Articles | Volume 11, issue 4
The Cryosphere, 11, 1897–1911, 2017

Special issue: International Partnerships in Ice Core Sciences (IPICS) Second...

Special issue: Oldest Ice: finding and interpreting climate proxies in ice...

The Cryosphere, 11, 1897–1911, 2017

Research article 14 Aug 2017

Research article | 14 Aug 2017

High-resolution boundary conditions of an old ice target near Dome C, Antarctica

Duncan A. Young1, Jason L. Roberts2,3, Catherine Ritz4,5, Massimo Frezzotti6, Enrica Quartini1,7, Marie G. P. Cavitte1,7, Carly R. Tozer3, Daniel Steinhage8, Stefano Urbini9, Hugh F. J. Corr10, Tas van Ommen2,3, and Donald D. Blankenship1 Duncan A. Young et al.
  • 1University of Texas Institute for Geophysics, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
  • 2Australian Antarctic Division, Kingston, Australia
  • 3Antarctic Climate and Ecosystems CRC, Hobart, Australia
  • 4CNRS, IGE (UMR5183), 38041 Grenoble, France
  • 5Université Grenoble Alpes, IGE (UMR5183), 38041 Grenoble, France
  • 6ENEA, Rome, Italy
  • 7Department of Geological Sciences, Jackson School of Geosciences, University of Texas at Austin, Austin, Texas, USA
  • 8Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research, Bremerhaven, Germany
  • 9Istituto Nazionale di Geofisica e Vulcanologia, Rome, Italy
  • 10British Antarctic Survey, Cambridge, UK

Abstract. A high-resolution (1 km line spacing) aerogeophysical survey was conducted over a region near the East Antarctic Ice Sheet's Dome C that may hold a 1.5 Myr climate record. We combined new ice thickness data derived from an airborne coherent radar sounder with unpublished data that was in part unavailable for earlier compilations, and we were able to remove older data with high positional uncertainties. We generated a revised high-resolution digital elevation model (DEM) to investigate the potential for an old ice record in this region, and used laser altimetry to confirm a Cryosat-2 derived DEM for inferring the glaciological state of the candidate area. By measuring the specularity content of the bed, we were able to find an additional 50 subglacial lakes near the candidate site, and by Doppler focusing the radar data, we were able to map out the roughness of the bed at length scales of hundreds of meters.

We find that the primary candidate region contains elevated rough topography interspersed with scattered subglacial lakes and some regions of smoother bed. Free subglacial water appears to be restricted from bed overlain by ice thicknesses of less than 3000 m. A site near the ice divide was selected for further investigation. The high resolution of this ice thickness data set also allows us to explore the nature of ice thickness uncertainties in the context of radar geometry and processing.

Short summary
To find records of the greenhouse gases found in key periods of climate transition, we need to find sites of unmelted old ice at the base of the Antarctic ice sheet for ice core retrieval. A joint US–Australian–EU team performed a high-resolution survey of such a site (1 km line spacing) near Concordia Station in East Antarctica, using airborne ice-penetrating radar. We found promising targets in rough subglacial terrain, surrounded by subglacial lakes restricted below a minimum hydraulic head.