Abstract
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 We combined new ice thickness data derived from an airborne coherent radar sounder with unpublished data that was in part unavailable for earlier compilations, and we were able to remove older data with high positional uncertainties.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.
Highlights
We find that the primary candidate region contains elevated rough topography interspersed with scattered subglacial lakes and some regions of smoother bed
The oldest recovered stratigraphically intact record of Antarctic ice is located in the EPICA Dome C ice core, collected near the joint Italian–French Concordia Station in Wilkes Land, Antarctica (EPICA Community Members, 2004)
We find that both digital elevation model (DEM) have a significant bias, outside the previously demonstrated accuracy of the ICECAP laser system, with the laser altimetry at Dome C; both have very low levels of noise in this very flat region
Summary
The oldest recovered stratigraphically intact record of Antarctic ice is located in the EPICA Dome C ice core, collected near the joint Italian–French Concordia Station in Wilkes Land, Antarctica (EPICA Community Members, 2004). The interpreted section of this ice core, which extends back to 800 ka, records the isotopic and gas imprint of eight glacial cycles with a periodicity of ∼ 100 kyr. Marine records of oxygen isotopes, reveal that prior to 800 ka, the global climate system was driven by shorter, lower-amplitude obliquity-driven ∼ 40 kyr cycles, with an approximately 400 kyr transition between the two states. Young et al.: Boundary conditions of an old ice target
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