New data on ice sheets in the Antarctic has been gathered using an autonomous underwater vehicle (UAV) named SeaBED. Unlike most UAVs, which have sonar sensors pointing down, SeaBED’s sonar system points upward to measure and map the sea ice floes above. SeaBED was driven back and forth, in a lawn-mowing pattern, at a depth of 65 to 98 feet. The data was then merged to create a high-resolution, 3D bathymetric survey of the underside of the ice. Weighing approximately 440 pounds, the yellow robot features a twin-hull design that provides the stability required for low-speed photographic surveys.
“Putting an AUV together to map the underside of sea ice is challenging from a software, navigation and acoustic communications standpoint,” says Hanumant Singh, an engineering scientist at the Woods Hole Oceanographic Institution where the robot was designed and built. “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. 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.”
Scientists say the data gathered by SeaBED provides far more detail regarding the current state of sea ice. “The full 3-D topography of the underside of the ice provides a richness of new information about the structure of sea ice and the processes that created it. This is key to advancing our models particularly in showing the differences between Arctic and Antarctic sea ice,” says one of the authors of the study involving SeaBED, Guy Williams from Institute of Antarctic and Marine Studies.
Three areas of the Antarctic Penninsula were surveyed, with some ice measuring as much as 55 feet thick. These measurements will need to be taken routinely, in order to track changes over time, the researchers say.