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Scientists conduct survey.
Photo Credit: Dan Dixon
ITASE scientist Gordon Hamilton, left, takes a survey reading to determine the rate of snow accumulation on the East Antarctic ice sheet during an overland traverse during the 2006-07 austral summer season.

Down to the core

Gordon Hamilton is another ITASE member with previous Antarctic field experience in the program. A research associate professor at the Climate Change Institute, Hamilton studies the topography of the ice sheet to understand how it affects the speed of the wind across the surface, a factor in the transportation and accumulation of snow. He also uses high-precision GPS to create a detailed map of the sampling areas.

“For understanding the ice core record, we have to know what the surface slope is from where the cores are [taken],” Hamilton explained.

In a related ITASE project, Hamilton revisited previous traverse sampling sites near the WAIS Divide field camp in West Antarctica with graduate student Leigh Stearns. The surveys will help the researchers calculate ice flow velocities and determine rates of ice sheet thickness change.

Another one of Hamilton’s research goals is to understand the contribution of ice sheet melt to sea level rise. Satellite imagery can determine thickness but not density, hence the need for the ice cores.

His graduate student, physicist Dan Breton, built an ice core density analyzer that the team uses to image the ice cores during the traverse.

The density gauge uses low-energy gamma rays to determine the ice density, not unlike a bone density scan that uses X-rays to determine density by the absorption of the beam. Each density test on a one-meter-long sample can take upwards of 45 minutes to complete.

The first-year Ph.D. student said he had a relatively short time to assemble the instrument and looks forward to making some tweaks before next year’s field season, which is scheduled to end at South Pole.

“It’s really been a scramble to design it, engineer it, fix everything that didn’t work and get it ready to go,” he said of the homemade density analyzer.

This was Breton’s first season in Antarctica. Expecting temperatures on the polar plateau in at least the negative 40 degrees Celsius range, he built a large, insulated wood box to hold all of the electronics for the density analyzer. It turned out the austral summer was not so harsh, and Breton’s equipment overheated. He had to drill holes in the box to provide ventilation.

“Until you have a firsthand knowledge of what it’s really like [here],” he noted, “it’s difficult to design instrumentation that’s really fit for what you’re doing.”

Down for next season

Andrei Kubatov said that ITASE is not only a unique platform for science but an excellent opportunity for teaching young scientists in the field.

“It’s very important,” said Kutabov, a research assistant professor with the Climate Change Institute whose work revolves around how volcanic eruptions force climate change.

Mayewski likened the experience to an apprenticeship. “We like to think we’re producing field savvy scientists who can take care of themselves really well in these extreme environments and understand how to have a good time and do a lot of good science,” he said.

For Koenig, the University of Washington graduate student, the traverse got her out from behind a com¬puter screen and into an environment where “every day was different.”

“I usually look at ice sheets from a satellite,” she said.

More Information

Next year, the ITASE team will have to cover far more ground to reach the South Pole from where it left its equipment and vehicles. Several other countries are also doing ITASE traverses next year in conjunction with the International Polar Year, according to Mayewski.

“There’s plenty more to learn in East Antarctica,” Mayewski said. “Every year the program gets better and better.”

NSF-funded research in this story: Paul Mayewski and Gordon Hamilton, Climate Change Institute at University of Maine. 

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