Since 2010, the European Space Agency's CryoSat satellite has circled the Earth and monitored the state of the polar sea ice, along with the ice sheets that cover Antarctica and Greenland. Some of the data collected over the last six years has now been compiled into a one-of-a-kind 3D image, offering a more comprehensive look at Antarctic ice elevation than ever before.

The 3D image is constructed from around 250 million measurements taken by CryoSat's radar altimeter. Radar altimeters work by bouncing radio waves off the terrain below and measuring how long they take to return to the spacecraft. CryoSat has previously been used to detect sea ice loss in the Antarctic, along with helping to construct maps of the ocean floor.

In this instance, it was used to gauge the tiny variations in ice height across the entire Antarctic continent. This was helped by CryoSat's orbit, which carries it to latitudes within 200 km (124 mi) of the north and south poles, closer than any other Earth observation satellite.

"We used around 250 million measurements taken by CryoSat between 2010 and 2016 to create the most comprehensive picture of Antarctic ice elevation currently available," said Tom Slater, researcher at the UK Centre for Polar Observation and Modelling (CPOM).

With this clearer picture of ice over the Antarctic, the ESA says scientists will now be able to better distinguish between changes in topography and ice motion. It could, for example, help to inform calculations of how much the ice sheet is growing through the accumulation of snow and how much it is losing through melting ice. It will be used to track changes in ice thickness and could also be used to better plan fieldwork in the region.

"It's now widely recognized that dwindling polar ice is one of the first casualties of climate change, but it's important to provide the hard facts, and this we can do with CryoSat," said ESA's CryoSat mission manager, Tommaso Parrinello. "It's equally important to make sure the satellite's data are correct and so we have a huge international field campaign just started in the Arctic to take 'ground truth' measurements from aircraft and on the ice to compare with those of CryoSat."

The team will be making the model freely available so anyone with a scientific interest in the ice coverage over Antarctica can tap into its data.

"We want the digital elevation model to be accessible to anyone who uses ice-sheet surface topography measurements in their work," says CPOM Director Andrew Shepherd. "This should benefit not only studies of the Antarctic ice sheet, but also projections of future sea-level rise."

Source: ESA

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