January 29, 2014
NASA To Map Iceland’s Winter Glaciers With High-Precision Radar
April Flowers for redOrbit.com - Your Universe Online
This week, a high-precision radar instrument from NASA's Jet Propulsion Laboratory (JPL) left for Iceland to create detailed maps of how glaciers move in the dead of winter. These maps will aid scientists in understanding some of the most basic processes involved in melting glaciers, which are major contributors to rising sea levels.
Mark Simons, a professor of geophysics at the California Institute of Technology in Pasadena, and Brent Minchew, a Caltech graduate student, used the same instrument in June 2012 to map the summer flows of two Icelandic ice caps, which are large areas of permanent snow and ice cover. The caps include multiple glaciers, flowing in different directions and at different speeds.
Surface ice on the glaciers was melting under the summer sun during the 2012 campaign. The speed at which a glacier flows can be influenced by such meltwater when it trickles through the body of the glacier to the bedrock. Mapping these same ice caps in winter, when the surface remains frozen all day, then comparing the summer and winter velocities, will enable the team to isolate the effects of meltwater.
"That’s a challenging subject," said Minchew. "Our understanding of the effects of meltwater on glacier flow is by no means complete. Even the most sophisticated ice sheet models probably are not capturing all of the salient processes."
The campaign will consist of four flights from Keflavik International Airport near Reykjavik, Iceland -- between Jan. 30 and Feb. 6 -- using NASA's C-20A airborne science aircraft and support crew. The four flights will all follow the same complicated path as the campaign in 2012, with crisscrossing flight legs. These legs will allow the Uninhabited Aerial Vehicle Synthetic Aperture Radar (UAVSAR) to map the full extent of both ice caps from multiple angles to capture flows in every direction. The scientists will be able to calculate flow speeds by comparing the movement of the ice between one flight and the next.
"The UAVSAR gives us an entire, continuous map of how every place on the ice cap is moving," Simons said.
According to Simons, the two ice caps -- Hofsjökull and Langjökull -- are ideal natural laboratories for this experiment because they are relatively uncomplicated. The small size of the ice caps also aids the scientists because the data from these experiments can be readily used in computer models of glacier flow without requiring a supercomputer. For example: Langjökull covers about 360 square miles, while the largest ice cap in Iceland -- Vatnajökull -- is more than 3,100 square miles.
Simons said that an even stronger motivation is that "we are benefiting from a huge amount of work on these glaciers that’s already been done by a group of internationally recognized glaciologists in Iceland. The glaciers are in their backyard, and they’ve been studying them for years. They’ve already mapped the ice-rock interface at the bottom of the glacier, for example. We’ve had nothing but support and encouragement from them."