Ohio State researchers receive NASA grant to test deep-ice temperatures

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Researchers at The Ohio State University are leading a project to develop technology that can determine temperatures deep under Greenland’s ice sheet from airplanes – or even potentially from spacecraft.

The data resulting from the use of this specially designed microwave radiometer could provide a glimpse into the potential impacts of climate warming on sea levels in the world’s oceans.

“The ice sheets of Greenland and Antarctica play an important role in the global climate,” said Professor Joel Johnson of Ohio State’s Department of Electrical and Computer Engineering and the project’s primary investigator. “They contain about 70 percent of the world’s fresh water, and gauging temperatures deep beneath their surface is a critical way to predict how they might evolve in the future.”

The research is being funded by a $3 million, three-year grant from NASA’s Science Mission Directorate as part of its Instrument Incubator Program (IIP-13) in support of its Earth Science Division. IIP-13 will provide funds to develop instruments and instrument subsystems that will enable future Earth science measurements and visionary concepts.

Johnson will lead a multidisciplinary, multi-university team of researchers working on the project titled “UWBRAD: Ultra Wideband Software Defined Microwave Radiometer for Ice Sheet Subsurface Temperature Sensing.”

“The data we collect will enhance the research community’s ability to determine how ice deforms internally and how quickly an ice sheet flows across its base,” Johnson said. “It also will help us compile mean annual temperatures and monitor climate change.”

Professor Ken Jezek, a glaciology expert with The Ohio State University Byrd Polar Research Center, said using radiometers to record naturally occurring microwaves would be vastly more efficient than current techniques.

“Presently, our only direct knowledge of ice sheet internal temperature is from measurements in boreholes,” Jezek said. “But boreholes to the base of the ice are few across the expanses of Greenland and Antarctica.”

Building a microwave radiometer that can be used to perform ice sheet thermometry from an airplane or even a spacecraft would be faster, cheaper and allow for readings over much greater geographic areas.  This concept is routinely used to measure temperature in the atmosphere, but has never been applied to ice, Jezek said. 

Johnson will design a specialized microwave radiometer that will receive the naturally occurring low-frequency microwaves given off by the ice sheets. Because microwaves at different frequencies carry information about different depths in the ice sheet, Johnson said it should be possible to determine the temperature of ice hundreds of meters below the surface without boring holes. The envisioned microwave radiometer should be able to get the same information from an airplane flying over the ice sheets.

“These ice sheets are a mile thick,” Johnson said. “It’s hard to know what their temperatures are without extensive drilling. And these temperatures matter.”

The colder the ice is, the stiffer it is. The warmer the ice, the faster it will flow.  Consequently, knowing the temperature of the ice at different depths is central to modeling ice sheet behavior.

Johnson said this is crucial information for evaluating climate change. Current models predict that sea levels should rise by around one meter by the year 2100. Such an increase would have significant impacts on coastal communities, ocean temperatures and global weather; however, these forecasts are based on the limited information currently available on ice sheet internal temperatures.

“There is presently great interest in predicting the changing discharge rate of ice from Greenland and Antarctica into the oceans,” Jezek said. “Current predictions are based on sophisticated models that include estimates of ice flow rate. Because temperature is a controlling factor on flow rate, improving measurements of glacier internal temperature will substantially improve those model predictions.”

The technology also has the potential to help researchers measure deep-surface soil moisture levels and snow thickness, which have a variety of applications.

Other members of the team are:

  • Professor Mike Durand of the Ohio State School of Earth Sciences, Professor Leung Tsang of the University of Washington ECE department, and Dr. Giovanni Macelloni of the National Research Council in Italy, all of whom are experts is modeling radiometer measurements of ice sheets;
  • Professor Chi-Chih Chen of the Ohio State ElectroScience Laboratory (ESL) in the Department of Electrical and Computer Engineering , who will be developing the antenna for the system;
  • Three Ohio State graduate students (two from the ESL and one from Earth Sciences); and
  • One senior research associate from the ESL, who will perform instrument development and testing.

Ohio State’s proposal was one of 17 grants that received a total $71 million from NASA’s Earth Science Technology Office. The goals of IIP are to “research, develop and demonstrate new measurement technologies that enable new Earth observation measurements and reduce the risk, cost, size, volume, mass and development time of Earth observing instruments.”

Related story: Operation Icebridge measurements may be used in this research.

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