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| Titel |
Inferred changes in El Niño–Southern Oscillation variance over the past six centuries |
| VerfasserIn |
S. McGregor, A. Timmermann, M. H. England, O. Elison Timm, A. T. Wittenberg |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1814-9324
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| Digitales Dokument |
URL |
| Erschienen |
In: Climate of the Past ; 9, no. 5 ; Nr. 9, no. 5 (2013-10-10), S.2269-2284 |
| Datensatznummer |
250085229
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| Publikation (Nr.) |
 copernicus.org/cp-9-2269-2013.pdf |
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| Zusammenfassung |
| It is vital to understand how the El Niño–Southern Oscillation (ENSO)
has responded to past changes in natural and anthropogenic forcings, in order
to better understand and predict its response to future greenhouse warming.
To date, however, the instrumental record is too brief to fully characterize
natural ENSO variability, while large discrepancies exist amongst paleo-proxy
reconstructions of ENSO. These paleo-proxy reconstructions have typically
attempted to reconstruct ENSO's temporal evolution, rather than the variance
of these temporal changes. Here a new approach is developed that synthesizes
the variance changes from various proxy data sets to provide a unified and
updated estimate of past ENSO variance. The method is tested using surrogate
data from two coupled general circulation model (CGCM) simulations. It is
shown that in the presence of dating uncertainties, synthesizing variance
information provides a more robust estimate of ENSO variance than
synthesizing the raw data and then identifying its running variance. We also
examine whether good temporal correspondence between proxy data and
instrumental ENSO records implies a good representation of ENSO variance. In
the climate modeling framework we show that a significant improvement in
reconstructing ENSO variance changes is found when combining information from
diverse ENSO-teleconnected source regions, rather than by relying on a single
well-correlated location. This suggests that ENSO variance estimates derived
from a single site should be viewed with caution. Finally, synthesizing
existing ENSO reconstructions to arrive at a better estimate of past ENSO
variance changes, we find robust evidence that the ENSO variance for
any 30 yr period during the interval 1590–1880 was considerably lower than
that observed during 1979–2009. |
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