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
Atmospheric scientists reveal the effect of sea-ice loss on Arctic warming
11.03.2019 | Institute of Atmospheric Physics, Chinese Academy of Sciences
11.03.2019 | University of Tokyo
Nano- and microtechnology are promising candidates not only for medical applications such as drug delivery but also for the creation of little robots or flexible integrated sensors. Scientists from the Max Planck Institute for Polymer Research (MPI-P) have created magnetic microparticles, with a newly developed method, that could pave the way for building micro-motors or guiding drugs in the human body to a target, like a tumor. The preparation of such structures as well as their remote-control can be regulated using magnetic fields and therefore can find application in an array of domains.
The magnetic properties of a material control how this material responds to the presence of a magnetic field. Iron oxide is the main component of rust but also...
Due to the special arrangement of its molecules, a new coating made of corn starch is able to repair small scratches by itself through heat: The cross-linking via ring-shaped molecules makes the material mobile, so that it compensates for the scratches and these disappear again.
Superficial micro-scratches on the car body or on other high-gloss surfaces are harmless, but annoying. Especially in the luxury segment such surfaces are...
The Potsdam Echelle Polarimetric and Spectroscopic Instrument (PEPSI) at the Large Binocular Telescope (LBT) in Arizona released its first image of the surface magnetic field of another star. In a paper in the European journal Astronomy & Astrophysics, the PEPSI team presents a Zeeman- Doppler-Image of the surface of the magnetically active star II Pegasi.
A special technique allows astronomers to resolve the surfaces of faraway stars. Those are otherwise only seen as point sources, even in the largest telescopes...
Researchers at Chalmers University of Technology and the University of Gothenburg, Sweden, have proposed a way to create a completely new source of radiation. Ultra-intense light pulses consist of the motion of a single wave and can be described as a tsunami of light. The strong wave can be used to study interactions between matter and light in a unique way. Their research is now published in the scientific journal Physical Review Letters.
"This source of radiation lets us look at reality through a new angle - it is like twisting a mirror and discovering something completely different," says...
New research group at the University of Jena combines theory and experiment to demonstrate for the first time certain physical processes in a quantum vacuum
For most people, a vacuum is an empty space. Quantum physics, on the other hand, assumes that even in this lowest-energy state, particles and antiparticles...
11.03.2019 | Event News
01.03.2019 | Event News
28.02.2019 | Event News
21.03.2019 | Life Sciences
21.03.2019 | Physics and Astronomy
21.03.2019 | HANNOVER MESSE