Study provides new tool to probe meltwater drainage should also help project glacial response to climate change, says University of Oregon researcher
Erosion by summertime melt-driven streams on Greenland's ice sheet shapes landscapes similarly to, but much faster than, rivers do on land, says a University of Oregon geologist.
The approach used to study the ice sheet should help to broaden scientific understanding of melt rates and improve projections about glacial response to climate change, says Leif Karlstrom, a professor in the UO Department of Geological Sciences.
The study, online ahead of print in the journal Geophysical Research Letters, also found that the topography of Greenland's bedrock below the slowly flowing ice sheet has a role in the formation of basins in the ice above as high-elevation streams make their way downward toward the sea.
"How fast is the ice sheet melting, and how much the melt will contribute to rising sea levels are important questions," Karlstrom said. "It is important to quantify the melt rate, but that is not easy. Our study allows us to use geometric characteristics of the channel network -- their patterns on the landscape -- as a diagnostic tool."
Projections on sea-level rise, such as those done with remote sensing or satellite observations, he said, have been difficult to determine accurately because melt rates vary widely each year, based on such factors as summer temperatures and elevations across the ice sheet.
In the study, Karlstrom and Kang Yang of the University of California, Los Angeles analyzed high-resolution satellite imagery from NASA digital elevation models that let them see the slope of the ice sheet and underlying bedrock. They focused on stream channels at four levels of the ice sheet, from 1,000 meters (3,280 feet) to 1,600 meters (5,249 feet), of southwest Greenland.
Geometrical characteristics of these streams -- called supraglacial channels because they occur on the ice surface -- mimic features often found for rivers on land. Such similarities of erosion patterns on ice and land, despite having different mechanisms, came as a surprise, Karlstrom said. On the ice sheet surface, erosion occurs as meltwater streams carve drainage channels by melting underlying ice. On land, rivers carve drainage channels by pushing and plucking sediment as they flow toward the sea, cutting down as the land surface uplifts due to tectonic activity.
Geologists who study geomorphology -- how landscapes form -- now have a virtual real time model to test theories of landscape evolution, Karlstrom said. River erosion on land occurs over millions of years, but streams on the ice sheet carve their routes much more rapidly. In the study, researchers documented daily incision by flowing meltwater of up to 10 centimeters (4 inches).
"It's lower elevations at the margins of the ice sheet that experience the most melt," Karlstrom said. River erosion stops each year when freezing temperatures return. Frozen channels from previous years remain visible, providing a yearly history of erosion patterns much like tree rings reflect age, he said.
In addition to using glacial melt to test theories of land-based geological processes, the researchers suggest an application to studies of other planets.
Part of the project was supported by a NASA grant (NNX14AH93G) to Yang.
Source: Leif Karlstrom, assistant professor of geological sciences, firstname.lastname@example.org
Note: The UO is equipped with an on-campus television studio with a point-of-origin Vyvx connection, which provides broadcast-quality video to networks worldwide via fiber optic network. There also is video access to satellite uplink and audio access to an ISDN codec for broadcast-quality radio interviews.
Paper abstract: http://onlinelibrary.
Karlstrom faculty page: http://pages.
UO Department of Geological Sciences: http://geology.
Jim Barlow | EurekAlert!
Gas hydrate research: Advanced knowledge and new technologies
23.03.2018 | Helmholtz-Zentrum Potsdam - Deutsches GeoForschungsZentrum GFZ
New technologies and computing power to help strengthen population data
22.03.2018 | University of Southampton
Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.
The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
23.03.2018 | Event News
19.03.2018 | Event News
16.03.2018 | Event News
23.03.2018 | Materials Sciences
23.03.2018 | Agricultural and Forestry Science
23.03.2018 | Physics and Astronomy