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| Titel |
The methane record of Daansgard-Oeschger event 17 in Vostok 4G-2 ice core: effects of layered bubble trapping and smoothing |
| VerfasserIn |
Kévin Fourteau, Xavier Faïn, Patricia Martinerie, Amaëlle Landais, Alexey A. Ekaykin, Vladimir Ya. Lipenkov, Jérôme Chappellaz |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148669
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| Publikation (Nr.) |
 EGU/EGU2017-12948.pdf |
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| Zusammenfassung |
| This work aims to characterise and quantify the modification and loss of past atmospheric
information recorded in ice cores due to gas trapping mechanisms. For this purpose a very
high resolution methane record of the DO event 17 in Vostok 4G-2 ice core has been
measured by continuous flow analysis and laser spectroscopy. This is the first time that the
gas of a very low accumulation core, about 1.3cm.yr−1 ice equivalent, is measured using a
continuous method. The measurements reveal numerous anomalous layers a couple of
centimetres thick. These anomalous layers differ in methane mixing ratio from adjacent
layers by about plus or minus 50ppbv. Their amplitude and uneven distribution along the ice
core can be reproduced by a simple layered bubble trapping model. After removing the
layering anomalies, the DO 17 recorded in the Vostok core is clearly smoother than in the
WAIS Divide record, a much higher accumulation rate site. This is consistent with previous
observations and general understanding, since high accumulation firns sink and
densify faster and the trapping phase of gases is less spread over time. However the
smoothing of the DO event in the Vostok ice core turns out to be less important and to
contain higher frequencies than expected. Finally we developed a method to infer the
gas age distribution enclosed in ice cores by comparison with a high frequency
atmospheric scenario, such as the WAIS Divide record. This approach allows to
constrain gas age distributions in climatic conditions which have no modern analogue. |
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