Wednesday, August 17, 2011

Understanding climate change from the ground up

Electrical engineers install sensors at Matthaei Botanical Gardens to measure soil moisture

Planted at the U-M Matthaei Botanical Gardens right now are seeds to some answers to a major quandary in climate change prediction: How is moisture distributed throughout the Earth’s soils?

“Root zone soil moisture is one of the most important pieces of information for understanding how ecosystems function, and how the water, energy, and carbon cycles are regulated around the globe,” says Mahta Moghaddam, a professor in the Department of Electrical Engineering and Computer Science.

A NASA satellite called the Soil Moisture Active and Passive (SMAP) is scheduled to launch in 2014. Its mission will be to gather soil moisture data from above, eventually leading to global maps. In support of this project, Moghaddam and her colleagues are installing networks of wireless sensors on the ground in several test spots. The data from the sensors will be used to validate the satellite data—to help ensure that the orbiting instrument is giving accurate readings.

One of these test spots is here at Matthaei where electrical engineering researchers installed 30 wireless sensor nodes last month. Another is on a farm in Oklahoma. Both sites are giving the engineers valuable data and experience.

For Mingyan Liu, an associate professor in the Department of Electrical Engineering and Computer Science, they represent her first forays into fieldwork.

“The field experience is very different from working with pen and paper and a computer,” said Liu, an expert in wireless sensor network technology. “In the field we have to deal with practical and logistical issues that never would come up in a theoretical exercise.”

Issues like: How can we save our sensors from itchy cows?

On the Oklahoma site, the animals damaged many of the sensor systems by scratching their backs on the small solar panels that powered them.

Ph.D. student Agnelo Silva deployed two “go away, cow” techniques on his last trip to the farm earlier this summer. He is pictured at right installing one of them, which is a fence around the sensor. He’ll soon return to see if it worked.

The researchers’ technology is called SoilSCAPE, which stands for Soil moisture Sensing Controller And oPtimal Estimator. In addition to Moghaddam and Liu, U-M electrical engineering professor Demos Teneketzis and MIT civil and environmental engineering professor Dara Entekhabi are also involved in the research.

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