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| Titel |
Geothermal heat flux and basal melt rate in the Dome C region inferred from radar reflectivity and thermal modelling. |
| VerfasserIn |
Olivier Passalacqua, Catherine Ritz, Frédéric Parrenin, Stefano Urbini, Massimo Frezzotti |
| 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 |
250141164
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| Publikation (Nr.) |
 EGU/EGU2017-4640.pdf |
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| Zusammenfassung |
| Basal melt rate is the most important physical quantity to be evaluated when looking for an
old-ice drilling site, and it strongly depends on the geothermal heat flux, which is poorly
known under the East Antarctic ice sheet. The wetness of the ice-bed interface can be
assessed from radar echoes on the bedrock, considering that a wet bedrock has a stronger
reflectivity than a dry one. But, as the basal conditions depends on the climatic forcing lagged
by the thick ice, the basal ice may be cold today whereas it was in average temperate in
the past. Accordingly, the risk of mismatch between present and past conditions
must be evaluated, and more generally the geothermal heat flux and basal melt
rate in the Dome C region. Here, we run a 1D heat model over the last 800 ka in
inverse mode to constrain the value of geothermal heat flux by assessing a critical
ice thickness, i.e. the minimum ice thickness that would allow the local melting
distribution at present. A regional map of the geothermal heat flux is then inferred on a 80
km×130 km area, and shows a N-S-oriented gradient, with a value range of 48 −
60 mW m−2. The forward model is then emulated by a polynomial function, to
compute a time-averaged value of the basal melt rate, spatially variable over the
region. Two main subregions appear to be free of basal melting because of the thin
overlying ice, and a third one, north of Dome C, because of a low geothermal heat flux. |
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