The loss of Antarctic ice as seen in听Landsat images. (Credit: NASA Earth Observatory)
This story was adapted from one published by NASA's Goddard Space Flight Center. .
New time-lapse videos of Earth鈥檚 glaciers and ice sheets as seen from space鈥攕ome spanning nearly 50 years鈥攁re providing scientists with new insights into how the planet鈥檚 frozen regions are changing.听
At a media briefing Dec. 9 at the in San Francisco, scientists released new time series of images of Alaska, Greenland, and Antarctica using data from satellites including the .
A section of the West Antarctic Ice Sheet as seen from space in visible (left) and microwave (right) light. Two subsurface lakes show up as dark patches in the microwave images. (Credit: ESA)
精品SM在线影片鈥檚 Devon Dunmire hidden below the surface of Antarctica鈥攆eatures that, she said, could have huge influences on the future of polar ice sheets.听
鈥淢eltwater impacts ice shelf stability but we don't necessarily know the distribution of all meltwater across Antarctica because some is located beneath the surface in subsurface lakes,鈥� said Dunmire, a graduate student in the Department of Atmospheric and Oceanic Sciences. 鈥淲e won't have a complete grasp on how meltwater impacts Antarctic ice shelves until we understand the volume and location of subsurface lakes.鈥�
Other research highlighted at the media briefing included a series of images that illustrate the dramatic changes of Alaska鈥檚 glaciers and could warn of future retreat of the Hubbard Glacier. Over Greenland, different satellite records show a speed-up of glacial retreat starting in 2000, as well as meltwater ponds spreading to higher elevations in the last decade, which could potentially speed up ice flow.听
The Landsat satellites have provided the longest continuous record of Earth from space.听
But it doesn鈥檛 always take decades worth of data to study polar features鈥攕ometimes just a year or two will provide insights. The Antarctic ice sheet experiences surface melt, but there are also lakes several meters below the surface, insulated by layers of snow.听
To see where these subsurface lakes are, Dunmire used microwave radar images from the satellite. Snow and ice are basically invisible to microwave radiation, but liquid water strongly absorbs it.
Dunmire鈥檚 new study, presented at the AGU meeting, found lakes dotting the George VI and Wilkins ice shelves near the Antarctic Peninsula鈥攅ven a few that remained liquid throughout the winter months. These hidden lakes might be more common than scientists had thought, she said, noting that she is continuing to look for similar features across the continent鈥檚 ice shelves.
For more information on Landsat and the upcoming Landsat 9 mission, visit: or .
