I have some serious doubts about this approach! Apparently, the available radar data of the bedrock of Antarctica was neither incorporated nor compared to.
"... A new approach could change that. Researchers have created a complete map of Antarctica’s bedrock simply by using satellite images of the surface, they report today in Science. The method, which extrapolates from subtle surface undulations in the ice to ascertain the features causing them at depth, could strengthen models of how Antarctica’s ice flows, a critical factor in how much slides into the sea and adds to sea level rise, the team says. ..."
"... A new approach could change that. Researchers have created a complete map of Antarctica’s bedrock simply by using satellite images of the surface, they report today in Science. The method, which extrapolates from subtle surface undulations in the ice to ascertain the features causing them at depth ...
Scientists have been mapping the world below Antarctica for decades using radar. The low-frequency radio waves can penetrate kilometers of clear ice, bouncing off layers in the ice, water, and the bedrock at the bottom. Still, the radars only see directly below them. These campaigns are sometimes separated by 100 kilometers, leaving wide swaths of the continent’s subsurface unexamined ..."
From the editor's summary and abstract:
"Editor’s summary
What do we know about the landscapes beneath the ice of Antarctica? Less than we know about Mercury. To map the continent’s subglacial topography, Ockenden et al. developed a way to invert ice surface satellite data based on the physics of how ice gets perturbed when flowing over bedrock features ... Their map unveils a variety of terrains, including high-relief alpine valleys, scoured lowlands, and deeply eroded ice stream troughs. The landscapes are more varied than presumed by earlier site-specific geophysical surveys, and the newly resolved topography will help to refine projections of ice loss and sea level rise. ...
Abstract
The landscape shrouded by the Antarctic Ice Sheet provides important insights into its history and influences the ice response to climate forcing. However, knowledge of this critical boundary has depended on interpolation between irregularly distributed geophysical surveys, creating major spatial biases in maps of Antarctica’s subglacial landscape. As stress changes associated with ice flow over bedrock obstacles produce ice surface topography, recently acquired, high-resolution satellite maps of the ice surface offer a transformative basis for mapping subglacial landforms.
We present a continental-scale elevation map of Antarctica’s subglacial topography produced by applying the physics of ice flow to ice surface maps and incorporating geophysical ice thickness observations. Our results enrich understanding of mesoscale (2 to 30 kilometers) subglacial landforms and unmask the spatial distribution of subglacial roughness and geomorphology."
What’s below Antarctica’s ice? New map provides clearest view yet "Technique could improve models of how ice flows, bolstering predictions of sea level rise"
Uncovering Antarctica’s ice-draped landscape (Perspective, open access) "The mesoscale topographical variability beneath a continent-scale ice sheet is revealed"
Fig. 1. IFPA subglacial topography of Antarctica.
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