Underwater robot studying ice-covered Antarctic Ocean

October 23, 2010 - via CTV.ca

An underwater robot owned by the University of British Columbia is probing the ice-covered waters off Antarctica as part of a project designed to give scientists a rare glimpse into the forbidding depths at the South Pole.

Until now, scientists have had a hard time figuring out exactly what's going on in the deep, frigid waters beneath the ice shelves that cling to 44 per cent of the Antarctic coastline.

Traditional depth profiling instruments are dropped through a limited number of drill holes, providing a limited vertical profile of water temperature, salinity and other variables. In contrast, a robot that can dive, collect data and return to its starting point autonomously has the potential to advance scientists' perspective from knowing what's going on in a narrow column of water to having a dynamic 3-D perspective of the largely uncharted ice-covered waters. Ultimately, researchers hope data they collect from beneath the ice will be used to better understand the global climate.

"The bigger goal is to actually help the climate modelers get a better idea of how these ice-ocean interfaces are reacting to changes in the ocean," UBC doctoral candidate Andrew Hamilton told CTV News in an interview from Christchurch, New Zealand. "We have a fairly good understanding of how ice masses react to atmospheric changes, but we really don't have a good understanding of what's happening underneath these masses at the water interface."

Hamilton is one of the team of scientists and engineers from New Zealand, Canada, the United States and France who are trying to gain a better understanding of the processes that affect how ice shelves freeze, melt, break apart and mix with ocean water.

Their 2.5-metre long Autonomous Underwater Vehicle, dubbed UBC-Gavia, is equipped with temperature and salinity sensors, current meters, mapping sonar, a digital camera and water quality optical sensors. UBC Assoc. Prof. Bernard Laval, who heads the university's AUV and Fluid Mechanics research group, expects the project to offer unprecedented access to the ice-covered waters. "Few labs in the world are able to investigate the spatial variability of ocean properties under ice," Laval said in a statement announcing the project. "Findings from this study will be unique as there have only been a few under-ice AUV deployments globally, even fewer in the vicinity of ice shelves."

Before each AUV mission, Hamilton and Alexander Forrest program the robot's route and sensor protocols.
Once the instructions are uploaded, the robot is deployed through a hole in the 2-metre thick ice of the Erebus Glacier Tongue -- a 12-kilometre long stretch of ice floating in McMurdo Sound off Ross Island. Scientists will use the data recorded beside and under the glacier tongue as a proxy for the processes occurring at a much larger scale under the ice shelves.

Compared to the glacier tongue, ice shelves are much thicker floating sheets of ice formed where glaciers or other land-formed ice flows from onto the ocean surface. "Where they contact the ocean there's lost of currents and thermal properties that we know influence whether the glaciers are freezing or melting, but we really need to get underneath to understand how the ocean is influencing this," Hamilton explained.

Ice shelves only exist in Canada, where four remain attached to Ellesmere Island, Greenland and Antarctica.
Sea ice surrounding Antarctica is expected to decline more than one-third by 2100. In turn, scientists expect that to accelerate the collapse of the ice shelves.

The month-long study -- part of the Antarctica 2010 Glacier Tongues and Ocean Mixing Research Project led by investigator Craig Stevens at the New Zealand National Institute for Water and Atmospheric Research -- continues until Nov. 12.

External link: http://www.ctv.ca/CTVNews/TopStories/20101023/antarctica-ubc-gavia-101023/

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