Greenland Canyon Discovered with CReSIS Data


By Bill Daehler
Fall 2013

In late August, researchers from the UK, Canada, and Italy announced via a study published in Sciencethe discovery of an enormous canyon hidden beneath the Greenland ice sheet since before the dawn of mankind. Approximately 80% of the data in the study were collected by CReSIS instruments on NASA Operation IceBridge missions between 2009 and 2012.

“The dimensions of the Greenland canyon are comparable with parts of the Grand Canyon in the United States in terms of width and length and, in its deepest region, are about half of the Grand Canyon’s depth,” writes Jonathan Bamber, lead author of the study and a professor of physical geography at the University of Bristol.

In the study, Paleofluvial Mega-Canyon Beneath the Central Greenland Ice Sheet, the authors detail the remarkable size of the canyon, its role in transporting sub-glacial melt water today, and how it was likely created millions of years ago. The study was co-authored by Martin Siegert and Jennifer Griggs of the University of Bristol, Shawn Marshall of the University of Calgary, and Giorgio Spada of Urbino University in Urbino, Italy.

According to the study, parts of the hidden canyon plunge as deep as 800 meters (2,600 feet). It is at least 750 kilometers (460 miles) long—that’s longer than the Grand Canyon. The canyon runs from approximately the middle of Greenland to Petermann Glacier, which is located in northwest Greenland. The researchers were able to map out many features of the canyon with radar data made possible by CReSIS.

Greenland Canyon

Image 1: Visualization of the Greenland canyon’s topographical features. Image courtesy of NASA's Goddard Space Flight Center.

Topographic features of the canyon were discovered in large part thanks to the CReSIS Multichannel Coherent Radar Depth Sounder (MCoRDS), which is routinely deployed on IceBridge missions. The MCoRDS has a frequency range of 140 to 230 MHz and was developed by CReSIS for airborne sounding and imaging—specifically for surveying ice sheets. This instrument provides researchers details about the thickness of ice and features of the bedrock below by measuring the amount of time it takes for radar waves to move through the ice and reflect off the bedrock.

Operation IceBridge is a six-year NASA mission to survey the Earth’s polar regions with annual airborne missions. It will provide scientists with yearly data on rapidly changing ice sheets, ice shelves and sea ice in the Arctic and Antarctic.

Petermann Glacier

Image 2: A calving front of the Petermann Glacier in Northern Greenland. Image courtesy of Michael Studinger, NASA.

The authors hypothesized that the canyon plays a key role in moving sub-glacial melt water from beneath the Greenland ice sheet toward the end of ice sheet and out into the ocean. This, according to the authors, acts more like a river than glacially eroded bedrock:

“Indeed, none of the profiles are typical of glacially eroded valleys. The canyon follows a meandering path more typical of a large river system.”

This suggests that more than four million years ago, before the presence of the ice sheet, the canyon was a river system that moved water out from the Greenland interior and toward the ocean.

CReSIS will join the next IceBridge mission to Greenland in the Spring of 2014 to continue collecting data over Arctic ice. IceBridge will deploy to the Antarctic in late 2013 and, for the first time, will base flights out of Antarctica instead of Southern Chile.