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| Titel |
Breeding and predictability in the baroclinic rotating annulus using a perfect model |
| VerfasserIn |
R. M. B. Young, P. L. Read |
| 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 ; 15, no. 3 ; Nr. 15, no. 3 (2008-06-23), S.469-487 |
| Datensatznummer |
250012662
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| Publikation (Nr.) |
 copernicus.org/npg-15-469-2008.pdf |
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| Zusammenfassung |
| We present results from a computational study of predictability in fully-developed
baroclinically unstable laboratory flows. This behaviour is studied in the Met Office/Oxford
Rotating Annulus Laboratory Simulation – a model of the classic rotating annulus laboratory
experiment with differentially heated cylindrical sidewalls, which is firmly established as an
insightful laboratory analogue for certain kinds of atmospheric dynamical behaviour. This work is
the first study of "predictability of the first kind" in the annulus experiment. We devise an ensemble
prediction scheme using the breeding method to study the predictability of the annulus in the perfect
model scenario. This scenario allows one simulation to be defined as the true state, against which all
forecasts are measured. We present results from forecasts over a range of quasi-periodic and chaotic annulus
flow regimes. A number of statistical and meteorological techniques are used to compare the predictability of
these flows: bred vector growth rate and dimension, error variance, "spaghetti plots", probability forecasts,
Brier score, and the Kolmogorov-Smirnov test. These techniques gauge both the predictability of the flow
and the performance of the ensemble relative to a forecast using a climatological distribution. It is found
that in the perfect model scenario, the two quasi-periodic regimes examined may be indefinitely predictable.
The two chaotic regimes (structural vacillation and period doubled amplitude vacillation) show a loss of
predictability on a timescale of hundreds to thousands of seconds (65–280 annulus rotation periods, or 1–3 Lyapunov times). |
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