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| Titel |
The role of boundary and initial conditions for dynamical seasonal predictability |
| VerfasserIn |
T. J. Reichler, J. O. Roads |
| 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 ; 10, no. 3 ; Nr. 10, no. 3, S.211-232 |
| Datensatznummer |
250007991
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| Publikation (Nr.) |
 copernicus.org/npg-10-211-2003.pdf |
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| Zusammenfassung |
| The importance of
initial state and boundary forcing for atmospheric predictability is
explored on global to regional spatial scales and on daily to seasonal
time scales. A general circulation model is used to conduct predictability
experiments with different combinations of initial and boundary
conditions. The experiments are verified under perfect model assumptions
as well as against observational data. From initial conditions alone,
there is significant instantaneous forecast skill out to 2 months.
Different initial conditions show different predictability using the same
kind of boundary forcing. Even on seasonal time scales, using observed
atmospheric initial conditions leads to a substantial increase in overall
skill, especially during periods with weak tropical forcing. The impact of
boundary forcing on predictability is detectable after 10 days and leads
to measurable instantaneous forecast skill at very long lead times. Over
the Northern Hemisphere, it takes roughly 4 weeks for boundary conditions
to reach the same effect on predictability as initial conditions. During
events with strong tropical forcing, these time scales are somewhat
shorter. Over the Southern Hemisphere, there is a strongly enhanced
influence of initial conditions during summer. We conclude that the long
term memory of initial conditions is important for seasonal forecasting. |
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