Scientists watching a Midwestern thunderstorm discovered it sucking a river of ozone from high in the sky and dumping it in the lower atmosphere, a find that may require them to tweak some computer models that simulate the impacts of climate change.
While ozone acts as a shield against ultraviolet radiation when it's in the upper reaches of the atmosphere, it's a source of pollution and a heat-trapping greenhouse gas when it's near the Earth's surface.
Instruments aboard a NASA jet picked up what researchers called a "ram's horn" of ozone, a pathway swirling downward around the edge of a May 2012 storm over Kansas.
Thunderstorms were already known to produce ozone through lightning, which releases a burst of nitrogen oxides that then react with other trace gases. University of Oklahoma meteorologist Cameron Homeyer told VICE News the "ram's horn" drew ozone from the stratosphere down to the troposphere, the closest level of the atmosphere to Earth's surface, at higher levels than normally produced by lightning.
"The climate is especially sensitive to changes in ozone there, in the upper troposphere and lower stratosphere," said Homeyer, the co-author of a new paper on the find. "In this case, what you're doing is enhancing the effective concentration of ozone in the upper troposphere by encouraging more rapid transport from the stratosphere downwards."
The findings have been published in the peer-reviewed journal Geophysical Research Letters. Previous studies had suggested that storms were drawing ozone out of the stratosphere and into the troposphere, the layer of air closest to the Earth, but this is "the first unambiguous observation" of the process, the paper states. Scientists also reproduced the effect in a computer simulation on the ground, Homeyer said.
Computer models used to predict climate change may need to be adjusted for a new source of ozone.
The findings suggest computer models used to predict climate change may need to be adjusted for a new source of ozone, the authors wrote.
"This may be a significant pathway because hundreds of these deep convective storms occur over the continental U.S. during summer," they wrote.
Homeyer cautioned that the effect has been documented in only one storm, and further study is going to be needed.
"We don't have very many additional measurements like this — direct measurements at the edge of a storm — to be able to say how often this is happening," he said. "Is it happening around every storm? Is it only a particular type of storm? Those are some of the questions that still remain."
Research meteorologist Lesley Ott, who has studied atmospheric ozone for NASA, called it "a really important topic."
"All of the things that control ozone have a really strong impact on tropospheric chemistry," Ott told VICE News. "And that affects things where we live, eventually, down near the surface."
But she said thunderstorms "can be very individual kinds of beasts."
"We need more research to understand how representative this is, how common this is," she said. "When we have a better sense of how it fits into the big picture, then we can start to think about how important this is to include in climate models and trying to find better ways to do that."
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