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Why do volcanic ash plumes wreak havoc in the jet stream? Researchers have found that “the jet stream essentially stops the plume from rising higher into the atmosphere,” says volcanologist Marcus Bursik. “Because the jet stream causes the density of the plume to drop so fast, the plume’s ability to rise above the jet stream is halted: the jet stream caps the plume at a certain atmospheric level.” (Credit: Jet Stream/Flickr)

BUFFALO (US)—The jet stream, an area in the atmosphere favored by airline pilots, also seems to be the area most likely to be affected by plumes from volcanic ash.

“That’s a problem,” says Marcus Bursik, a volcanologist at the University at Buffalo and one of the foremost experts on volcanic plumes and their effect on aviation safety, “because modern transcontinental and transoceanic air routes are configured to take advantage of the jet stream’s power, saving both time and fuel.

“The interaction of the jet stream and the plume is likely a factor here,” says Bursik, professor of geology. “Basically, planes have to fly around the plume or just stop flying, as they have, as the result of this eruption in Iceland.”

In some cases, if the plume can be tracked well enough with satellites, pilots can steer around the plume, he notes, but that didn’t work in the recent Eyjafjallajokull Volcano eruption in Iceland because the ash drifted right over Britain.

Bursik participated in the first meetings in the early 1990s between volcanologists and the aviation industry to develop methods to ensure safe air travel in the event of volcanic eruptions. He and colleagues authored a 2009 paper on the topic, published in the Journal of Volcanology and Geothermal Research.

“In the research we did, we found that the jet stream essentially stops the plume from rising higher into the atmosphere,” he says. “Because the jet stream causes the density of the plume to drop so fast, the plume’s ability to rise above the jet stream is halted: the jet stream caps the plume at a certain atmospheric level.”

Bursik says that new techniques now in development will be capable of producing better estimates of where and when ash clouds from volcanoes will travel.

He and his colleagues have proposed a project with researchers at the University of Alaska that would improve tracking estimates to find out where volcanic ash clouds are going.

“What we get now is a mean estimate of where ash should be in atmosphere,” says Bursik, “but our proposal is designed to develop both the mean estimate and estimates of error that would be more accurate and useful. It could help develop scenarios that would provide a quantitative probability as to how likely a plane is to fly through the plume, depending on the route.”

Coauthors on the jet stream paper include researchers from the Russian Academy of Sciences, University of Maine, Orono, and the Jet Propulsion Laboratory at California Institute of Technology.

The research was funded by NSF, the National Aeronautics and Space Administration, and California Institute of Technology and Science Applications International Corp.

University at Buffalo news: www.buffalo.edu/news/