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| Titel |
Temperature and precipitation signal in two Alpine ice cores over the period 1961-2001 |
| VerfasserIn |
I. Mariani, A. Eichler  , T. M. Jenk, S. Brönnimann, R. Auchmann, M. C. Leuenberger, M. Schwikowski |
| 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. 3 ; Nr. 10, no. 3 (2014-06-04), S.1093-1108 |
| Datensatznummer |
250116980
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| Publikation (Nr.) |
 copernicus.org/cp-10-1093-2014.pdf |
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| Zusammenfassung |
| Water stable isotope ratios and net snow accumulation in ice cores are
commonly interpreted as temperature or precipitation proxies. However, only
in a few cases has a direct calibration with instrumental data been
attempted. In this study we took advantage of the dense network of
observations in the European Alpine region to rigorously test the
relationship of the annual and seasonal resolved proxy data from two
highly resolved ice cores with local temperature and precipitation. We
focused on the time period 1961–2001 with the highest amount and quality of
meteorological data and the minimal uncertainty in ice core dating
(±1 year). The two ice cores were retrieved from the Fiescherhorn glacier
(northern Alps, 3900 m a.s.l.), and Grenzgletscher (southern Alps, 4200 m a.s.l.).
A parallel core from the Fiescherhorn glacier allowed assessing the
reproducibility of the ice core proxy data. Due to the orographic barrier,
the two flanks of the Alpine chain are affected by distinct patterns of
precipitation. The different location of the two glaciers therefore offers a
unique opportunity to test whether such a specific setting is reflected in the
proxy data. On a seasonal scale a high fraction of δ18O
variability was explained by the seasonal cycle of temperature
(~60% for the ice cores, ~70% for the
nearby stations of the Global Network of Isotopes in Precipitation – GNIP).
When the seasonality is removed, the correlations decrease for all sites,
indicating that factors other than temperature such as changing moisture
sources and/or precipitation regimes affect the isotopic signal on this
timescale. Post-depositional phenomena may additionally modify the ice core
data. On an annual scale, the δ18O/temperature relationship was
significant at the Fiescherhorn, whereas for Grenzgletscher this was the
case only when weighting the temperature with precipitation. In both cases
the fraction of interannual temperature variability explained was
~20%, comparable to the values obtained from the GNIP
stations data. Consistently with previous studies, we found an altitude
effect for the δ18O of −0.17‰/100 m for an
extended elevation range combining data of the two ice core sites and four
GNIP stations. Significant correlations between net accumulation and
precipitation were observed for Grenzgletscher during the entire period of
investigation, whereas for Fiescherhorn this was the case only for the less
recent period (1961–1977). Local phenomena, probably related to wind, seem
to partly disturb the Fiescherhorn accumulation record. Spatial correlation
analysis shows the two glaciers to be influenced by different precipitation
regimes, with the Grenzgletscher reflecting the characteristic precipitation
regime south of the Alps and the Fiescherhorn accumulation showing a pattern
more closely linked to northern Alpine stations. |
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