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| Titel |
A probabilistic model of chronological errors in layer-counted climate proxies: applications to annually banded coral archives |
| VerfasserIn |
M. Comboul, J. Emile-Geay, M. N. Evans, N. Mirnateghi, K. M. Cobb, D. M. Thompson |
| 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 ; 10, no. 2 ; Nr. 10, no. 2 (2014-04-25), S.825-841 |
| Datensatznummer |
250116956
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| Publikation (Nr.) |
 copernicus.org/cp-10-825-2014.pdf |
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| Zusammenfassung |
| The ability to precisely date climate proxies is central to the
reconstruction of past climate variations. To a degree, all climate proxies
are affected by age uncertainties, which are seldom quantified. This article
proposes a probabilistic age model for proxies based on layer-counted
chronologies, and explores its use for annually banded coral archives. The
model considers both missing and doubly counted growth increments
(represented as independent processes), accommodates various assumptions
about error rates, and allows one to quantify the impact of chronological
uncertainties on different diagnostics of variability. In the case of a
single coral record, we find that time uncertainties primarily affect
high-frequency signals but also significantly bias the estimate of decadal
signals. We further explore tuning to an independent, tree-ring-based
chronology as a way to identify an optimal age model. A synthetic pseudocoral
network is used as testing ground to quantify uncertainties in the estimation
of spatiotemporal patterns of variability. Even for small error rates, the
amplitude of multidecadal variability is systematically overestimated at the
expense of interannual variability (El Niño–Southern Oscillation, or ENSO, in this case), artificially
flattening its spectrum at periods longer than 10 years. An
optimization approach to correct chronological errors in coherent
multivariate records is presented and validated in idealized cases, though it
is found difficult to apply in practice due to the large number of solutions.
We close with a discussion of possible extensions of this model and
connections to existing strategies for modeling age uncertainties. |
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