The flow of Antarctic ice, derived from feature tracking of Landsat imagery. Credit: NASA Earth Observatory
Using a new computer method, researchers have begun to piece together the flow of Antarctic ice over the last decade.
NASA researchers used a new computer-vision technique to crunch satellite data, providing a clearer picture of changes in Antarctic ice flow into the ocean. The technique crunched data from hundreds of thousands of NASA-U.S. Geological Survey Landsat satellite images to produce a high-precision snapshot of the changes in the ice-sheet motion, enabling researchers to look for subtle changes.
“When I began working on this project three years ago, there was a single map of ice sheet flow that was made using data collected over 10 years, and it was revolutionary when it was published back in 2011,” cryospheric researcher Alex Gardner of NASA’s Jet Propulsion Laboratory and the study’s lead author, said in a statement. “Now we can map ice flow over nearly the entire continent, every year.
“With these new data, we can begin to unravel the mechanisms by which the ice flow is speeding up or slowing down in response to changing environmental conditions,” he added. “We’re applying computer vision techniques that allow us to rapidly search for matching features between two images, revealing complex patterns of surface motion.”
In all, the study found an overall ice discharge for the Antarctic continent of 1,929 gigatons per year in 2015, with an uncertainty of plus or minus 40 gigatons, representing a 36-gigaton increase annually, plus or minus 15 gigatons.
The researchers found that between 2008 and 2015, the East Antarctic Ice Sheet had essentially no change in its rate of ice discharge—ice flow into the ocean. They also confirmed that the flow of West Antarctica’s Thwaites and Pine Island glaciers into the ocean continues to accelerate, albeit at a slower rate.
The study confirmed that ice flow from West Antarctica–the Amundsen Sea sector, the Getz Ice Shelf and Marguerite Bay on the western Antarctic Peninsula– accounted for 89 percent of the increase.
The researchers found that a previously unmeasured acceleration of glacier flow into Antarctica’s Getz Ice Shelf on the southwestern part of the continent is likely a result of ice-shelf thinning.
The glaciers feeding Marguerite Bay on the western Antarctic Peninsula, increased their rate of flow by 1,300 to 2,600 feet per year, likely due to ocean warming.
The new research also provides a baseline for future measurements of Antarctic ice changes and can be used to validate numerical ice sheet models that are needed to make projections of sea level. It also opens the door to faster processing of massive amounts of data.
“We’ll be able to use this information to target field campaigns, and understand the processes causing these changes,” Gardner said. “Over the next decade, all this is going to lead to rapid improvement in our knowledge of how ice sheets respond to changes in ocean and atmospheric conditions, knowledge that will ultimately help to inform projections of sea level change.”
