Lab machine to study glacial sliding related to sea levels
Washington: A scientist from Iowa State University in the US has developed a lab machine to study glacial sliding related to rising sea levels.
The scientist in question is Neal Iverson, an Iowa State University professor of geological and atmospheric sciences.
He’s worked for three years on his big new machine, which is over nine feet tall, that he calls a glacier sliding simulator.
At the center of the machine is a ring of ice about eight inches thick and about three feet across.
Below the ice is a hydraulic press that can put as much as 170 tons of force on the ice, creating pressures equal to those beneath a glacier 1,300 feet thick.
Above are motors that can rotate the ice ring at its centerline at speeds of 100 to 7,000 feet per year.
Either the speed of the ice or the stress dragging it forward can be controlled.
Around the ice is circulating fluid - its temperature controlled to 1/100th of a degree Celsius - that keeps the ice at its melting point so it slides on a thin film of water.
As Iverson starts running experiments with the simulator this month, he’ll be looking for data that help explain glacier movement.
“For a particular stress, which depends on a glacier’s size and shape, we’d like to know how fast a glacier will slide,” Iverson said.
Glacier sliding is something that matters far from the ice fields. As the climate warms, Iverson said glaciers slide faster.
When they hit coasts, they dump ice into the ocean. And when those icebergs melt, they contribute to rising sea levels.
But, there’s a lot about the process researchers still don’t know.
“We can’t predict how fast glaciers slide - even to a factor of 10,” Iverson said. “We don’t know enough about how they slide to do that,” he added.
So, Iverson came up with the idea of a glacier in a freezer that allows him to isolate effects of stress, temperature and melt-water on speeds of glacier sliding.
While Iverson had a rough design for the simulator, he said that a team of three engineers from the US Department of Energy’s Ames Laboratory - Terry Herrman, Dan Jones and Jerry Musselman - improved the design and turned it into a working machine.