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| Titel |
Optimal localized observations for advancing beyond the ENSO predictability barrier |
| VerfasserIn |
W. Kramer, H. A. Dijkstra |
| 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 ; 20, no. 2 ; Nr. 20, no. 2 (2013-04-02), S.221-230 |
| Datensatznummer |
250018961
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| Publikation (Nr.) |
 copernicus.org/npg-20-221-2013.pdf |
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| Zusammenfassung |
| The existing 20-member ensemble of 50 yr ECHAM5/MPI-OM simulations provides
a reasonably realistic Monte Carlo sample of the El Niño–Southern
Oscillation (ENSO). Localized observations of sea surface temperature (SST),
zonal wind speed and thermocline depth are assimilated in the ensemble using
sequential importance sampling to adjust the weight of ensemble members. We
determine optimal observation locations, for which assimilation yields the
minimal ensemble spread. Efficient observation locations for SST lie in the
ENSO pattern, with the optimum located in the eastern and western Pacific for
minimizing uncertainty in the NINO3 and NINO4 index, respectively. After the
assimilation of the observations, we investigate how the weighted ensemble
performs as a nine-month probabilistic forecast of the ENSO. Here, we focus
on the spring predictability barrier with observation in the January–March
(March–May) period and assess the remaining predictive power in June (August)
for NINO3 (NINO4). For the ECHAM5/MPI-OM ensemble, this yields that SST
observations around 110° W and 140° W provide the best predictive
skill for the NINO3 and NINO4 index, respectively. Forecasts can be improved
by additionally measuring the thermocline depth at 150° W. |
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