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| Titel |
Multiple steady-states in the terrestrial atmosphere-biosphere system: a result of a discrete vegetation classification? |
| VerfasserIn |
A. Kleidon, K. Fraedrich, C. Low |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 4, no. 5 ; Nr. 4, no. 5 (2007-08-28), S.707-714 |
| Datensatznummer |
250001955
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| Publikation (Nr.) |
 copernicus.org/bg-4-707-2007.pdf |
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| Zusammenfassung |
| Multiple steady states in the atmosphere-biosphere system can arise as a
consequence of interactions and positive feedbacks. While atmospheric
conditions affect vegetation productivity in terms of available light, water,
and heat, different levels of vegetation productivity can result in differing
energy- and water partitioning at the land surface, thereby leading to
different atmospheric conditions. Here we investigate the emergence of
multiple steady states in the terrestrial atmosphere-biosphere system and
focus on the role of how vegetation is represented in the model: (i) in terms
of a few, discrete vegetation classes, or (ii) a continuous representation.
We then conduct sensitivity simulations with respect to initial conditions
and to the number of discrete vegetation classes in order to investigate the
emergence of multiple steady states. We find that multiple steady states
occur in our model only if vegetation is represented by a few vegetation
classes. With an increased number of classes, the difference between the
number of multiple steady states diminishes, and disappears completely in our
model when vegetation is represented by 8 classes or more. Despite the
convergence of the multiple steady states into a single one, the resulting
climate-vegetation state is nevertheless less productive when compared to the
emerging state associated with the continuous vegetation parameterization. We
conclude from these results that the representation of vegetation in terms of
a few, discrete vegetation classes can result (a) in an artificial emergence
of multiple steady states and (b) in a underestimation of vegetation
productivity. Both of these aspects are important limitations to be
considered when global vegetation-atmosphere models are to be applied to
topics of global change. |
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