Studying glaciers has never been easier than now, as the University of Oregon (UO) unveils a new tool for this purpose that fits in a backpack and can be carried by a single team even on steep slopes.
Around the world, glaciers act as essential sources of fresh water for entire ecosystems and communities. They create incredible and unique landscapes. In the US state of Oregon, glaciers also act as a buffer against late summer droughts and release water even after the annual snowpack has completely melted. This is essential for maintaining the health of species such as salmon and trout.
That being said, glaciers are melting rapidly, both in Oregon and around the world, due to climate change. Our main approach to monitoring this melting has been using satellite data from large glaciers like Greenland and Antarctica. While this can be very useful for large-scale surveillance, getting all the fine details still requires sending people into the field for labor-intensive and quite freezing expeditions.
Researchers at the University of Oregon are working to make those expeditions shorter and easier, however, by developing a portable tool for measuring glacier ice that can work in remote wilderness areas.
Out and about
“Studying how these glaciers respond to climate change is important to inform management of current and future flows,” said Johnny Ryan, a UO geographer who uses the new instrument in his research and co-author of the article describing this. “Many of the processes we observe on Oregon glaciers also occur on the Greenland and Antarctic ice sheets. Oregon glaciers provide an excellent testing ground for new instruments and hypotheses.
The device uses laser beams to measure the composition of glacial ice, recording data that can help determine the rate at which that ice is melting. It is designed to be easily transportable by a single crew and operate in remote areas, such as the Oregon Cascades, for as long as possible. Its main device, which produces the laser beam, fits in a rigid plastic case. All other necessary equipment, such as batteries and cables, fit in a few backpacks.
Its design is, to a large extent, a direct consequence of the state in which it was developed. Oregon’s glaciers rise atop steep mountain slopes. They are located in designated wilderness areas which motorized vehicles are not permitted to enter. This severely limits the amount of heavy equipment or supplies (including power sources) researchers can bring on observation trips.
The new device works by recording how a beam of laser light scatters after contact with glacial ice. The higher the content of air bubbles inside the ice, the more this beam will be scattered. By measuring the time it takes for the photons of the laser beam to reach a detector positioned a few meters from the light source, the team can then estimate the composition of the ice. This can be used to estimate how much sunlight the glacier is absorbing and how much it is reflecting – and this, in turn, is a reliable indicator of how fast it is melting.
In order to test the device, the team first used it on samples in the lab and then tested it around town, just to make sure everything worked as expected.
“With field research, it has to work,” said Markus Allgaier, postdoctoral researcher at UO and lead author of the paper. “You may not get another chance to come back and try again.”
After this first step, they took the device to mountain glaciers; they chose Crook Glacier over Broken Top. The timing of their journey had to be carefully chosen – late enough in summer for the snows to melt from the glacier to expose the bare ice, but before the fresh snow began to fall. They set up their device during the day, but waited until sunset to run the test, as ambient light can interfere with readings. A second trip was made to North Sister’s Collier Glacier, where tests were carried out using the same approach.
Both tests were conclusive and served as “a demonstration of the technique”, the team explains. They add that certain improvements can be made to the device to increase the resolution of the data it retrieves or shorten the measurement time, but these improvements must be weighed against the increases in the cost of the device that they would cause. .
Beyond direct measurement, the device allows researchers to better understand how certain glaciers interact with laser light. Data extracted from this ground-based device can thus be used to ensure that satellite measurements of glaciers are accurate. By giving scientists a reliable tool to correct for inaccuracies in satellite data, this device can help further improve our current monitoring of glacier dynamics and our broader understanding of the climate mechanisms that influence them.
“There are uncertainties about laser penetration in snow and ice,” Ryan said. “We can use our ground-based instrument to measure the depth of green laser penetration in snow and ice and see how it varies in space and time.”
“We hope to bring the instrument to Alaska and use what we learn to ground-truth satellite data,” Allgaier adds.
The article “Direct measurement of the optical properties of glacier ice using diffuse photon-counting LiDAR” was published in the Journal of Glaciology.