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Dave Billesbach's world is
In a State of Flux

At 6 a.m., Dave Billesbach is working hard. The sky is dark but the air is already warm and humid. The heat will be even worse where he’s going, and there’s not much to shield him from the sweltering temperatures. The summer wheat crop is up on the plains. This is one of the best times to go out in the field.

If there’s one thing he’s passionate about, it’s fieldwork. He loves the outdoors. Maybe it was the influence of his younger years in Central City, growing up close to virgin tallgrass prairies, riparian Cottonwood forests and open stretches of the meandering Platte River. He’s seen moose, eagles and gray wolves in Canada. One time a coyote walked across the field where he was working, paused to survey the territory, and trotted back down the road. He doesn’t expect these things to happen. They just do. The unexpected is the norm in the field. And you only have one chance to get it right.

Piece-by-piece, he carefully stows his instruments in the back of the van for the long drive ahead. He’s headed to a 160-acre research site near Billings, Okla. The equipment he’s packed is designed to measure carbon dioxide and water vapor in the atmosphere. In more precise language, it’s measuring carbon dioxide flux — the rate at which CO 2 flows to and from the atmosphere. Carbon dioxide is one of the “greenhouse” gases that contribute to global warming and other marked changes in atmospheric chemistry.

Gathering this data is usually a time-consuming, expensiveoperation that takes place over a period of months, even years at a time. Billesbach and his colleagues have developed a rapidly deployable, portable, and low-maintenance field measurement system that collects data for much shorter periods. The system may provide a viable alternative to the expensive equipment installed at most research sites.

Billesbach, assistant research professor, is working withscientists from Lawrence Berkeley National Laboratory and Stanford University on a three-year grant funded by the U.S. Department of Energy. Their work is a small piece of a bigger effort by the DOE to gather data to improve the general circulation models used for global climate research and prediction.

“We’re asking questions such as, do all wheat fields behave the same?” he says. “How do various land surfaces affect the carbon dioxide exchange between the land and the atmosphere?”

Billesbach has studied and conducted research in trace gas dynamics for more than 10 years. It’s a far cry from physics, the field in which he obtained his doctorate. He grew up in the labs of the physics department at the University of Nebraska and received his Ph.D. in 1987. He could still pass for a college student, even with his graying hair.

“I liked physics,” he says, “but it was often hard to see where the work was going. I like the kind of research I’m doing now. I’ve been doing this for so long,” he says, “that I think I can make a contribution to this field. This project has convinced me of that.”

If only he could spend more time out in the field. Instead, he spends many hours in his office, writing reports and papers, working on the computer, and doing all the tedious paperwork necessary to manage his projects. Half of his salary comes from research grants and contracts. “I’d like to continue with this work as long as there is funding,” he says, “but I don’t know what the future will hold.”

With luck (and hard work), he may spend the rest of his careerin this field. He probably won’t make any groundbreaking discoveries, but he has the satisfaction of knowing that his small project is part of something significant. “I’ve been able to make a career without having to build bombs,” he says. “I can see more societal benefits from this kind of research.”

The work is often painstakingly slow. Billesbach’s colleague, Shashi Verma, is a longtime researcher in this field. The two, along with faculty from electrical engineering, agronomy and chemistry, have studied methane and carbon dioxide flux in the Nebraska Sandhills and the boreal wetlands in Saskatchewan.

“There’s been a lot of focus in the past on measuring carbondioxide flux from forests, thinking that’s where the gas was sequestered,” says Billesbach. “Now the thinking is that agricultural land and prairies are important, too.”

About 10 years ago, the DOE established the first of threefield measurement sites in a 55,000-square-mile region in north-central Oklahoma and south-central Kansas. The other two Atmospheric Radiation Measurement (ARM) program sites are in northern Alaska and the western Pacific. Each site has in-situ instruments and remote sensing instruments arrayed across the entire area to capture climate data. The Southern Great Plains site is ideal for a number of reasons. It’s cold and dry in the winter and hot and muggy in the summer. You get several climates for the price of one.

Billesbach arrives at the site on schedule and parks the van. It will take two to three hours to unload and set up the instruments. Portable measurement systems have been done before, he says, but not quite this portable. This system uses 30 to 35 watts of 12-volt DC power, which can be generated by solar panels and storage batteries. “We can go to undeveloped, remote sites where there is no line power,” he says. “This was very hard to do in the past.”

The instruments go up next to a 60-meter tower that’s been gathering data for a couple of years. “There’s a large area in range from the top of that tower, but remember,” he says, “we’re not looking at one big wheat field.”

Before the end of the week, the project team will set up another two portable systems in different quarter sections of the wheat field. All use the scientifically well-established eddy covariance technique to calculate CO 2 fluxes by measuring vertical wind velocity and fluctuations of atmospheric CO 2 density. Billesbach hopes the data will help validate results from other data collection efforts and lead to improved computer models in climate research. He talks about the problems of modeling from big data sets collected over a number of years. “You can’t do these comparisons in isolation.”

The tripod towers unfold easily. He mounts the instruments tothe two towers and hooks up the cables. Then he hooks the instrumentation up to a laptop computer enclosed in a 2x2 ventilation box. The towers sit about 12 to 13 feet above ground and hold a sensor that he jokingly describes as looking “like a pop can with a golf ball on top.” In fact, it’s an LI-7500 open path gas analyzer, the latest and best on the market and home grown in Nebraska by Li-Cor.

The team will set up their portable equipment for one week at a time in six different quarter sections of a wheat field. “One week is a typical operational period,” Billesbach says. “But it’s hard to define parameters on this. It depends on the time of year, and we’re at the mercy of the weather.”

He plants a few sensors in the soil to measure how much solar energy is going into the ground. He gives everything a last check and starts the data-logging program. The data stream will be analyzed back in the office and eventually end up at a designated repository or archive.

Twelve hours after he started, his work is done for the day. Now it’s best to leave everything alone. “I check in once a day to make sure everything is running,” he says, “but I like to keep hands off as much as possible. We’re after undisturbed records.” That’s being optimistic. Today was a scorcher. No relief tomorrow, either. But there’s talk of rain on Wednesday or Thursday.

He takes off his cap, wipes the sweat from his forehead, and walks toward the van. A cold drink would sure taste good.


-- Deb Derrick

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