UW News

December 14, 2018

UW glaciologist gets first look at NASA’s new measurements of ice sheet elevation

UW News

Antarctic map and blue line

The horizontal blue line is the travel path for ICESat-2. The lower line shows some of its first measurements. This satellite can capture steep terrain and measure elevation much more precisely than its predecessor.NASA's Earth Observatory/Joshua Stevens

Less than three months into its mission, NASA’s Ice, Cloud and land Elevation Satellite-2, or ICESat-2, is already exceeding scientists’ expectations, according to the space agency. The satellite is measuring the height of sea ice to within an inch, tracing the terrain of previously unmapped Antarctic valleys and measuring other interesting features in our planet’s elevation.


Ben Smith

Benjamin Smith, a glaciologist with the University of Washington and member of the ICESat-2 science team, shared the first look at the satellite’s performance at the American Geophysical Union’s annual meeting Dec. 11 in Washington, D.C.

Mountain valleys “have been really difficult targets for altimeters in the past, which have often used radar instead of lasers and they tend to show you just a big lump where the mountains are,” Smith told the BBC. “But we can see very steeply sloping surfaces; we can see valley glaciers; we’ll be able to make out very small details.”

With each pass of the ICESat-2 satellite, the mission is adding to the data sets that track Earth’s rapidly changing ice. Researchers are ready to use the information to study sea level rise resulting from melting ice sheets and glaciers, and to improve sea ice and climate forecasts.

Watch Smith at the AGU press conference

Hear Smith talk about ICESat-2

In topographic maps of the Transantarctic Mountains, which divide east and west Antarctica, there are places where other satellites cannot see, Smith said. Some instruments don’t orbit that far south, while others only pick up large features or the highest points and so miss minor peaks and valleys. Since launching ICESat-2, in the past three months scientists have started to fill in those details.

“It’s spectacular terrain,” Smith said. “We’re able to measure slopes that are steeper than 45 degrees, and maybe even more, all through this mountain range.”

As ICESat-2 orbits over Antarctica, the photons reflect from the surface and show high ice plateaus, crevasses in the ice 65 feet (20 meters) deep, and the sharp edges of ice shelves dropping into the ocean. These first measurements can help fill in the gaps of Antarctic maps, Smith said, but the key science of the ICESat-2 mission is yet to come. As researchers refine knowledge of where the instrument is pointing, they can start to measure the rise or fall of ice sheets and glaciers.

Early data suggest that Antarctica’s Dotson ice shelf has lost more than 390 feet (120 meters) in thickness since 2003, Smith told the Associated Press.

“Very soon, we’ll have measurements that we can compare to older measurements of surface elevation,” Smith said. “And after the satellite’s been up for a year, we’ll start to be able to watch the ice sheets change over the seasons.”

Mission managers expect to release the data to the public in early 2019.

The first ICESat satellite operated between 2003 and 2009. The more sophisticated ICESat-2 launched Sept. 15, 2018, from Vandenberg Air Force Base in California. Its laser instrument, called ATLAS (Advanced Topographic Laser Altimeter System), sends pulses of light to Earth. The instrument then times, to within a billionth of a second, how long it takes individual photons to return to the satellite. ATLAS has fired its laser more than 50 billion times since going live Sept. 30, and all the metrics from the instrument show it is working as it should, NASA scientists say. IceBridge, an aircraft-based NASA campaign, operated between the two satellite missions.


For more information, contact Smith at besmith@uw.edu or 206-616-9176.

Adapted from a NASA feature article.