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| Titel |
Continuous Methane and Carbon Monoxide Concentration Measurements along the NEEM Core |
| VerfasserIn |
J. Chappellaz, T. Blunier, X. Faïn, C. Stowasser, V. Gkinis, E. Brook, R. Rhodes, J. McConnell, S. Schüpbach, J. Rosen, R. Dallmayr, O. Pascual, M. Bigler |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250058434
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| Zusammenfassung |
| Since the early 1980s, atmospheric CH4 records have been obtained from ice cores
through discrete sampling and gas chromatographic measurements. Typical sample
resolutions can reach down to decades for certain time periods, with usual uncertainties
of ±10 ppbv. There are very few available CO records, using similar techniques.
Recent developments of optical instruments allow now measurements of CH4 and/or
CO concentration directly on the drill site or in the laboratory using continuous
flow analysis (CFA) systems. The air in the CFA melt stream is extracted with a
hydrophobic membrane unit, dried, and routed through the optical cavity of one or two
instruments in series. We present here the first continuous measurements obtained
along the NEEM (Greenland) core with an unprecedented resolution. The last 2000
years have been measured for both CH4 and CO. CH4 was also measured on older
ice back to the last interglacial. Continuous measurements allow us to determine
with high precision the location in depth of rapid CH4 changes and to discuss finer
structures in the signal. In addition they provide a direct comparison between the
chemical composition of the ice and the gas record at the same depth, thus providing
information about possible local artifacts of trace-gas production within the ice. |
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