March 29, 2002

Contact: Eve Lamborn, ITTC, (785) 864-4776.

KU graduate student's radar will help monitor melting polar ice sheets

LAWRENCE -- A KU graduate student has developed radar that NASA soon will use in Greenland to help determine whether melting polar ice sheets are contributing to rising sea levels.

Pannirselvam Kanagartnam, graduate student from Malaysia, developed a high-resolution airborne radar that maps layers of glacial ice for his doctoral thesis project.

Sea levels have risen 15 centimeters in the past 100 years and could rise another 5 millimeters per year during the next century. This change would drastically affect coastal regions, where 60 percent of the world's population lives. Scientists think melting polar ice sheets are contributing to this rise, although they are unsure of the amount.

Kanagartnam's radar maps the annual snow layers within ice sheets so that scientists can see how quickly snow has been accumulating or melting away over the years. Each year, accumulated snow forms a new layer and compresses the snow below it, making each layer denser than the one above it.

The radar, which has an antenna mounted in the bomb bay of an airplane that flies over the vast ice sheets, sends a signal that penetrates more than 150 meters below the surface. Whenever a discontinuity in the ice density is discovered, a signal bounces back up to the plane.

Kanagartnam designed the system to collect the returned signals despite the plane's cruising speed of 120 meters per second. These data, combined with other measurements, will help scientists understand how the ice caps are contributing to the rise in sea levels.

"This is the first time we know of this type of radar being used on an aircraft and doing a wide sweep of measurements," Kanagartnam said.

Under current methods, scientists measure the ice layers by drilling ice cores and counting the levels, like looking at tree rings. Kanagartnam said the problem with that method was that each sample provided information about a single point on the ice, making it difficult to get a picture of the ice sheet as a whole.

With radar attached to an airplane, measurements can be made over a larger target, he said.

Prasad Gogineni, Deane E. Ackers distinguished professor of electrical engineering and Kanagartnam's faculty adviser, said Kanagartnam's project was funded by a highly competitive NASA fellowship that was part of an initiative to understand changes in ice-covered regions of the earth. These areas are very sensitive to global climate changes, Gogineni said.

This May, the radar will be used to gather data that will go straight into the models used to understand ice changes, said Waleed Abdalati, manager of the polar program at NASA headquarters in Washington, D.C.

"We'll be collecting data for a broad group of people to use," Abdalati said. "It's likely to become a frequently used instrument with a great contribution to glaciology in general."

Abdalati said the radar would provide a much more accurate picture of the ice sheets.

"We can cover hundreds and hundreds of kilometers and understand how much snow really has fallen and make far more accurate comparisons to estimates of what we're losing," he said.

Kanagartnam has been working on the radar since 1998 and making annual treks to the Greenland ice sheet for testing. Test flights last summer successfully mapped layers of the 3-kilometer-thick ice and proved that his concept worked. David Braaten, associate professor of physics and astronomy, helped Kanagartnam with geophysical interpretation of the data.