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| Titel |
A delay differential model of ENSO variability – Part 2: Phase locking, multiple solutions and dynamics of extrema |
| VerfasserIn |
I. Zaliapin, M. Ghil |
| 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 ; 17, no. 2 ; Nr. 17, no. 2 (2010-03-22), S.123-135 |
| Datensatznummer |
250013658
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| Publikation (Nr.) |
 copernicus.org/npg-17-123-2010.pdf |
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| Zusammenfassung |
| We consider a highly idealized model for El Niño/Southern
Oscillation (ENSO) variability, as introduced in an earlier paper.
The model is governed by a delay differential equation for
sea-surface temperature T in the Tropical Pacific, and it combines
two key mechanisms that participate in ENSO dynamics: delayed
negative feedback and seasonal forcing. We perform a theoretical and
numerical study of the model in the three-dimensional space of its
physically relevant parameters: propagation period τ of oceanic
waves across the Tropical Pacific, atmosphere-ocean coupling
κ, and strength of seasonal forcing b. Phase locking of
model solutions to the periodic forcing is prevalent: the local
maxima and minima of the solutions tend to occur at the same
position within the seasonal cycle. Such phase locking is a key
feature of the observed El Niño (warm) and La Niña (cold)
events. The phasing of the extrema within the seasonal cycle depends
sensitively on model parameters when forcing is weak. We also study
co-existence of multiple solutions for fixed model parameters and
describe the basins of attraction of the stable solutions in a
one-dimensional space of constant initial model histories. |
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