The underwater robot beneath the ice, with the propeller of the ice-breaker Aurora Australis visible.
Credit: AUV team/Australian Antarctic Division
For the first time, scientists have made a 3-D map of sea ice in eastern Antarctica.
The map will help reveal the amount of ice in the region, which is important for understanding how climate change is affecting Antarctica.
The Australian researchers, on a two-month voyage to the region on the Australian Antarctic Division's icebreaker Aurora Australis, used helicopters and a special, autonomous underwater vehicle (AUV) to produce a map of both the top and underside of the extensive sea ice, finding peaks and valleys that resemble land topography. This data is a valuable addition, because although satellites can keep tabs on the amount of ice cover, they aren't good at measuring the ice's thickness or volume — information this new 3-D map provides.
Project leader Guy Williams, from the Antarctic Climate and Ecosystems Cooperative Research Centre, said in a statement that the technology represents a huge advance over what researchers had previously used. "In the past, we took drill-line measurements or observed ice thickness as we moved through [the ice] on a ship, but with the AUV, we can now use multi-beam sonar to measure an entire ice floe in unprecedented detail," he said in the statement.
The underwater vehicle swims 65 feet (20 meters) below the ice, traveling in a "lawnmower" grid-pattern and using sonar to make a map of the ice. Data collected by the vehicle is stored in an onboard computer and converted into a 3-D map at the end of each survey.
"The thickness of sea ice is regarded amongst climate scientists as one of the crucial indicators of [climate] change," said researcher Jan Lieser in a statement. "When we know how the thickness of sea-ice cover is changing over time, we can estimate the influence of global climate change on the Antarctic environment."
Changes in sea ice affect formation of the cold, salty Antarctic bottom water that drives ocean currents worldwide and the organisms that depend on the ice for habitat and food, from cold-loving plankton to krill and whales.