Led by Carolyn Merry, professor of civil engineering at Ohio State, the researchers have mapped potential routes across a stretch of the Ross Ice Shelf, one of the giant ice sheets that extends outward from the frozen continent. Merry's group reported the work in a recent issue of the journal Cold Regions Science and Technology.
The routes start at the McMurdo Station, the main entryway to Antarctica - some 850 miles from the South Pole - and head towards the Leverett Glacier in the Transantarctic mountains. Overland travel across the stretch of the ice shelf between McMurdo and the glacier is fraught with dangers because of deep crevasses that lie hidden under snow. Past this corridor, beyond the ice shelf to the South Pole, lies a decidedly safer terrain.
In 1991, a tractor traveling across the ice shelf -- a thick layer of ice floating upon the Ross Sea - fell into a crevasse, bringing home the risks associated with surface transport from McMurdo to the interior of Antarctica. That's one of the reasons why supplies to the U.S. station at the South Pole are transported entirely by aircraft.
But overland travel could be more economical and convenient than air transport. "There is only a limited amount of materials that you can put on a C-130," Merry said, referring to the type of aircraft used for transporting goods. "With tractor trailers, you could transport a large volume of supplies in a single trip."
Merry and her colleagues analyzed satellite images of the area to identify potential travel routes through the corridor. Using software, the researchers enhanced the images and were able to locate crevasses in the ice shelf. The crevasses - deep cracks in the ice layer - showed up in the images as shadow lines on a white sheet.
"These crevasses are very hard to see from the ground and even from a low-flying airplane because a lot of them are bridged over by snow that drifts into them," Merry said.
Based on the images, the researchers came up with safe routes through the corridor. The next step, Merry said, would be to confirm the safety of the suggested routes through surveys on the ground using radar technology. "Having a preliminary route to work with would save time and money on follow-up ground surveys," Merry said.
Merry and her colleagues, including the late Ian M. Whillans, professor of geological sciences at Ohio State and lead author of the study, used the satellite images for another, more fundamental purpose - to measure the rate of movement of ice sheets in the region. These ice sheets slide northward every year, slowly melting into the ocean.
Comparing images of the Ross Ice Shelf taken in 1989 and in 1994, the researchers found that most of the ice streams flowing along the shelf were moving at about 200 meters per year. The observation confirms previous field measurements that used less reliable techniques.
"What we have learned is there are some parts of the ice shelf that are moving faster than other parts," Merry said. "Although most of our observations confirm previous findings, we have added additional velocity measurements in the site that we never had before."
The research was funded by a grant from the National Science Foundation.
Written by: Yudhijit Bhattacharjee, 614-292-8456, bhattacharjee.5@osu.edu
Journal
Cold Regions Science and Technology