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| Titel |
Influence of solar variability, CO2 and orbital forcing between 1000 and 1850 AD in the IPSLCM4 model |
| VerfasserIn |
J. Servonnat, P. Yiou, M. Khodri, D. Swingedouw, S. Denvil |
| 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 ; 6, no. 4 ; Nr. 6, no. 4 (2010-07-22), S.445-460 |
| Datensatznummer |
250003653
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| Publikation (Nr.) |
 copernicus.org/cp-6-445-2010.pdf |
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| Zusammenfassung |
Studying the climate of the last millennium gives the possibility to deal
with a relatively well-documented climate essentially driven by natural
forcings. We have performed two simulations with the IPSLCM4 climate model
to evaluate the impact of Total Solar Irradiance (TSI), CO2 and orbital
forcing on secular temperature variability during the preindustrial part of
the last millennium. The Northern Hemisphere (NH) temperature of the
simulation reproduces the amplitude of the NH temperature reconstructions
over the last millennium. Using a linear statistical decomposition we
evaluated that TSI and CO2 have similar contributions to secular
temperature variability between 1425 and 1850 AD. They generate a
temperature minimum comparable to the Little Ice Age shown by the
temperature reconstructions. Solar forcing explains ~80% of the NH
temperature variability during the first part of the millennium (1000–1425
AD) including the Medieval Climate Anomaly (MCA). It is responsible for a
warm period which occurs two centuries later than in the reconstructions.
This mismatch implies that the secular variability during the MCA is not
fully explained by the response of the model to the TSI reconstruction.
With a signal-noise ratio (SNR) estimate we found that the temperature
signal of the forced simulation is significantly different from internal
variability over area wider than ~5.106 km2, i.e. approximately
the extent of Europe. Orbital forcing plays a significant role in latitudes
higher than 65° N in summer and supports the conclusions of a recent
study on an Arctic temperature reconstruction over past two millennia. The
forced variability represents at least half of the temperature signal on
only ~30% of the surface of the globe. This study suggests that
regional reconstructions of the temperature between 1000 and 1850 AD are
likely to show weak signatures of solar, CO2 and orbital forcings
compared to internal variability. |
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