Ninety-eight percent of Antarctica is covered by ice. But hidden underneath is a landscape of mountain chains, valleys, basins, and deeply carved troughs. An international team led by Peter Fretwell and Hamish Pritchard of the British Antarctic Survey has now determined that landscape, and the thickness of the ice sheet above it, with unprecedented detail. To derive the new maps, dubbed Bedmap2, the collaborators compiled decades of geophysical and cartographic data from a variety of sources, including satellite altimetry, interferometry, and gravity missions as well as airborne radar surveys and seismic soundings. The ice-sheet thicknesses in particular were determined from 25 million measurements, two orders of magnitude more than were used for the original Bedmap in 2001. Not only are the data more dense, they are also more precise and cover a larger geographic extent. Thus Bedmap2 reveals numerous new surface and subglacial features, plotted with 1-km resolution.
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