Underwater robot enables scientists to map Antarctic sea ice

High-res 3D maps will help investigate changes caused by global warming

Antarctic ice floes up to 56ft (17m) thick have been accurately measured for the first time using a submersible robot equipped with upward-looking sonar.

The high resolution 3D maps of Antarctic sea ice, produced by an autonomous underwater vehicle (AUV) known as SeaBed, will help scientists investigating the dramatic polar changes caused by global warming.

The two-metre long sub operates at a depth of 66ft-98ft (20m-30m), bouncing sound waves off the under-surface of the ice.

Professor Mike Meredith, deputy director of science at the British Antarctic Survey, said: "Sea ice is changing in both polar regions, with important consequences for climate and the ecosystem. In contrast to the Arctic, the changes around Antarctica vary from region to region, but full understanding of the causes and impacts of these changes requires detailed knowledge of how thick the ice is, which has historically proven very hard to get.

"Satellites can now give information about this over large areas, but proper interpretation of the satellite data requires direct measurements also. This new research presents important results obtained from a novel underwater vehicle that radically change our concepts of the structure of Antarctic sea ice, and the processes that influence it. Such understanding is key to improving our models of how sea ice will change into the future."

SeaBed was built and operated by engineers from Woods Hole Oceanographic Institution in Massachusetts, US.

Dr Hanumant Singh, a member of the Woods Hole team, said: "Putting an AUV together to map the underside of sea ice is challenging from a software, navigation and acoustic communications standpoint.

"SeaBed's manoeuvrability and stability made it ideal for this application where we were doing detailed floe-scale mapping and deploying, as well as recovering in close-packed ice conditions. It would have been tough to do many of the missions we did, especially under the conditions we encountered, with some of the larger vehicles."

The scientists will now carry out large-scale surveys that can be compared to large-scale observations from aircraft and satellites.