New high-resolution subglacial bed topography and coastal bathymetry of the Antarctic and Greenland Ice Sheets

The description of the bed topography under the Greenland and Antarctic Ice Sheets has greatly improved over the past decade through new field campaigns and mapping techniques, leading to BedMachine, a high-resolution gridded bed map widely used by the ice-sheet modelling community. Despite regular updates, BedMachine still suffers from uncertainty in ocean bathymetry and mapping artefacts in the ice-sheet interior. We describe here four recent improvements that address these limitations. In Greenland, we use ICESat-2 surface elevation time series to construct an ensemble of bed elevations that captures finer bed details. In Antarctica, we use Ice-Flow Perturbation Analysis in the interior. This approach provides an estimate of the bed topography using the surface expression of mesoscale bedforms. For periphery ice caps and the Antarctic Peninsula, we use the machine learning-based IceBoost approach, which is capable of inferring fine details based on surface features. Finally, over the continental shelf, we use a new gravity inversion product from the Antarctic Gravity Anomaly Grid, which provides significant refinements to the bathymetry around the entire ice sheet. Overall, these represent major improvements in the description of the bed topography and bathymetry for both ice sheets. This article is part of the Theo Murphy meeting issue 'Next generation ice-sheet bed measurements'.