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| Titel |
Simulating the temperature and precipitation signal in an Alpine ice core |
| VerfasserIn |
S. Brönnimann, I. Mariani, M. Schwikowski, R. Auchmann, A. Eichler  |
| 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. 4 ; Nr. 9, no. 4 (2013-08-22), S.2013-2022 |
| Datensatznummer |
250085211
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| Publikation (Nr.) |
 copernicus.org/cp-9-2013-2013.pdf |
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| Zusammenfassung |
| Accumulation and δ18O data from Alpine ice cores provide
information on past temperature and precipitation. However, their correlation
with seasonal or annual mean temperature and precipitation at nearby sites is
often low. This is partly due to the irregular sampling of the atmosphere by
the ice core (i.e. ice cores almost only record precipitation events and not
dry periods) and the possible incongruity between annual layers and calendar
years. Using daily meteorological data from a nearby station and reanalyses,
we replicate the ice core from the Grenzgletscher (Switzerland,
4200 m a.s.l.) on a sample-by-sample basis by calculating
precipitation-weighted temperature (PWT) over short intervals. Over the last
15 yr of the ice core record, accumulation and δ18O variations can
be well reproduced on a sub-seasonal scale. This allows a wiggle-matching
approach for defining quasi-annual layers, resulting in high correlations
between measured quasi-annual δ18O and PWT. Further back in time,
the agreement deteriorates. Nevertheless, we find significant correlations
over the entire length of the record (1938–1993) of ice core δ18O
with PWT, but not with annual mean temperature. This is due to the low
correlations between PWT and annual mean temperature, a characteristic which
in ERA-Interim reanalysis is also found for many other continental mid-to-high-latitude regions. The fact that meteorologically very different years
can lead to similar combinations of PWT and accumulation poses limitations to
the use of δ18O from Alpine ice cores for temperature
reconstructions. Rather than for reconstructing annual mean temperature,
δ18O from Alpine ice cores should be used to reconstruct PWT over
quasi-annual periods. This variable is reproducible in reanalysis or climate
model data and could thus be assimilated into conventional climate models. |
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