Researchers at the Center for Remote Sensing of Ice Sheets based at the University of Kansas have unlocked important new details below the ice in key areas of Greenland and Antarctica that will reshape how scientists forecast changes to sea level. Data collected through radar systems created at KU provide the first-ever detailed maps of the subsurface conditions on prominent and scientifically important glaciers on opposite sides of the Earth.
The CReSIS team successfully gathered data on the depth, topography and conditions at the base of two glaciers that are critical to monitoring and predicting sea level rise, Jakobshavn Glacier in west Greenland and Byrd Glacier in east Antarctica. CReSIS’s findings are published online as the lead article in the September issue of the Journal of Glaciology, the world’s leading publication on the study of ice and natural phenomena that involve ice.
“Bed topography is very important to understanding and modeling of speedup of glaciers like Jakobshavn,” said Prasad Gogineni, distinguished professor in the KU School of Engineering and director of CReSIS. “Models that accurately represent the processes causing this speedup of fast-flowing glaciers are essential to predicting the behavior of ice sheets in a warming climate.”
Jakobshavn Glacier is the fastest flowing glacier on Earth and drains about 7.5 percent of Greenland’s ice. It’s approximately one-third as wide as the Grand Canyon, but just as deep, and Jakobshavn is about one mile below sea level at its deepest point. Byrd Glacier is one of the most confined Antarctic ice streams and in recent years has been flowing about 15 percent faster than its historical average. The glaciers have several characteristics in common, such as the discharge of large amounts of land-based ice into the sea, channels with extremely deep beds, and rough, crevassed surfaces.
At Byrd Glacier, CReSIS researchers discovered a sub-glacial trench approximately 1.8 miles below sea level. The CReSIS team also revealed that data collected in the late 1970s on Byrd Glacier’s depth, which served as the basis for all computations on the ice sheet’s behavior, were off by more than half a mile in some areas. That means computer models now need a complete overhaul due to the very different bed topography discovered by CReSIS researchers.
“Gathering data to construct these maps is extremely challenging for glaciers like Jakobshavn because they contain warm ice near the bed and their surfaces are very rough due to crevassing. The signal from the ice bed, already weak due to the warm temperature of the ice near the bed, is often also masked by signals reflected by the rough ice surface; this is known as surface clutter. It takes extremely high-sensitivity radars to capture the weak signal and advanced post-processing to extract it from the surface clutter,” Gogineni said.
CReSIS collaborated with the University of Arkansas on image processing of radar echograms to bring out weak echoes.
“Without long-term support from the National Science Foundation and NASA to improve radars and develop techniques to extract information, CReSIS could not have sounded Jakobshavn and other key glaciers,” Gogineni said.
Established by the NSF Division of Polar Programs in 2005, CReSIS has made great strides in research and fieldwork concerning changes in ice sheets and their effect on sea level rise. The Center has been a key participant in NASA’s Operation Ice Bridge, which is the largest airborne survey of Earth’s polar ice ever flown.
KU serves as the lead institution of CReSIS, which is composed of six additional partner institutions: Elizabeth City State University, Indiana University, the University of Washington, The Pennsylvania State University, Los Alamos National Laboratory, and the Association of Computer and Information Science Engineering Departments at Minority Institutions. CReSIS researchers collaborate with scientists, engineers and institutions around the world.