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| Titel |
Dynamical implications of prescribing part of a coupled system: Results from a low-order model |
| VerfasserIn |
A. T. Wittenberg, J. L. Anderson |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 5, no. 3 ; Nr. 5, no. 3, S.167-179 |
| Datensatznummer |
250002477
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| Publikation (Nr.) |
 copernicus.org/npg-5-167-1998.pdf |
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| Zusammenfassung |
| It is a common procedure in climate
modelling to specify dynamical system components from an
external source; a prominent example is the forcing of an atmospheric model with observed
sea surface temperatures. In this paper, we examine the dynamics of such forced models
using a simple prototype climate system. A particular fully coupled run of the model is
designated the "true" solution, and an ensemble of perturbed initial states is
generated by adding small errors to the "true" initial state. The perturbed
ensemble is then integrated for the same period as the true solution, using both the
fully-coupled model and a model in which the ocean is prescribed exactly from the true
solution at every time step. Although the prescribed forcing is error-free, the
forced-atmosphere ensemble is shown to converge to spurious solutions. Statistical tests
show that neither the time-mean state nor the variability of the forced ensemble is
consistent with the fully-coupled system. A stability analysis reveals the source of the
inconsistency, and suggests that such behaviour may be a more general feature of models
with prescribed subsystems. Possible implications for model validation and predictability
are discussed. |
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