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article imageRobots en route to Antarctica to study underside of ice shelves

By Karen Graham     Jan 2, 2018 in Science
It has become increasingly common to see cliff-sized chunks of glacial ice falling into the Southern Ocean, suggestive of a warming climate. But scientists don't know what's going on beneath Antarctica's ice sheets., so they are preparing to find out.
With ocean waters warming, they are eating away at the undersides of Antarctica's ice sheet, which acts as a retaining wall to keep the continent's inland glaciers from escaping into the sea.
The warmer ocean waters are forming huge caverns beneath the ice sheets and increasing the danger of the ice above them collapsing. This could cause water levels to rise catastrophically, precipitating the onset of massive flooding in coastal areas.
University of Washington Professor of Oceanography, Craig Lee, is seeking answers, "The contribution of the great ice sheets in the Antarctic and Greenland are the largest sources of uncertainty in our numerical predictions of what sea level rise might be, how it might respond to climate change."
Rift in Pine Island Glacier ice shelf  West Antarctica  photographed from the air during a NASA Oper...
Rift in Pine Island Glacier ice shelf, West Antarctica, photographed from the air during a NASA Operation IceBridge survey flight on November 4, 2016. This rift is the second to form in the center of the ice shelf in the past three years. The first resulted in an iceberg that broke off in 2015.
Nathan Kurth/NASA
To this end, the University of Washington’s College of the Environment, the UW Applied Physics Laboratory and Paul G. Allen Philanthropies have partnered to use a robotic network of underwater drones to observe the conditions beneath a floating Antarctic ice shelf. "This is a high-risk, proof-of-concept test of using robotic technology in a very risky marine environment," says Craig.
It is hoped that observing the water-filled caverns beneath the ice will help in understanding how warmer seawater interacts with the underbelly of the Antarctic ice shelves. According to team member, Knut Christianson, where they are headed is a forbidding region.
"The environment is more dynamic than you might expect. It's not a smooth surface underneath the ice shelf. There are canyons that are tens of hundreds of meters high (Just remember that 100 meters is equal to 328 feet).There are basal crevasses. It's a treacherous environment to explore without knowing a lot about it."
The torpedo-shaped robots (technically underwater drones) are called Seagliders  and they were devel...
The torpedo-shaped robots (technically underwater drones) are called Seagliders, and they were developed with support from the National Science Foundation. The drones will venture into ocean cavities and take readings under the ice.
University of Washington
The use of Seagliders will be unique
The research team will be using Seagliders, Autonomous Underwater Vehicles (AUV), invented by UW oceanographers in the mid-1990s. UW researchers adapted the Seaglider for operating under ice, and have been using it to sample below Arctic sea ice since 2008.
The Seaglider is a research vehicle that scans the oceans autonomously. The Seaglider use very little energy and take advantage of the motions of the sea currents to roam underwater. It is designed to operate at depths of up to 1,000 meters and can work for days without a recharge.
The Seaglider operates in this way: "After each dive, Seaglider dips its nose to raise its antenna out of the water. It determines its position via GPS, calls in via Iridium data telemetry satellite, uploads the oceanographic data it just collected, then downloads a file complete with any new instructions."
Argo float deployment from a research ship.
Argo float deployment from a research ship.
New features on the Seagliders
With the new project in the Antarctic, researchers realized it would be more challenging. Christianson said, "There’s no light penetrating, it’s impossible to communicate with any instruments, and this environment is extremely hard on equipment — picture big crevasses, rushing water and jagged ice.”
The team knew it would have to develop gliders capable of getting in and out of the ice shelf edges without being crushed by moving ice, or swept away by fast-flowing water or trapped in the complex of ridges and crevasses below.
One new technology being used was designed by James Girton, an oceanographer at the UW Applied Physics Laboratory. It will allow the Seagliders to move with the currents while at the same time moving up and down gathering data. The team also devised new navigation algorithms for the Seagliders and tested them in simulations in Puget Sound in November to make sure the instrument can navigate and return safely.
The Thwaites Glacier part of the West Antarctica Ice Sheet is undergoing accelerated melt along with...
The Thwaites Glacier part of the West Antarctica Ice Sheet is undergoing accelerated melt along with a number of other glaciers that could see sea levels rise by between 10 and 13 feet.
During the Antarctic summer, the gliders will travel in and out of caves several times a day, surfacing to download their data. However, when the ocean surface freezes in the Southern Hemisphere winter, the robots will continue to take measurements on their own and will beam data back when they emerge months later in the spring.
The project is very risky. As Craig Lee acknowledges, they're also realistic about the real danger that they might not recover the gliders and floats. As you can imagine, going under the ice shelves is so risky that we don't do it with people and it's risky enough with robotic instruments that more traditional funding agencies might be hesitant to assume that risk, he said. "There's a chance of complete failure when you do this."
Ice shelves like the West Antarctic Ice Sheet play a critical role in maintaining ocean levels  acti...
Ice shelves like the West Antarctic Ice Sheet play a critical role in maintaining ocean levels, acting as retaining walls to keep inland glaciers from escaping into the sea.
Weather Network
And because of the high risk of failure, traditional funding agencies wouldn't touch the project. That is when Microsoft founder Paul Allen, a long-standing ocean climate change research supporter, stepped in, as Spencer Reeder, Director of Climate and Energies for Paul G. Allen Philanthropies, explained. "I think the hope is that we get at least one of these instruments back out from underneath the ice shelf so we get some scientific data. Ideally, we get all of them back but I think we're certainly comfortable with losing a couple of these instruments if that's what happens in the hopes that we get some data back. So that would be a success because it'll be data that's never before been obtained by the scientific community."
The first Seaglider deployment will be under the Pine Island Glacier, if conditions allow, or another nearby extension of the West Antarctic Ice Sheet. In all, three gliders and four ARGO float monitors will be deployed.
The Korean Polar Research Institute (KORPI) is also partnering for this mission. KOPRI will provide field support for the deployments from its icebreaking research vessel Araon, will conduct complementary measurements from the ship and will collaborate on the subsequent analysis of the resulting data, according to the University of Washington.
More about Antarctica, ice shelves, Sea level rise, Seaglider, Global warming
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