Through the GRACE satellite program, researchers have shown that the Greenland ice sheet is losing ground 280 billion tons Of ice every year – that’s about 1.5 times Million Olympic swimming pools. For glaciers like those in Greenland and Antarctica, most of that melt water ends up in the ocean – with already noticeable consequences of rising sea levels.
Better predictions of future sea level rise will require us to understand what meltwater is doing inside glaciers – especially below them. But to do so, researchers need to take measurements Across Glacier. Earlier this month, an electrical engineer and ice scientist Dr. Michael Pryor Jones And his assistants in the United Kingdom, Switzerland, Denmark and Canada Published Their redesigned version of the subglacial radio probe–و CryoeggTo help study the “plumbing” of inland glaciers.
The Flow of melt water Glaciers can end up across and below them in small pockets, large lakes, or fast-moving rivers – each destabilizing the glacier above them to different degrees. Subglacial lakes can transform entire parts of a glacier. In contrast, subglacial rivers direct meltwater to a smaller area, causing relatively less glacial movement.
The researchers used radio signals and satellite imagery to determine the size Hydrological networks And lakes under the glaciers. But little is known about the speed at which these waters move or how long they meander on their way to the ocean. The only way to answer these questions is to take measurements under the iceberg.
Glaciers, especially glaciers and drainage holes, called moulins, are too dangerous to explore in person. Melted water pours through the mullein at a rate of 4 metric tons per second, and ice turns frequently. Glaciologists have experimented with experimental fixtures on the tops of glaciers, as well as tentacles dangling through wells in the ice sheet. But these usually only last a few weeks before the glaciers have moved enough to snatch cables or hopelessly tangles and make the setup unusable.
The solution was to design wireless sensors that would launch into the subglacial network. However, it quickly became apparent that researchers could not count on retrieving these measurements when the probes exited the glacier – they were always getting stuck. A series of experiments, including one involving a fleet of Rubber duck Released by NASA, things that go into glaciers are rarely seen again.
This has inspired quite a few devices that transmit measurements in real time Across Ice as the probe moves under the glacier. The most recent one – Cryoegg – has been in operation for nearly 10 years, and Prior Jones and the team explicitly designed it for measurements through deep ice.
Depths of icy
The design is a grapefruit-sized water-resistant, pressure-resistant probe that is now able to send measurements across 1.3 kilometers of ice. It is powered by a battery that allows it to send out measurements every two hours for up to a year. Components include wireless link technology repurposed from water and gas meters in France and a pressure-resistant mechanism case.
Cryoegg is equipped to answer three questions: What is the temperature? How much pressure is there? And how long was the surrounding water flowing through and under the glacier?
The life of water can be approximated by its electrical conductivity. Fresh meltwater is nearly pure, but it flows across the glacier – especially when it comes into contact with rocks and sediments – as it picks up minerals and dissolved solids. These substances, in turn, change the electrical conductivity of water.
Taken together, these measurements provide clues about how rapidly the glacier is depleting. For example, low pressures indicate that water can easily escape, while higher pressures indicate that water is trapped. Also, the higher the conductivity, the more likely the water will remain under the glacier.
“There are currently so few measurements from under the ice that designers have very little data on the effects of changes in the structure of the drainage system,” said Dr Liz Bageshaw, Prior Jones’ collaborator. “We are part of a much larger effort of people measuring all these different processes to be incorporated into broader ice sheet models.”
Waiting in line
Cryoegg has yet to be released for a full trial, but researchers have tested it (tied to a rope) under the Greenland glaciers and the Swiss Alps. With the device having passed all of its tests to date, the team plans to launch the first Cryoegg into the Northeast Greenland Glacier Stream (NEGIS), one of the fastest-moving glaciers known. They hope that measurements from Cryoegg may give them more insights into why these glaciers are moving so fast.
They are also in the process of further compressing Cryoegg and expanding the signal range to 2.5 kilometers of ice – the average depth of the central Greenland ice sheet. Also in the works: expanding the range between the Cryoegg and the radio receiver, not only in terms of depth but also in terms of surface distance.
One of the biggest restrictions at this stage is access to wells, which are usually funded and implemented through international cooperation. Although it would be ideal to eventually deploy the Cryoeggs widely around the world, there is a long line of other researchers waiting to use the wells available for their own studies. In the meantime, the first test will be to see what data is being sent back from Cryoegg’s first flight.
“Glaciology is in some ways equivalent to a space probe because we are sending this little craft into an uncertain environment and hopefully we can recover data from it before it gets lost,” Pryor Jones said.
Kid Kwan is a freelance journalist covering climate and environmental stories for Ars Technica. She has a PhD. In chemistry and chemical biology.