Journal cover Journal topic
The Cryosphere An interactive open-access journal of the European Geosciences Union
doi:10.5194/tc-2017-23
© Author(s) 2017. This work is distributed
under the Creative Commons Attribution 3.0 License.
Research article
14 Mar 2017
Review status
This discussion paper is under review for the journal The Cryosphere (TC).
Geothermal heat flux and basal melt rate in the DomeC region inferred from radar reflectivity and thermal modelling
Olivier Passalacqua1,2, Catherine Ritz1,2, Frédéric Parrenin1,2, Stefano Urbini3, and Massimo Frezzotti4 1Univ. Grenoble Alpes, LGGE, F-38401 Grenoble, France
2CNRS, LGGE, F-38401 Grenoble, France
3Istituto Nazionale di Geofisica e Vulcanologia, 00143 Roma, Italy
4ENEA, Centro Ricerche Casaccia, PO Box 2400, I-00100, Rome, Italy
Abstract. 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, which is a promising old-ice target. 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 mWm−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.

Citation: Passalacqua, O., Ritz, C., Parrenin, F., Urbini, S., and Frezzotti, M.: Geothermal heat flux and basal melt rate in the DomeC region inferred from radar reflectivity and thermal modelling, The Cryosphere Discuss., doi:10.5194/tc-2017-23, in review, 2017.
Olivier Passalacqua et al.
Olivier Passalacqua et al.
Olivier Passalacqua et al.

Viewed

Total article views: 224 (including HTML, PDF, and XML)

HTML PDF XML Total BibTeX EndNote
164 50 10 224 5 11

Views and downloads (calculated since 14 Mar 2017)

Cumulative views and downloads (calculated since 14 Mar 2017)

Viewed (geographical distribution)

Total article views: 224 (including HTML, PDF, and XML)

Thereof 224 with geography defined and 0 with unknown origin.

Country # Views %
  • 1

Saved

Discussed

Latest update: 27 Mar 2017
Publications Copernicus
Download
Short summary
As the Dome C region is a key area for oldest-ice research, we need to better constrain the geothermal heat flux (GHF) so that past basal melt rates are known well enough. Our inverse heat model significantely reduces the confidence intervals of the GHF regional field. Radar echoes need to be interpreted knowing the time lag of the climate signal to reach the bed. Several old-ice targets are confirmed, and a new one is suggested, where the GHF is very low.
As the Dome C region is a key area for oldest-ice research, we need to better constrain the...
Share