BOULDER, Colo., July 8 (UPI) -- New research suggests it's not just the hot Santa Ana winds that propel California's wildfires. They sometimes arrive alongside an atmospheric phenomenon known as stratospheric intrusions.
In a recent study, researchers at NOAA determined that the winds occasionally pull extremely dry air from the upper atmosphere down to Earth's surface, exacerbating already fire-friendly conditions.
To better understand the affects of intrusions, researchers looked at data collected during California's May 2013 "Springs Fire," a blaze that burned 25,000 acres roughly 50 miles northwest of Los Angeles.
Ozone, wind data and other atmospheric markers revealed the arrival of a stratospheric intrusion on the initial day of the fire, bringing with it an uptick in ozone (O3) and a precipitous drop in humidity. The hot and dry conditions fueled a fast-burning fire until rain arrived a few days later.
The same intrusion triggered pollution warnings at ozone monitoring sites across Southern California. Exposure to ozone pollution can cause lung damage.
"Stratospheric intrusions are double trouble for Southern California," Andrew Langford, a research chemist at NOAA's Earth System Research Laboratory in Boulder, Colorado, explained in a press release. "We knew that the intrusions can add to surface ozone pollution."
"Now we know that they also can contribute to the fire danger, particularly during La Niña years when deep intrusions are more frequent, as recently shown by our NOAA colleagues at the Geophysical Fluid Dynamics Laboratory," he said.
The upside of the new findings -- detailed in the journal Geophysical Research Letters -- is that atmospheric models can predict these intrusions.
"The atmosphere could give us an early warning for some wildfires," Langford added, giving officials extra time to intelligently deploy firefighting resources.