Robot sheds light on Antarctic sea ice

Using an underwater robot built by an Indian-American scientist, a team of international researchers has developed the first detailed, high-resolution 3-D maps of Antarctic sea ice.

The Autonomous Underwater Vehicle (AUV) known as SeaBED provides accurate ice thickness measurements from areas that were previously too difficult to access.

The AUV has been designed, built and operated by Hanumant Singh, an engineering scientist at the Woods Hole Oceanographic Institution (WHOI) in Massachusetts.

SeaBED is approximately two metre-long and weighs nearly 200 kg, has a twin-hull design that gives the robot enhanced stability for low-speed photographic surveys.

The results could step up the pace of research in the polar regions aimed at understanding the dramatic sea ice changes in the context of climate change.

"This work is an important step toward making the kinds of routine measurements we need in order to really monitor and understand what is happening with the ice and the large scale changes that are occurring," said study co-author Ted Maksym, WHOI scientist.

While most oceanographic survey instruments look down at the seafloor, SeaBED was fitted with an upward-looking sonar in order to measure and map the underside of sea ice floes.

The AUV operated at a depth of 20 to 30 meters and was driven in a lawn mower pattern.

These lines of data were merged to form high-resolution 3D bathymetric surveys of the underside of the ice.

"Putting an AUV together to map the underside of sea ice is challenging from a software, navigation and acoustic communications standpoint," said Hanumant Singh, whose lab built the AUV.

"SeaBED's maneuverability 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," he said.

The data from SeaBED, combined with airborne measurements of sea-ice surface elevation, ice coring surveys, and satellite observations, vastly improves scientists' estimates of ice thickness and total sea ice volume.

The study appeared in the journal Nature Geoscience.