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| Titel |
Assessment of uncertainty in simulations of the mid-Holocene climate |
| VerfasserIn |
Juliane Otto, Thomas Raddatz, Martin Claussen |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040252
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| Zusammenfassung |
| Modelling paleoclimates still represents a challenge for models of all
complexities. For the mid-Holocene, modelling studies agree that the
response of the ocean and the vegetation to the insolation changes feeds back
on the climate. There is less consensus, however, on the relative magnitude of
the two feedbacks and the strength of the synergy between them. This
discrepancy may arise either from statistical uncertainty caused by
internal climate variability or systematic errors due to insufficient model
parameterisation.
We quantify both the statistical and partly the systematic errors by extensive
simulations with the general circulation model ECHAM5/JSBACH-MPIOM.
First, we determine the statistical uncertainty in an ensemble of
centennial-scale simulations. Second, we investigate the sensitivity of the
atmosphere-vegetation feedback with respect to the parameterisation of the
albedo of snow-covered land. This includes the reflectivity of snow as well as
the masking of the snow by boreal forest.
Our study reveals that the divergent results of the previous mid-Holocene
studies can partly be related to the statistical uncertainty. The simulations
including a dynamic ocean show a large variability. This leads to a
sampling error which affects the magnitude of the diagnosed feedbacks.
Furthermore, our results suggest that previous models included a more
sensitive atmosphere-vegetation coupling than ECHAM5/JSBACH. |
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