Joint Inversion for Surface Accumulation Rate and Geothermal Heat Flow From Ice-Penetrating Radar Observations at Dome A, East Antarctica. Part II: Ice Sheet State and Geophysical Analysis

Dome A is the summit of the East Antarctic Ice Sheet, underlain by the rugged Gamburtsev Subglacial Mountains. The rugged basal topography produces a complex hydrological system featuring basal melt, water transport and storage, and freeze-on. In a companion study, we used an inverse model to infer the spatial distributions of geothermal heat flow (GHF) and accumulation rate that best fit a variety of observational constraints. Here, we present and analyze the best-fit state of the ice sheet in detail. Our modeled result 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. Our modeled stratigraphy agrees well with observations, and we predict that there will be two distinct patches of ice up to 1.5 Ma suitable for ice coring underneath the divide. Past divide migration could have interrupted stratigraphic continuity at the old ice patches, but various indirect lines of evidence suggest that the divide has been stable for about the last one and a half glacial cycles, which is an encouraging but not definitive sign for stability in the longer term. Finally, our GHF estimate is higher than previous estimates for this region, but consistent with possible heterogeneity in crustal heat production.