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Joint Inversion for Surface Accumulation and Geothermal Flux from Ice-Penetrating Radar Observations at Dome A, East Antarctica. Part II: Ice Sheet State and Geophysical Analysis
  • Michael J. Wolovick,
  • John Christopher Moore,
  • Liyun Zhao
Michael J. Wolovick
Beijing Normal University

Corresponding Author:[email protected]

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John Christopher Moore
Beijing Normal University
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Liyun Zhao
Beijing Normal University
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Abstract

Dome A is the peak of the East Antarctic Ice Sheet (EAIS), underlain by the rugged Gamburtsev Subglacial Mountains (GSM). The rugged basal topography produces a complex hydrological system featuring basal melt, water transport and storage, and freeze-on. In a companion paper, we used an inverse model to infer the spatial distributions of geothermal flux and accumulation rate that best fit a vareity of observational constraints. Here, we present and analyze the best-fit state of the ice sheet in detail. Our model agrees well with the observed water bodies and freeze-on structures, while also predicting a significant amount of unobserved water and suggesting a change in stratigraphic interpretation that reduces the volume of the freeze-on units. We predict that a weak Raymond effect underneath the ice divide has been mostly masked by the high-amplitude variability in the layers produced by draping over subglacial topography. Our model stratigraphy agrees well with observations, and we predict- assuming that the ice divide has been stable over time- that there will be two distinct patches of ice older than 1 Ma suitable for ice coring underneath the divide. Finally, our geothermal flux estimate is substantially higher than previous estimates for this region. Correcting for the bias induced by unresolved narrow valleys still leaves our result in the high end of past estimates, with substantial local anomalies that are hotter still. Fundamentally, the observational evidence of a complex basal hydrological system is inconsistent with a simple picture of a uniformly cold East Antarctic craton.