New software yields highest-resolution large-scale maps of polar ice
The Greenland Ice Sheet is ready for its close-up.
The highest-resolution satellite images ever taken of that region are making their debut. And while each individual pixel represents only one moment in time, taken together they show the ice sheet as a kind of living body—flowing, crumbling and melting out to sea.
The Ohio State University has partnered with the Polar Geospatial Center at the University of Minnesota to turn images captured by DigitalGlobe’s Worldview-1 and 2 satellites into publicly available elevation maps that researchers can use to track the ice.
Ian Howat, associate professor of earth sciences at Ohio State, presented the project’s first data release in a poster session at the American Geophysical Union (AGU) meeting on Dec. 18, 2014.*
He called researchers’ access to DigitalGlobe’s imagery “one of the biggest breakthroughs for earth science satellite capabilities in decades,” adding that “it’s only been a few years since we’ve gotten access to really high-resolution imagery from government agencies, and we’re already discovering new things about the ice sheet.”
The imagery starts out at a resolution of about 0.5 meters. The researchers then turn it into digital elevation maps with a resolution of 2 meters.
With hundreds of terabytes of polar data already collected and additional surface area equivalent to the state of Missouri being collected every day, the researchers are steadily processing it all with new Ohio State software called SETSM (for Surface Extraction from TIN-based Search Minimization). Ohio State research associate Myoung-Jong Noh created the software, which builds 1-gigabyte “tiles” representing regions 7 kilometers on a side and assembles them into mosaics depicting land, sea and ice elevation.
Each tile is extracted from a pair of images acquired of the same region, but about 45 seconds apart. SETSM combines the two displaced images into a coherent whole, as our brain does when it combines images from our two eyes. SETSM uses the Worldview satellites’ sensitivity to a very wide band of the electromagnetic spectrum to show things that our eyes alone couldn’t see, including tiny changes in elevation.
As an example, Howat pointed to the portion of the mosaic showing Jakobshavn Glacier, the fastest-flowing glacier in the Greenland Ice Sheet. Icebergs that have calved off the edge of the glacier are visible floating out to sea—but so are cracks hundreds of kilometers inland from Jakobshavn, on what would otherwise be a flat expanse of ice.
The winding, parallel cracks, which resemble ridges on a fingerprint, are signs that the ice is accelerating, Howat explained. As the ice flows faster and approaches the sea, the surface gets stretched out and cracks open. Over time, the cracks widen. The situation is similar to cars on a highway, he explained: Cars may be bunched up when they first enter the highway from an on-ramp, but they gradually spread apart as they accelerate to highway speeds.
Any research that relies on measuring changes in the Earth’s surface, including studies of volcanoes and coastal erosion, would benefit from elevation data produced by the SETSM software, Howat said. Applications for SETSM outside of earth science include computer vision, astronomy and national security—any job for which very large amounts of terrain are mapped at high resolution.
The mosaics debuting at AGU show southwest Greenland and some of the North Slope of Alaska. So far, the Ohio State team has finished processing images from about one quarter of the Greenland Ice Sheet, representing a tiny portion of the data already stored at Minnesota, and about one year’s worth of work and computing for the research team.
The Greenland Survey, Asiaq, is already using SETSM to protect drinking water resources, where remote sensing specialist Eva Mätzler said it “strengthens the understanding of importance in reliable geographic data for the Greenlandic government and people.” Asiaq project manager Bo Naamansen added that the software “is the best news for several decades when it comes to mapping Greenland and the Arctic.”
Paul Morin, director the Polar Geospatial Center, offered more superlatives: He said that the work done with SETSM is truly revolutionary. “We are no longer limited by remote sensing data when producing elevation data at the poles,” Morin said. “Noh and Howat have shown that we’re really only limited by high-performance computing.”
The Worldview satellite data is collected by commercial imagery vendor DigitalGlobe and licensed for U.S. federal use by the National Geospatial-Intelligence Agency, which in turn provides it to the Polar Geospatial Center at the University of Minnesota. At any given time, a 30-terabyte data subset is being stored and processed at Ohio State via the Ohio Supercomputer Center (OSC) before returning to Minnesota for distribution via a publicly accessible website.
Of the many Ohio State projects that draw upon OSC resources, SETSM is one of the largest. The researchers hope to expand the project to NASA’s Pleiades supercomputer starting in 2015.
NASA funds this research, including the continued development of the SETSM software. The National Science Foundation Division of Polar Programs supports the map distribution through the Polar Geospatial Center. In addition, OSC provided a grant for computing resources.
Contact: Ian Howat, (614) 292-6641; Howat.email@example.com
Written by Pam Frost Gorder, (614) 292-9475; Gorder.firstname.lastname@example.org
Images are available from the Polar Geospatial Center or from Pam Frost Gorder
Pamela Gorder | newswise
Live from the ocean research vessel Atlantis
13.12.2018 | National Science Foundation
NSF-supported scientists present new research results on Earth's critical zone
13.12.2018 | National Science Foundation
The more objects we make "smart," from watches to entire buildings, the greater the need for these devices to store and retrieve massive amounts of data quickly without consuming too much power.
Millions of new memory cells could be part of a computer chip and provide that speed and energy savings, thanks to the discovery of a previously unobserved...
What if, instead of turning up the thermostat, you could warm up with high-tech, flexible patches sewn into your clothes - while significantly reducing your...
A widely used diabetes medication combined with an antihypertensive drug specifically inhibits tumor growth – this was discovered by researchers from the University of Basel’s Biozentrum two years ago. In a follow-up study, recently published in “Cell Reports”, the scientists report that this drug cocktail induces cancer cell death by switching off their energy supply.
The widely used anti-diabetes drug metformin not only reduces blood sugar but also has an anti-cancer effect. However, the metformin dose commonly used in the...
A research team from the University of Zurich has developed a new drone that can retract its propeller arms in flight and make itself small to fit through narrow gaps and holes. This is particularly useful when searching for victims of natural disasters.
Inspecting a damaged building after an earthquake or during a fire is exactly the kind of job that human rescuers would like drones to do for them. A flying...
Over the last decade, there has been much excitement about the discovery, recognised by the Nobel Prize in Physics only two years ago, that there are two types...
12.12.2018 | Event News
10.12.2018 | Event News
06.12.2018 | Event News
14.12.2018 | Power and Electrical Engineering
14.12.2018 | Physics and Astronomy
14.12.2018 | Physics and Astronomy