UM-Led Study Looks For Climate Change Insight

A new $26 million NASA project led by a University of Michigan researcher aims to help clarify how ecosystems exchange carbon with the atmosphere, an important piece of missing knowledge in the quest to understand and predict climate change.

The project's goal is to help determine whether the North American continent is a net source or sink of carbon. Researchers from UM, NASA, Harvard, MIT, Oregon State, and Purdue are participating.

Over the next five years, a radar instrument called the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) will measure root zone soil moisture in nine North American regions from aboard a Gulfstream-III aircraft. The radar can penetrate up to four feet beneath the ground surface.

Root-zone soil moisture levels show how well a plant is functioning, said principal investigator Mahta Moghaddam, an associate professor in the Department of Electrical Engineering and Computer Science.

"Even your houseplant has its own net exchange of carbon," Moghaddam said. "It takes carbon dioxide in during the day and breathes out oxygen at night and how much it produces has to do with how much water you're giving it."

Scientists don't understand exactly when and where this carbon exchange process is most efficient. Questions about root zone soil moisture are believed to contribute 60-80 percent of the uncertainty about how the ecosystem exchanges carbon with the atmosphere. Collaborating researchers will plug Moghaddam's moisture measurements into models to produce a continental estimate of the net ecosystem exchange. That number, which will show whether the continent takes in or releases more carbon, is expected to be available in May 2015.

Moghaddam designed the AirMOSS instrument, a table-top-sized, high-powered, low-frequency radar. She also developed computational techniques to analyze the signals it sends back.

"This work will help us understand the human carbon footprint," Moghaddam said. "We know it's big, but we don't know how fast it's changing or how big it's going to get. Today, we rely on estimates and there is huge uncertainty."

Beyond this project, Moghaddam envisions other applications for this radar instrument, including surveillance.

More at www.engin.umich.edu.

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