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| Titel |
Oscillations in a simple climate-vegetation model |
| VerfasserIn |
J. Rombouts, M. Ghil |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
2198-5634
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics Discussions ; 2, no. 1 ; Nr. 2, no. 1 (2015-02-02), S.145-178 |
| Datensatznummer |
250115146
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| Publikation (Nr.) |
 copernicus.org/npgd-2-145-2015.pdf |
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| Zusammenfassung |
We formulate and analyze a simple dynamical systems model for
climate–vegetation interaction. The planet we consider
consists of a large ocean and a land surface on which
vegetation can grow. The temperature affects vegetation growth
on land and the amount of sea ice on the ocean. Conversely,
vegetation and sea ice change the albedo of the planet, which
in turn changes its energy balance and hence the temperature
evolution. Our highly idealized, conceptual model is governed
by two nonlinear, coupled ordinary differential equations, one
for global temperature, the other for vegetation cover. The
model exhibits either bistability between a vegetated and a
desert state or oscillatory behavior. The oscillations arise
through a Hopf bifurcation off the vegetated state, when the
death rate of vegetation is low enough. These oscillations
are anharmonic and exhibit a sawtooth shape that is
characteristic of relaxation oscillations, as well as
suggestive of the sharp deglaciations of the Quaternary.
Our model's behavior can be compared, on the one hand, with
the bistability of even simpler, Daisyworld-style
climate–vegetation models. On the other hand, it can be
integrated into the hierarchy of models trying to simulate and
explain oscillatory behavior in the climate system. Rigorous
mathematical results are obtained that link the nature of the
feedbacks with the nature and the stability of the
solutions. The relevance of model results to climate
variability on various time scales is discussed. |
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