Dylan Millet heads a team collecting air samples at a radio tower southeast of the Minneapolis-St. Paul metro area. The study aims to improve computer models used in climate research.
Above the snowy fields, a clear Teflon tube threads up a radio tower to capture a steady stream of cold air. Inside the little cement building below, a machine the size of a dishwasher measures the contents of the incoming air.
The landscape looks bucolic. But to Dylan Millet and his team studying atmospheric chemistry, it’s a frontier that is anything but calm.
“Minnesota stands right where the prairie, the eastern deciduous forest, and northern coniferous forests come together,” says Millet. “And we have this major urban area influencing things. There’s nothing like it.”
Millet combines three areas of expertise to improve predictions of how landscapes and atmosphere interact—pioneering field studies like this one, satellite observations, and three-dimensional computer modeling of atmosphere activity. Because of this unusual combination and the potential that his research holds for informing policy decisions and analyzing climate, Millet was named a McKnight Land-Grant Professor for 2010-12.
Research on climate depends on models, and Millet is improving them.
He brings a solid background in chemistry and interdisciplinary experience gained on the coasts—British Columbia as an undergraduate, California as a graduate student, and Boston as a postdoctoral researcher. He traveled a lot of miles using a mobile laboratory with a measurement tower to sample air quality on all kinds of landscapes. But standard measurement towers are only 10 meters high.
Millet was attracted to Minnesota not only because of its complex landscape but because of the 200-meter tower 30 miles southeast of St. Paul. Another University of Minnesota researcher in the Department of Soil, Water, and Climate had already negotiated an agreement with the station owner and run a sampling inlet part way up the tower for a separate study. Millet was able to use the same tower with a new inlet near the top.
“Samples from 200 meters up give a regional footprint,” Millet explains. “That size of footprint is the first of its kind for the type of chemical measurements we’re doing.”
On a sunny morning in November, Millet is visiting the station with two members of his team, Lu Hu and Mike Mohr. They’re all curious to see whether the equipment made it through a weekend snowstorm.
They connect a laptop computer to the mass spectrometer analyzing the air stream.
“We see a lot of the Twin Cities here,” says Millet, scanning the computer screen at the base of the tower. By “see,” he means in the data showing up on the computer screen. The post-storm data look good.
Outside, they peer up the tower to the inlet 200 meters up. They examine a photo shot with a zoom lens.
“It made it!” Mohr announces and grins.
Millet will be the first to emphasize that his team’s research is not about weather, but about climate and long-term chemical interactions between landscapes and the atmosphere. They are working to identify relationships between atmospheric quality and factors that humans can and can’t control.
“The tower’s unique position gives us an unprecedented dataset for untangling the importance of natural versus human effects on the atmosphere,” says Millet.
Storms have caused some of the biggest challenges over the first two years of the study. Almost every thunderstorm means a lightning strike, and almost every strike means an interruption in power. Turbulent weather in any season can knock out the sampling inlet, and hiring tower climbers to reposition the inlet or tubing costs thousands of dollars. High dew points and temperature fluctuations due to air conditioning in the station during the summer created problems that had to be identified, analyzed, and solved.
There’s always something different in the real world than in the lab, which is exactly why field research like this is so important for continually improving computer models.
In the beginning, the station didn’t have an internet connection, either, so nothing could be checked remotely. One of the goals is to develop automation as much as possible, calibrating sequences and applying technology for the greatest efficiencies.
Millet has assembled a team that is clearly excited about the research and loves solving problems. Mohr, who grew up on a farm near New Ulm, Minnesota, asked how he could get involved after taking a class shortly after Millet arrived. Lu, a graduate student from China, is interested in gaining experience with tools that can accurately assess air quality and predict impacts on climate.
So far, Millet’s research has supported a total of six members including two undergraduates, two graduate students, and two postdoctoral researchers. The McKnight Land-Grant Professorship has only increased the potential.
“The chemical composition of Earth’s atmosphere is changing rapidly as a result of human activity,” according to Millet. “A main theme in my research is the interplay between human activity and natural processes in determining the overall chemical impacts of atmospheric gases.”
Millet began down his career path as a college freshman because of an outstanding chemistry professor. As a graduate student, he began to see the potential for applications to environmental research. Today, he is motivated not only by the intellectual challenge and opportunity to apply research but interaction with students.
“I’m here to do research and teach,” he says. “I get to do that. I love what I do.”
Dylan Millet, soil, water, and climate: Atmospheric chemistry—linking land-atmosphere exchange to air quality and climate.