Editor’s note: The Focus on Research column highlights different research projects being conducted at Penn State. Each column features the work of a different researcher from across all disciplines.
Kiya Riverman headed south before the snow started to fall in Pennsylvania.
But unlike other snowbirds, she didn’t stop in Florida. Her destination wasn’t some tropical beach but rather central west Antarctica — the Penn State graduate student’s winter home for the next two months.
Actually, it’ll be summer on the ice- and snow-covered continent. That means sunshine will stretch around the clock and temperatures might reach a balmy 50 degrees along the coast. But it will be well below zero at the West Antarctic Ice Sheet Divide — the camp where Riverman and a group of five others from Penn State’s College of Earth and Mineral Sciences will conduct research through January.
It’s not Riverman’s first trip to Antarctica, and she knows how to take care of herself there; cover every inch of skin and dress in layers — wool, down and polar fleece.
“My secret weapon is I take a hot water bottle to bed,” she said with a smile in November, just days before she would board a plane and start her journey south.
Though she’s not overly concerned about staying warm, it’s still the temperature that will be on Riverman’s mind for the next two months. Penn State researchers want to be able to take the temperature of Antarctica’s ice sheet.
Riverman and her group, with funding from the National Science Foundation, are experimenting with a method to do just that — using pyrotechnics to measure how long it takes vibrations to travel through the miles-deep glacier.
“The reason we study ice right now in areas where you have rapidly flowing ice, it’s entering the ocean,” Riverman said. “That ice is contributing to sea-level rise. And one of the key controls on the way the ice flows is the temperature of the ice.”
Finding the temperature of the ice and the ground underneath will give scientists a better understanding of where ice is flowing rapidly and why, Riverman said.
The WAIS Divide is a good place to start. Scientists there have drilled deep — more than two miles down — and extracted cores that provide a historical record of the Earth’s climate, and perhaps the key to what might come in the future.
For the group from Penn State, the site offers a rare chance to take direct measurements of temperature at not-normally accessible depths — far into a glacier.
Researchers have developed tools to take those measurements and have tested them during previous research trips. This will be the first year the equipment delivers real science.
That could give scientists new information about conditions under a glacier. But how can researchers test the rest of the continent? Where there isn’t the convenience of a miles-deep hole, determining temperate can be a guessing game.
“We just don’t have a tool for it,” Riverman said. “You have to make educated guesses and connect dots between holes.”
That’s where the pyrotechnics come in. Using dynamite buried just beneath the snow, researchers hope to use vibrations to calculate how much water or sediments are under any given location. The vibrations travel through the ice, down to the bottom of the glacier and then back to the surface.
“How long it takes tells us something about how thick the ice is, and how strong the echo is says something about what the conditions are like under there,” Riverman said. “It’s kind of like if I was yelling at a carpeted wall — I’d hear a quieter echo than if I was yelling at a concrete wall.”
“The idea is temperature of ice really controls how it flows,” Riverman said. “It’s really important to glaciology to know what the temperature structure is of that ice. But you don’t want to go drill a hole everywhere. You can use these methods on the surface to get what the temperature is like three kilometers down.”
If it works, the technique could be applied to seismic data that’s been collected all over the continent, giving scientists a more comprehensive map of temperatures than one with just a few points where holes have been drilled.
Riverman, for one, sees the potential.
“The big social impact questions are what the stability of the ice in the Antarctic is like, and how likely is it to look the same in 100 years,” she said. “In order to answer questions like that, first off, we have to have models. And for that we need temperature. And we just don’t have good tools for getting that. This is going to provide one of those tools that can really inform the models.”