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| Titel |
The influence of non-stationary teleconnections on palaeoclimate reconstructions of ENSO variance using a pseudoproxy framework |
| VerfasserIn |
R. Batehup, S. McGregor, A. J. E. Gallant |
| 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 ; 11, no. 12 ; Nr. 11, no. 12 (2015-12-18), S.1733-1749 |
| Datensatznummer |
250117491
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| Publikation (Nr.) |
 copernicus.org/cp-11-1733-2015.pdf |
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| Zusammenfassung |
Reconstructions of the El Niño–Southern Oscillation (ENSO) ideally require
high-quality, annually resolved and long-running palaeoclimate proxy records
in the eastern tropical Pacific Ocean, located in ENSO's centre of action.
However, to date, the palaeoclimate records that have been extracted in the
region are short or temporally and spatially sporadic, limiting the
information that can be provided by these reconstructions. Consequently, most
ENSO reconstructions exploit the downstream influences of ENSO on remote
locations, known as teleconnections, where longer records from palaeoclimate
proxies exist. However, using teleconnections to reconstruct ENSO relies on
the assumption that the relationship between ENSO and the remote location is
stationary in time. Increasing evidence from observations and climate models
suggests that some teleconnections are, in fact, non-stationary, potentially
threatening the validity of those palaeoclimate reconstructions that exploit
teleconnections.
This study examines the implications of non-stationary teleconnections on
modern multi-proxy reconstructions of ENSO variance. The sensitivity of the
reconstructions to non-stationary teleconnections were tested using a suite
of idealised pseudoproxy experiments that employed output from a fully
coupled global climate model. Reconstructions of the variance in the Niño
3.4 index representing ENSO variability were generated using four different
methods. Surface temperature data from the GFDL CM2.1 were used as
pseudoproxies for these reconstruction methods. As well as sensitivity of the
reconstruction to the method, the experiments tested the sensitivity of the
reconstruction to the number of non-stationary pseudoproxies and the location
of these proxies.
We find that non-stationarities can act to degrade the skill of ENSO variance
reconstructions. However, when global, randomly spaced networks (assuming a
minimum of approximately 20 proxies) were employed, the resulting pseudoproxy
ENSO reconstructions were not sensitive to non-stationary teleconnections.
Neglecting proxies from ENSO's centre of action still produced skilful
reconstructions, but with a lower likelihood. Different reconstruction
methods exhibited varying sensitivities to non-stationary pseudoproxies,
which affected the robustness of the resulting reconstructions. The results
suggest that caution should be taken when developing reconstructions using
proxies from a single teleconnected region, or those that use less than 20
source proxies. |
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