| 07 Nov 2025
On the use of radar isochrones to improve paleo-ice-sheet model simulations away from ice divides
Abstract. Radio-echo sounding of polar ice masses have revealed extensive isochronal surfaces that have primarily been used to constrain paleo-accumulation rates, geothermal heat flux, and changes in ice-sheet dynamics in stable regions of the ice sheet. However, isochrones remain under-utilised to calibrate ice-sheet models over large spatial scales, particularly in areas far from the stable ice-sheet divide where englacial layering is more disrupted and models likely perform less accurately. Here, we illustrate the utility of isochrones to constrain paleo-ice-sheet simulations in two off-divide areas of the East Antarctic Ice Sheet; the Wilkes Subglacial Basin (WSB) and the Dronning Maud Land (DML) regions. Using airborne radio-echo sounding data from both legacy and newly acquired surveys, and the three-dimensional, thermo-mechanically coupled Parallel Ice-Sheet Model (PISM), we show that traced and dated isochrones are essential for calibrating ice-sheet model simulations in faster-flowing areas of the ice sheet. We highlight the imprint of paleo-climate forcing and model parameterisation that lead to widely different model representations of isochrones with comparable present day representations of ice sheet geometry. Associated with this paper are two datasets of 9 and 7 newly traced isochronal surfaces spanning the Holocene and Last Interglacial (∼4.8–128.4 ka) across the WSB and DML sectors, respectively, which may be used in future modelling studies to assess the paleo-evolution of the Antarctic Ice Sheet. This paper sits at the intersection of data-model integration and highlights further opportunities for using isochrones as boundary conditions in paleo-ice-sheet model simulations.
Competing interests: J.C.R.S. and O.E. are Editor and Advisory Editor of The Cryosphere respectively
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