July 14, 2008
CU, NOAA Researchers To Fly Unmanned Planes Over Greenland Ice Sheet To Monitor Melting
University of Colorado and National Oceanic and Atmospheric Administration researchers hoping for a unique glimpse into the workings of the massive Greenland ice sheet are undertaking the first unmanned aerial survey of the island's fast-flowing outlet glacier region.
This month the team is flying two small, crewless planes over a portion of the ice sheet. The goal is to understand how meltwater-fed lakes that dot the surface interact with the ice sheet's dynamic movement and melt rate, said field campaign coordinator John Adler, a CU-Boulder doctoral student and NOAA Corps officer.
In particular, the scientists hope to learn whether the lakes can be used to predict how much water will drain from the ice sheet and contribute to sea-level rise in the future, said Adler. As the glacier moves, it forms cracks, holes and cylindrical vertical shafts in the ice known as "moulins" that allow water to rapidly drain down inside the glacier, he said.
"We want to know how much water is on top of the ice sheet, where it goes, and how much it takes to influence how fast the ice sheet slides to sea," said Adler. Adler is studying under Professor Konrad Steffen, director of the Cooperative Institute for Research in Environmental Sciences, a joint institute of CU-Boulder and NOAA.
Researchers have been closely monitoring Greenland's climate over the past few decades, watching to see if the ice sheet is shrinking over time, said Steffen. Greenland is currently shedding about 50 cubic miles per year, he said.
"We think these marginal melt lakes are responsible for the increase in ice velocity," said Steffen, who maintains his own research camp on the ice sheet and also directs a network of 22 stations on the ice known as the Greenland Climate Network. "They may allow water to drain to the bottom of the ice sheet and lubricate the base."
By using Unmanned Aircraft Systems, or UAS, the researchers will be able to fly instruments at lower altitudes than would be possible with a manned plane and survey little-explored terrain without putting human life at risk, Adler said. The two planes, known as Mantas, were provided by Advanced Ceramics Research Inc. of Tucson, Ariz. Each is less than six feet long and can fit in the bed of a pickup truck.
CIRES researcher Betsy Weatherhead, one of two lead scientists for NOAA's UAS test bed program in the Arctic, called the Greenland effort "the start of a new era of Arctic exploration." Weatherhead said she believes the UAS will prove to be an important tool for monitoring marine mammal populations and the thinning Arctic sea ice.
"With unmanned aircraft systems, we can fly missions too dangerous, dirty or dull for humans to address questions we couldn't even think of addressing before," said Weatherhead.
Each Manta will carry a digital camera, atmospheric temperature and pressure sensors, an ice-surface temperature sensor and a laser range finder to allow researchers to create high-resolution digital elevation models of Greenland's Jakobshavn glacial region, said Steffen. The planes will fly between 500 and 1,000 feet above the surface at speeds of about 45 miles per hour for up to six hours.
Each plane will carry a special camera that will collect information from across the electromagnetic spectrum to probe the depth of lakes on top of the ice sheet, said Adler. By measuring the amount of sunlight penetrating the lake water, researchers can estimate lake depth and the potential amounts of water that could drain through the ice sheet and out to sea, he said.