Trinity researchers take to the skies to mesaure San Antonio ozone levels
by Nicolette Good ’07
Five students were spotted on campus launching large, high-altitude balloons into the air last year. Standing six and a half feet tall, the white balloons were equipped with instruments meant to answer one question: How much ozone is in Texas’ atmosphere on any given day?
The Trinity Ballooning Project began when St. Edward’s University subcontracted Trinity to collect valuable ozone data from the skies over San Antonio’s large metropolis. The project was co-sponsored by Leslie Bleamaster ’98, geosciences adjunct professor, and Marilyn Wooten, chemistry lecturer, and involved Trinity students Malcolm Conner ’18, Enrique Garcia ’19, Gabriel Levine ’18, Mariel Santos ’18, and Huda Syed ’18, as well as a student from the University of Texas.
From August to October 2017, the team launched 24 balloons equipped with ozone sondes—probes that capture information about the gases around it and automatically relay their findings to the Trinity team on the ground. Each launch required roughly eight hours of work, from preparing the sondes to field launch. Sometimes the group would know a launch date weeks in advance. Other times, they’d be instructed to launch that very day, which meant the students had to act fast.
“We had to call three air authorities to get the OK before we could launch,” Garcia says. “They might tell us we have to launch in the next two minutes because another aircraft is coming on. When they say two minutes, they literally mean two minutes. We had to hurry up and secure everything and launch.”
During flight, the sonde detected how much ozone was in its path. Ozone is a gas composed of three atoms of oxygen (O3). Naturally occurring ozone high in the stratosphere shields us from the sun’s harmful ultraviolet rays. But, ozone can be created at ground level when sunlight reacts with pollutants. Breathing ozone can trigger or worsen health problems including chest pains, coughing, throat irritation, and airway inflammation.
Once the Trinity team collected the data, it was sent to St. Edward’s professor Gary Morris, principal investigator on the initiative, where it was then interpreted and modeled. Morris, who worked in conjunction with the Texas Commission on Environmental Quality (TCEQ), shared the data among local and state officials who provide guidance for managing days with elevated levels of ozone.
“This kind of data can help a city anticipate environmental changes triggered by population changes,” Wooten explains.
The TCEQ monitors air and ground ozone levels using spectroscopy—a technology that gathers information based on how light interacts with matter in its path. Ozone has a specific light signature, which tells a spectroscopic instrument whether the gas is present. But spectroscopy only indicates ozone is present, while ozone sondes reveal a much more detailed picture of how much ozone is at each height, from the ground up.
“We are getting a profile from the surface all the way up, and looking at the changes,” Bleamaster says.
As the balloons floated up to nearly 18 miles (30 km) above Earth’s surface, the students watched their computer screens, the results flowing in. Once risen, the balloons are meant to pop from lack of atmospheric pressure at a certain elevation, then parachute back to the ground.
“One of the things I learned from this experience is that San Antonio’s air is pretty good and clean,” Bleamaster says. “Even though we’re a potential ozone accumulator or generator, our levels are pretty low, comparatively speaking.”
“This experience helped me to understand more about the sky,” Wooten adds. “We think of air as nothing, but we are really in a soup of air. There’s a whole world in the sky. ”