Most accurate map of Antarctic ice streams

New map shows ice movements ten times more accurate and far more comprehensive than previous ones

While glaciers near the coast, such as the Ferrar glacier, are relatively well mapped, this does not apply to the Antarctic interior. Now, a new map shows ice movements much more precisely than before. © Eli Duke / CC-by-sa 2.0
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New look at the eternal ice: researchers have mapped the movements of the ice in the Antarctic as accurately as never before. Based on data from six satellites, their new map accurately tracks ice flow from 80 percent of the continent to 20 centimeters per year - ten times more accurate than any previous mapping. Thus, the new Antarctica map provides a better basis, especially for climate research.

Antarctica is the world's largest ice reservoir - and still one of the least explored continents. While the coastal glaciers, the Great Ice Shelf and the West Antarctic Peninsula are relatively well studied, this is not true for the eastern Antarctic and the icy interior of the Antarctic. Just 20 percent of the glaciers and ice masses there have been mapped in their movement so far.

Map of ice movements in the Antarctic. © Jeremie Mouginot / UCI

Six satellites and 25 years of data

This has changed now. Jeremie Mouginot of the University of California at Irvine and his team have now created a new map of Antarctic ice movements. It is based on 25 years of data from six satellites, including the ESA satellites ERS 1 and 2, as well as Envisat and the Canadian satellites Radarsat 1 and 2. By the researchers previous evaluation methods by a special interferometry a superimposition of several images - In addition, they were able to increase the precision of the measurements.

"Earlier mappings took advantage of so-called speckle and feature techniques optimized for high-speed areas of two to five meters per year, " Mouginot and his team explain. "But this limits our ability to determine the ice flow in the slow interior of the Antarctic." Phase-Interferometry combines data that the satellites have recorded at several angles at different angles. This makes it possible to detect even slow changes.

Quantum leap in resolution and coverage

The result is a map of Antarctica that covers more than 80 percent of the continent. It shows the speed of ice movements up to 20 centimeters per year exactly and is thus ten times more accurate than all previous mapping, as the researchers explain. "With this we have achieved a real quantum leap in the description of the ice flow in Antarctica, " says Mouginot. display

The new map delivers particularly great improvements in the slow-moving ice currents in the interior of the Antarctic. "In areas with slow movements of less than one meter per year, the precise coverage has now increased from 20 to 93 percent, " the researchers report. "This more detailed mapping will help us better understand the ice behavior under climate stress in a larger part of the continent than before."

Valuable information about the behavior of the ice sheet

Above all, the new map helps to elucidate the stability and structure of the Antarctic ice sheet. Because the boundaries and movements of the glaciers in the interior of the Antarctic are decisive factors influencing the behavior of the entire Antarctic ice cap. At the same time, the ice movements provide valuable information on what is hidden under the kilometer-thick ice.

"With this degree of precision in the inner regions, we can reconstruct high-resolution details of subsurface topography in much larger areas than before, " explains Mouginot's colleague Eric Rignot. "This is essential to improve our ice sheet models and Antarctic sea level forecasting." (Geophysical Research Letters 2019; doi: 10.1029 / 2019GL083826)

Source: University of California, Irvine

- Nadja Podbregar