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| Titel |
Deciphering influences of temperature, moisture sources, post-deposition effects and stratospheric inputs in records of stable isotopes in East Antarctic snow |
| VerfasserIn |
Alexandra Touzeau, Elise Fourré, Mélanie Baroni, Mark Curran, Alexey Ekaykin, Olivier Magand, Andrew Moy, Joe McConnell, Amaëlle Landais |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250104189
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| Publikation (Nr.) |
 EGU/EGU2015-3613.pdf |
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| Zusammenfassung |
| The oxygen and deuterium isotopic composition of ice represent a prodigal source of
information for the reconstruction of past climate. Their widespread use relies upon the
straightforward relationship between the oxygen or deuterium isotopic composition in the
snow precipitated and the inversion temperature (or the local temperature). However, between
the precipitation of the snow and the solidification of ice, several mechanisms may affect the
initial composition of the snow, thereby rendering the climatic signal less perceptible. During
deposition or shortly after deposition, the wind may blow away and redeposit the uncompact
snow, and therefore affect the chronology of the record. Various origins of the moisture
source, including possible stratospheric inputs in very low accumulation sites, may also
affect water isotopic composition. Finally, after deposition, the isotopic signal is
also modified by diffusion of isotopes in the solid phase, local sublimation and
condensation with associated fractionation, and water vapor transport between snow
layers.
In order to assess the effect of these mechanisms on the snow isotopic composition, we
compare the results of the analysis of five snow pits from the East Antarctica plateau: two
from Vostok, one from Dome C, one from S2 and one from Aurora Basin (ABN). For each
snow pit, snow was sampled every three cm over a depth of about three meters.
The ratios of 18O/16O, 17O/16O and D/H were determined for each sample and
additional 10Be profiles were obtained for some profiles. Because the different water
isotopes are affected differently by equilibrium and diffusive processes and because
stratospheric inputs are expected to leave a significant signature in 10Be and 17Oexcess, the
combination of the different isotopic profiles is a useful tool for inferring the origin
of δ18O or δD variations in the top 3 m of the ice sheet. Using the relationships
observed between δ18O, d-excess, 17O-excess and 10Be, we are able to show that
stratospheric input can only be significant at the Vostok station and that the water isotopic
records at Dome C are mainly driven by temperature and post-deposition effect. |
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