Journal
JOURNAL OF GLACIOLOGY
Volume 63, Issue 240, Pages 731-744Publisher
CAMBRIDGE UNIV PRESS
DOI: 10.1017/jog.2017.42
Keywords
Antarctic glaciology; basal melt; ice/ocean interactions; ice-sheet modelling; ice shelves
Funding
- Helmholtz graduate research school GeoSim
- BMBF German Climate Modeling Initiative PalMod
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Ice-shelf basal melting is the largest contributor to the negative mass balance of the Antarctic ice sheet. However, current implementations of ice/ocean interactions in ice-sheet models disagree with the distribution of sub-shelf melt and freezing rates revealed by recent observational studies. Here we present a novel combination of a continental-scale ice flow model and a calibration technique to derive the spatial distribution of basal melting and freezing rates for the whole Antarctic ice-shelf system. The modelled ice-sheet equilibrium state is evaluated against topographic and velocity observations. Our high-resolution (10-km spacing) simulation predicts an equilibrium ice-shelf basal mass balance of -1648.7 Gt a(-1) that increases to -1917.0 Gt a(-1) when the observed ice-shelf thinning rates are taken into account. Our estimates reproduce the complexity of the basal mass balance of Antarctic ice shelves, providing a reference for parameterisations of sub-shelf ocean/ice interactions in continental ice-sheet models. We perform a sensitivity analysis to assess the effects of variations in the model set-up, showing that the retrieved estimates of basal melting and freezing rates are largely insensitive to changes in the internal model parameters, but respond strongly to a reduction of model resolution and the uncertainty in the input datasets.
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