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.firstname.lastname@example.org
Written by Pam Frost Gorder, (614) 292-9475; Gorder.email@example.com
Images are available from the Polar Geospatial Center or from Pam Frost Gorder
Pamela Gorder | newswise
Welcome Committee for Comets
19.07.2019 | Technische Universität Braunschweig
Sea level rise: West Antarctic ice collapse may be prevented by snowing ocean water onto it
18.07.2019 | Potsdam-Institut für Klimafolgenforschung
Adjusting the thermal conductivity of materials is one of the challenges nanoscience is currently facing. Together with colleagues from the Netherlands and Spain, researchers from the University of Basel have shown that the atomic vibrations that determine heat generation in nanowires can be controlled through the arrangement of atoms alone. The scientists will publish the results shortly in the journal Nano Letters.
In the electronics and computer industry, components are becoming ever smaller and more powerful. However, there are problems with the heat generation. It is...
Scientists have visualised the electronic structure in a microelectronic device for the first time, opening up opportunities for finely-tuned high performance electronic devices.
Physicists from the University of Warwick and the University of Washington have developed a technique to measure the energy and momentum of electrons in...
Scientists at the University Würzburg and University Hospital of Würzburg found that megakaryocytes act as “bouncers” and thus modulate bone marrow niche properties and cell migration dynamics. The study was published in July in the Journal “Haematologica”.
Hematopoiesis is the process of forming blood cells, which occurs predominantly in the bone marrow. The bone marrow produces all types of blood cells: red...
For some phenomena in quantum many-body physics several competing theories exist. But which of them describes a quantum phenomenon best? A team of researchers from the Technical University of Munich (TUM) and Harvard University in the United States has now successfully deployed artificial neural networks for image analysis of quantum systems.
Is that a dog or a cat? Such a classification is a prime example of machine learning: artificial neural networks can be trained to analyze images by looking...
An international research group led by scientists from the University of Bayreuth has produced a previously unknown material: Rhenium nitride pernitride. Thanks to combining properties that were previously considered incompatible, it looks set to become highly attractive for technological applications. Indeed, it is a super-hard metallic conductor that can withstand extremely high pressures like a diamond. A process now developed in Bayreuth opens up the possibility of producing rhenium nitride pernitride and other technologically interesting materials in sufficiently large quantity for their properties characterisation. The new findings are presented in "Nature Communications".
The possibility of finding a compound that was metallically conductive, super-hard, and ultra-incompressible was long considered unlikely in science. It was...
24.06.2019 | Event News
29.04.2019 | Event News
17.04.2019 | Event News
19.07.2019 | Physics and Astronomy
19.07.2019 | Physics and Astronomy
19.07.2019 | Earth Sciences