the period of
the Last Glacial Maximum (LGM, ~26 500 to 19 000 yr ago) and to
investigate the improvements due to taking into account the smaller spatial
scales. The ocean state from each simulation is confronted with a data set
from the Multiproxy Approach for the Reconstruction of the Glacial Ocean
(MARGO) sea surface temperatures (SSTs), some reconstructions of the
palaeo-circulations and a number of sea-ice reconstructions. The western
boundary currents and the Southern Ocean dynamics are better resolved in the
high-resolution experiment than in the coarse simulation, but, although these
more detailed SST structures yield a locally improved consistency between
model predictions and proxies, they do not contribute significantly to the
global statistical score. The SSTs in the tropical coastal upwelling zones
are also not significantly improved by the eddy-permitting regime. The models
perform in the mid-latitudes but as in the majority of the
Paleoclimate Modelling Intercomparison Project simulations, the modelled
sea-ice conditions are inconsistent with the palaeo-reconstructions. The
effects of observation locations on the comparison between observed and
simulated SST suggest that more sediment cores may be required to draw
reliable conclusions about the improvements introduced by the high resolution
model for reproducing the global SSTs. One has to be careful with the
interpretation of the deep ocean state which has not reached statistical
equilibrium in our simulations. However, the results indicate that the
meridional overturning circulations are different between the two regimes,
suggesting that the model parametrizations might also play a key role for
simulating past climate states. |
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