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Understanding ice with lasers: New tool helps researchers study remote glaciers


Understanding ice with lasers: New tool helps researchers study remote glaciers

As rising temperatures cause global glaciers to thin and retreat, learn how glaciers are coping climate change, algal growthand impurities such as Dust and black carbon critical. Understanding the response helps scientists, policymakers and communities mitigate harm and protect the watersheds and communities that depend on these glaciers. However, many glaciers are located in remote areas that are difficult to access and study.in a Paper Published in the Journal of Glaciology in May 2022, physicist Markus Allgaier collaborated with geologists and geographers to develop a portable tool that can be easily backpacked and carried to remote glaciers to measure ice optical properties and composition.

Collecting data on the ice composition and retreat of glaciers is important for assessing how glaciers are responding to climate change. The data also helped scientists predict how communities downstream from the glacier might be affected by the retreat of the glacier. Currently, many glaciologists rely on modeling techniques to assess the ice composition of glaciers, especially for more remote glaciers that are inaccessible and difficult to survey. However, it is difficult to accurately measure ice composition, algal growth, and dust and black carbon levels without being on a glacier. This flaw makes backpacking glaciology — trekking to remote areas with portable equipment to take physical measurements of glaciers — essential for understanding ice layers and their behavior.

Remote glaciers, such as Washington’s Deming Glacier, are rarely studied due to their difficult access, especially when heavy equipment is towed. Instead, researchers have had to rely on satellite photos or distant observations, which don’t always give the full picture of glacier retreat. (Courtesy of Jenna Travers)

However, backpacking glaciology requires trade-offs. For portable tools, they are often simple enough to measure variables such as albedo, which are important for understanding retreat. E.g, North Cascade Glacier Climate Projectis a decades-long glacier survey project in northwest Washington that uses long metal probes with detachable sections, laser rangefinders and marked ropes for most of its research. These tools do help researchers gather important data on snow depth, ablation rates, endpoint locations and glacier profiles, but scientists looking to measure albedo or ice composition on remote glaciers have few options available.

Allgaier, a postdoctoral physicist at the University of Oregon, is working to address the lack of options and improve the measurement tools available to glaciologists around the world. In an interview with GlacierHub, Allgaier explained that while his background is in quantum physics, he wants to “apply these fields to environmental science and climate research,” citing his love for mountains and his desire for research focused on understanding them. make a contribution. He starts by looking at what optical measurements glaciologists use, and thinking about how they can be improved and what’s missing from the techniques currently used. He brought in glaciologists, geographers and hydrologists to develop a tool.

These collaborations culminated in the development of a device that uses photons or subatomic light particles to measure the composition and structure of glacial ice. The device fires laser pulses into the glacier ice and measures the time it takes for photons to bounce off the ice and hit a receiver about two meters away. Air bubbles within the glacier scatter laser pulses in random directions, changing the time it takes to hit the receiver and the shape of the pulse when it reaches the receiver. According to Allgaier, “The pulse shape and duration of the detected light are unique, and they tell us how much light is absorbed by the ice and how much is scattered.” This data, in turn, allows the researchers to determine the composition and density of the ice and the optical properties of glaciers. These can be used to predict withdrawal rates.

The device fits into three small cases that fit easily into a backpack. A year ago, Allgaier and his colleagues tested the device on two glaciers in Oregon Falls, and they hope to bring it to Alaska next.Photo: Marcus Alger

Allgaier stressed the importance of the device for both large and small glaciers, saying that by measuring the composition and structure of the ice, the device provides “a glimpse into what causes melting and why the glacier albedo is so.”

While the device is ideal for collecting data on hard-to-access glaciers, it can also be used to verify that remote-sensing data from easily-accessible glaciers is accurate and matches data found on the ground. The latter idea grew out of Allgaier’s collaboration with University of Oregon geographers. Johnny Ryan, assistant professor in the Department of Geography, joined the project to provide perspectives on glaciers, ice sheets, and practical uses for equipment. Ryan said he and his colleagues in the Geography Department were able to advise on how the device could be improved to work best in the field, as well as provide insights into how the project fits into current glaciology research.

According to Ryan, geographers are also helpful when field-testing lasers—knowing where to go, how to navigate glaciers, and how to get permits. The team has already tested it on several glaciers in Oregon: the Crook Glacier at Broken Top Mountain and the Collier Glacier at North Sister. Both tests were successful.

Allgaier used the device on the Collier Glacier last year. Sunlight can disrupt data collection, so researchers had to wait until sunset to test it.Photo: Marcus Alger

So far, only a small fraction of the world’s glaciers have been studied, Ryan said. Going forward, the tool will help researchers “study glaciers that are often unstudied but still important for water resources and sea level rise.” By validating data from satellites and aircraft, the new study has implications for lower glacier communities located in mountains Especially important, these mountains are too dangerous to climb. Understanding how their glaciers are changing and retreating is critical to the future of these communities.




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