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| Titel |
The sensitivity of the Arctic sea ice to orbitally induced insolation changes: a study of the mid-Holocene Paleoclimate Modelling Intercomparison Project 2 and 3 simulations |
| VerfasserIn |
M. Berger, J. Brandefelt, J. Nilsson |
| 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. 2 ; Nr. 9, no. 2 (2013-04-15), S.969-982 |
| Datensatznummer |
250018031
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| Publikation (Nr.) |
 copernicus.org/cp-9-969-2013.pdf |
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| Zusammenfassung |
| In the present work the Arctic sea ice in the mid-Holocene and the
pre-industrial climates are analysed and compared on the basis of
climate-model results from the Paleoclimate Modelling Intercomparison Project
phase 2 (PMIP2) and phase 3 (PMIP3). The PMIP3 models generally simulate
smaller and thinner sea-ice extents than the PMIP2 models both for the
pre-industrial and the mid-Holocene climate. Further, the PMIP2 and PMIP3
models all simulate a smaller and thinner Arctic summer sea-ice cover in the
mid-Holocene than in the pre-industrial control climate. The PMIP3 models
also simulate thinner winter sea ice than the PMIP2 models. The winter
sea-ice extent response, i.e. the difference between the mid-Holocene and the
pre-industrial climate, varies among both PMIP2 and PMIP3 models.
Approximately one half of the models simulate a decrease in winter sea-ice
extent and one half simulates an increase. The model-mean summer sea-ice
extent is 11 % (21 %) smaller in the mid-Holocene than in the
pre-industrial climate simulations in the PMIP2 (PMIP3). In accordance with
the simple model of Thorndike (1992), the sea-ice thickness response to
the insolation change from the pre-industrial to the mid-Holocene is stronger
in models with thicker ice in the pre-industrial climate simulation. Further,
the analyses show that climate models for which the Arctic sea-ice responses
to increasing atmospheric CO2 concentrations are similar may simulate
rather different sea-ice responses to the change in solar forcing between the
mid-Holocene and the pre-industrial. For two specific models, which are
analysed in detail, this difference is found to be associated with
differences in the simulated cloud fractions in the summer Arctic; in the
model with a larger cloud fraction the effect of insolation change is muted.
A sub-set of the mid-Holocene simulations in the PMIP ensemble exhibit open
water off the north-eastern coast of Greenland in summer, which can provide a
fetch for surface waves. This is in broad agreement with recent analyses of
sea-ice proxies, indicating that beach-ridges formed on the north-eastern
coast of Greenland during the early- to mid-Holocene. |
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