Post 8478
These Stunning 3D Images Reveal How a Massive Greenland Glacier Has Changed
Watching a glacier
Credit: Jefferson Beck/NASA Goddard
NASA scientists are keeping sharp eyes on Greenland’s glaciers. Such gazing reveals more than the beauty of this unique and massive, icy island. The scientists, part of NASA’s Operation IceBridge, are conducting airborne surveys to find out how the glaciers are changing over time.
Glacier surface
Credit: Jefferson Beck/NASA Goddard
Laser altimeters can map the teensy details of the surfaces of these Greenland glaciers. NASA uses two laser altimeters: One is optimized for low altitude and the other for medium altitude, they said.
Laser altimetry
Credit: Jefferson Beck/NASA Goddard
The laser altimeter measurements show elevation changes on the glacier surface.
Helheim Glacier
Credit: Jefferson Beck/NASA Goddard
“On Greenland’s rugged eastern coast, spilling into a mountainous fjord, lies the 4-mile-wide Helheim Glacier, named for the Viking world of the dead,” NASA says in the video.
Dramatic changes
Credit: Jefferson Beck/NASA Goddard
“Flights spanning two decades reveal the dramatic changes that have taken place,” NASA said on a video about the mission.
Rapid retreat
Credit: Jefferson Beck/NASA Goddard
Here, the glacier is shown after a rapid retreat and thinning episode.
Partial recovery
Credit: Jefferson Beck/NASA Goddard
Following the retreat, the glacier partially recovered its former extent.
Helheim in 2001
Credit: Jefferson Beck/NASA Goddard
NASA missions have flown along the center line of the glacier year after year. Here, the extent of the Helheim Glacier is shown in 2001 from NASA Operation IceBridge surveys.
Helheim in 2007
Credit: Jefferson Beck/NASA Goddard
The extent of the Helheim Glacier is shown in 2007 from NASA Operation IceBridge surveys.
Helheim extent
Credit: Jefferson Beck/NASA Goddard
The extent of the Helheim Glacier is shown in 2011 from NASA Operation IceBridge surveys.
Helheim in 2014
Credit: Jefferson Beck/NASA Goddard
The extent of the Helheim Glacier is shown in 2014 from NASA Operation IceBridge surveys.
Firing laser pulses
Credit: Jefferson Beck/NASA Goddard
With laser altimetry, laser instruments on board the research aircraft fire several thousand pulses of light every second. The results reveal the height of the surface below.
Spinning swath
Credit: Jefferson Beck/NASA Goddard
The lasers spin in a circle that’s 820 feet (250 meters) across, which provides a swath of data that an be transformed into a topographic map of the ice, NASA said.
Elevation changes
Credit: Jefferson Beck/NASA Goddard
Here, higher elevations on the glacier are shown in red and orange, while lower elevations are in green and blue.
1998 calving event
Credit: Jefferson Beck/NASA Goddard
The laser altimeters showed height measurements all the way down to the Helheim Glacier’s calving front, where icebergs break off into the sea.
Icebergs break off
Credit: Jefferson Beck/NASA Goddard
Here’s a 1998 swath compared with one from 2013. In this image, the color scale is changed to show the local differences in elevation, according to NASA.
Retreat
Credit: Jefferson Beck/NASA Goddard
The 2013 swath from the laser altimeters reveals that the calving front retreated significantly since 1998, by 2.5 miles (4 kilometers), according to the NASA video.
Gorgeous mosaic
Credit: Jefferson Beck/NASA Goddard
NASA’s Operation IceBridge mission has also used a high-resolution camera system to take overlapping images of the ice of Helheim Glacier throughout its 8-hour flights. These images can then be pieced together into a mosaic.
Stereoscopic view
Credit: Jefferson Beck/NASA Goddard
Because the images overlap, they can provide scientists with a stereoscopic view of the ice and even elevation measurements. The NASA scientists overlaid the elevation information from the images on top of the measurements from the laser altimetry.
Steep calving front
Credit: Jefferson Beck/NASA Goddard
Helheim’s calving front, which is 70 feet (21 meters) high, can be seen here.
Springtime flights
Credit: Jefferson Beck/NASA Goddard
Until the launch of a new NASA satellite called ICESat-2, the Operation IceBridge mission will return to Greenland every spring to continue monitoring the glacier, NASA said.
