The Boulder area features no shortage of men and women who bike to work. Not as many of them are working while on two wheels.

Those who regularly cycle or run across Boulder County's highly variable topography have likely noticed, at certain times of day, the sensation of hitting warmer or cooler air pockets as they go.

John Cassano, on his regular bike commute from Louisville to the University of Colorado, has experienced them as well. But, as an associate professor in the University of Colorado's atmospheric and oceanic sciences department, feeling the changes was just a starting point for Cassano.

More than a year ago, he said, "I was having a conversation with a former student of mine, and he said he had this hand-held instrument that was able to log data at a high time rate. It could log data every couple of seconds."

As soon as he got off the phone with the former graduate student, Mark Seefeldt, he ordered a Kestrel 4000 weather and wind tracker and put it on his bike.

"The changes I was seeing occurred over such small distances when I was biking, I needed something that had a fast response time," said Cassano, who came to Colorado in 2001.

Mounting the Kestrel 4000 on his handlebars, along with an Edge 800 GPS, and studying the data resulted in his publishing in the Bulletin of the American Meteorological Society a paper he said has won him a surprising level of positive response from his peers.


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Cassano's paper documented temperature variations of more than 10 degrees Celsius — 18 degrees Fahrenheit — over distances as short as 1 kilometer. As an expert in atmospheric sciences, Cassano has long understood that significant pooling of cooler temperatures can occur in topographic depressions before sunrise and after sunset, most markedly when it is clear, with little or no wind.

Still, he said, "I was just shocked that it was so abrupt and pronounced. I understood the processes, but I was surprised at how abrupt some of the changes I saw actually were."

'Everyone notices it'

What started out as a matter of curiosity for Cassano quickly evolved into what he saw as a potential learning tool in the classroom.

"I'm sure students in my classes have seen this, as they have walked from campus down to Boulder Creek and have noticed the big changes in temperature," Cassano said.

"Everyone notices it, everyone experiences it, and I thought this is a way I could tie into the experiences that the students have, and put some numbers to it and talk about the processes. That's what motivated me to write the article."

Mobile weather data collection is not new. The American Meteorological Society in 2009 formed a committee to focus on mobile observations and their potential use in the forecasting and transportation sectors.

Bikes have been used previously, too, Cassano noted, although previous studies he has seen focused primarily on climatological differences between urban and rural areas, and not the variations in topographical effects as he has done.

"It's a pretty small set of people that have done this before," said Cassano, who is also a fellow at CU's Cooperative Institute for Research in Environmental Sciences.

Sheldon Drobot, who knew Cassano while he was also at CU, is now deputy director for the Weather Systems and Assessment Program at the National Center for Atmospheric Research. Much of his work focuses on the impacts of weather and climate on surface transportation. Up to now, Drobot said, most of the attention on mobile weather platforms has been on "things with engines."

"Bikes are a great addition to that on the road," Drobot said.

Seeking more applications for the research

Cassano is commuting at this time of year after sunrise, when the temperature variations are not so pronounced, so he is not now collecting data with the "weather bike." But he is often thinking about broader applications for his research.

"I guess the big place I want to go next with this is finding a good way to integrate it into my classes," he said. "I think there is a real potential for students to go out and collect data — a powerful way to link to the concepts they're learning in their lectures, and say, 'Wow, this is exactly what John was talking about in class.'"

Cassano said he recently was reading about a summer class being taught at the University of Arizona for which students embark on a two-week "bike-packing" excursion into the Colorado Plateau in the Four Corners area to examine the area's geology.

"I've thought it would be interesting to link up with them and put the Kestrels on their bikes as well, doing weather along with the geology," he said.

"I'm thinking about creative ways to get this into the hands of students."

Contact Camera Staff Writer Charlie Brennan at 303-473-1327 or brennanc@dailycamera.com.