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| Titel |
Predictability of extreme values in geophysical models |
| VerfasserIn |
Alef Sterk, Mark Holland, Pau Rabassa, Henk Broer, Renato Vitolo |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090563
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| Publikation (Nr.) |
 EGU/EGU2014-4816.pdf |
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| Zusammenfassung |
| Classical extreme value theory studies the occurrence of unlikely large events. Extreme value
theory was originally developed for time series of near-independent random variables, but in
the last decade the theory has been extended to the setting of chaotic, deterministic
dynamical systems. In the latter context one studies the distribution of large values in a
time series generated by evaluating a scalar observable along evolutions of the
system.
We have studied the finite-time predictability of extreme values, such as convection,
energy, and wind speeds, in three geophysical models. To that end we computed finite-time
Lyapunov exponents (FTLEs) which measure the exponential growth rate of nearby
trajectories over a finite time. In general, FTLEs strongly depend on the initial condition. We
study whether initial conditions leading to extremes typically have a larger or smaller
FTLE.
Our study clearly suggests that general statements about the predictability of
extreme values are not possible: the predictability of extreme values depends on (1)
the observable, (2) the attractor of the system, and (3) the prediction lead time. |
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