Published on July 25th, 2008 | by Timothy B. Hurst23
Robot Planes Getting Bird’s Eye View of Shrinking Greenland Ice Sheet
Two low-flying unmanned aircraft are cruising over Greenland this month to closely observe the melting of the Greenland Ice Sheet and its potential contribution to global sea level rise in the coming century. The flights will help scientists determine whether the ice sheet’s melt rate will accelerate in the future.
The drones are flying out of Ilulissat, half way up Greenland’s west coast, for three weeks through the end of this month. Scientists studying the rapidly vanishing Greenland ice sheet need to fill gaps in their data that was collected through satellite imagery.
A spurt of innovative unmanned aircraft missions have recently been flown including those that will deliver maps to help fight this year’s California wildfires, to scrutinize atmospheric pollution levels, and to study Atlantic and Gulf hurricanes.
“We’re seeing the start of a new era in Arctic exploration,” said scientist Betsy Weatherhead, of NOAA’s Earth System Research Laboratory and the Cooperative Institute for Research in Environmental Sciences. “With unmanned aircraft systems, we can fly missions too dangerous, dirty, or dull for humans and address questions we couldn’t even think of addressing before.”
In the ongoing Greenland ice sheet mission, the unmanned “Manta” vehicles are controlled by operators from the aircraft’s manufacturer, Advanced Ceramics Research (ACR), under the direction of on-site scientists. The eight-foot-wide, 45-pound Mantas will carry a digital camera, atmospheric temperature and pressure sensors, and other instruments. Carrying a full 15-pound instrument payload, the Manta can fly for up to six hours at about 40 knots, or 45 miles per hour, according to the Advanced Ceramics website.
Scientists now studying the Jakobshavn glacier in Greenland found its melt rate has doubled in the past decade with the resulting ice stream moving nearly 120 feet per day. According to NASA satellite measurements, the Greenland Ice Sheet is melting at a rate of 57.3 cubic miles per year.
In summer months, the sun melts the top layer of the glaciers to form little lakes throughout the region, many of which vanish within a day. Scientists think these lakes may be emptying out through the ice and lubricating the bottom of the glacier with water. The glacier can then slide more quickly down the valleys, eventually breaking off into icebergs at the coastline.
In an August 2007 article, (sub. req’d.) glaciologist Dr. Konrad Steffen, explained the problem of so-called “dynamic response” this way:
“What happens is that the melting accelerates as meltwater funnels down to the bedrock. At the bottom, the water acts as a lubricant, flowing under the outlet glaciers and allowing the ice to slip into the sea more quickly.”
A bird’s-eye view of the region from 500 to 1,000 feet above the ice will provide fine-scale measurements of the water and surface of the glaciers. Low-flying, unmanned Mantas are able to provide that view by cruising at low altitudes over little-known terrain without putting human life at risk.
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Photos: 1. ACR; 2. ACR; 3. NOAA;