Professor invents computer model

August 29, 2000

Professor invents computer model

By RICHARD F. BELISLE / Staff Writer, Waynesboro

MONT ALTO, Pa. - Sometime in the next five to six years, NASA will launch a satellite into orbit that will carry a device to measure salt levels in the oceans any place on the globe.

The device is called a Dicke radiometer. Perry Wood, an assistant professor of electrical engineering at Penn State Mont Alto, spent the summer developing a computer model of the device. The actual radiometer will be fashioned after Wood's model

Wood, 41, of Gettysburg, Pa., spent 10 weeks at the Goddard Space Flight Center this summer developing his model.

Wood and 24 other scientists from around the country were selected to work at Goddard in the Summer Faculty Fellowship Program, a research program sponsored by the American Society of Engineering Educators.

Not only did he get to work with Goddard scientists, the experience moved him several steps toward his goal of getting tenure at Penn State. Wood, an assistant professor, has taught at Mont Alto for three years.


He grew up in Gettysburg, graduated from Gettysburg College, earned his doctorate from the University of Virginia and still lives in Gettysburg.

He commuted daily from there to Goddard, a one-way drive of nearly two hours. "I didn't want to stay down there all summer," he said.

Wood will continue to work on the radiometer computer model at school during the fall semester. Because it's computer-based, he won't need lab facilities to get it done, he said.

The project has to be complete by January when he lectures on it at the National Radio Science meeting at the University of Colorado at Boulder. He plans to write about the project in scholastic journals.

Wood has been interested in electronics since he tuned in his first ham radio set when he was 15. "That got me started down this path," he said.

The sole purpose of a radiometer is to measure salt density in the ocean. Density determines the reflectiveness of the ocean surface.

What Wood calls in his scientific jargon, "a perfect blackbody radiator," is a surface that absorbs all the light and energy that hits it.

"A mirror reflects any light and energy that comes its way while the ocean absorbs a lot of what hits it. The ocean is part way between a mirror and a perfect blackbody radiator," he said. "The more salt in the ocean the more reflective it becomes to microwaves and radiation.

The amount of power received by a radiometer indicates the density of the salt, he said.

Wood said the amount of salt in the ocean is constant. Conditions like rain or water entering the ocean from rivers and circulation patterns determine the salinity in a specific area, he said.

"The saltier the ocean the less water evaporates. That means less energy in the atmosphere to affect weather patterns," he said.

Today, scientists rely on strategically placed buoys that measure salinity through electronically charged water samples or planes equipped with radiometers to measure ocean salinity.

"The whole purpose of the new satellite is to step back from the earth to see more of and different parts of the ocean at the same time," Wood said.

"The salinity changes are very minor so we need a sensitive, stable receiver and that is not easy to develop," he said. "The Dicke radiometer will take signals off the surface and digitize them much like a CD digitizes music."

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