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Civil and Environmental Engineering



A quality choice
NASA picks Rice's Daniel Cohan for Air Quality Applied Sciences Team

Rice News staff

Daniel Cohan, an assistant professor in civil and environmental engineering at Rice, has been appointed by NASA to a new Air Quality Applied Sciences Team (AQAST). The team will pursue innovative applications of satellite and other data to inform air-quality management.

Cohan, a Fulbright scholar and recipient of a prestigious National Science Foundation CAREER Award, is one of 19 American scientists to win five-year NASA grants. Their research and recommendations will help the agency best utilize the massive amount of data produced by instruments above Earth.

Team members are experts in remote sensing, modeling and air-quality management, according to the AQAST website, and "have the resources to carry out quick-turnaround research responding to urgent and evolving needs."

The group will meet for the first time in Boulder, Colo., in May.

Cohan said NASA has made great strides in recent years in its ability to see and analyze pollution from space. "NASA has spent hundreds of millions of dollars to launch satellites that measure air pollutants, and the purpose of the applied sciences team is to take that data and put it to better use, to inform science and air-quality management," he said.

"What's really exciting is that the generation of satellite devices deployed over the past decade has enormously expanded the opportunities for research. They have better sensors, and scientists at NASA and in Europe have developed new technology for taking the signals they receive from space and creatively using them to get increasingly accurate estimates of pollution.

"For example," he said, "10 years ago the best you could get to estimate levels of nitrogen dioxide was a resolution of about 100 kilometers. Now we're getting resolutions on the order of 10-20 kilometers."

That's important in Houston, he said, "where we're trying to resolve emissions from the Ship Channel and an urban area. At that resolution, you can start to make some headway in understanding what's happening on an urban-to-regional scale."

Cohan said that until recent years, satellites gave scientists readings of nitrogen dioxide for a particular area only once every six days. Now there's a pass once a day, and he looks forward to a time when geosynchronous satellites "can give around-the-clock measurements of pollutants of interest."

The new group will be led by Cohan's undergraduate adviser, Daniel Jacob, the Vasco McCoy Family Professor of Atmospheric Chemistry and Environmental Engineering at Harvard University, and will include his Ph.D. adviser, Armistead Russell, the Georgia Power Distinguished Professor of Environmental Engineering at Georgia Tech.

While the results of the group's efforts remain an open book, the approach follows a well-established NASA model, Cohan said. "In other areas, including space exploration, NASA has formed teams of scientists to advise its direction, but they've never attempted to do this for air quality," he said. "They decided this would be a great way to catalyze research."

Cohan's Rice research group develops photochemical models to apply to air quality management, uncertainty analysis, energy policy and health impact studies.

Data generated by NASA plays a key role in that process. "We are using NASA satellite measurements of nitrogen dioxide to infer the rates of emissions coming from cars and factories," he said. "It's interesting to look bottom-up at what you think is coming out of those sources, and top-down from space at how much of this pollution is actually out there, to see if they're consistent. If not, that points to gaps in our current understanding that might be interesting to explore."

Cohan said he would bring unique experience to the team. "Unlike most scientists, I actually worked for a state agency (as an air quality expert for the Georgia Environmental Protection Division) before coming to Rice, helping develop air pollution strategies for the state. I'm sure we'll be thinking about how to take satellite and modeling results and use them to improve the decision-making process."

He anticipates involving graduate and undergraduate students from his research group at Rice to take part in the work.