Shining a light on the ‘big monster’

Shining a light on the ‘big monster’

SAN JOSE — Craig Clements is shining a light on a monster.

The monster, in this case, is no ordinary bogeyman, but the towering smoke plume produced by a wildfire.

Clements, who oversees the Fire Weather Research Laboratory at San Jose State University, is using Doppler LiDAR, or light detection and ranging, to peer into the inky darkness. It’s a new application for a decades-old technology. But with it, Clements, Department of Meteorology and Climate Science assistant professor Neil Lareau, and a small cadre of graduate students have discovered that wildfires create their own weather systems. And those weather systems, in turn, fuel extreme fire behavior.

The team’s cutting-edge research could lead to models that better predict the spread of fires and potentially save lives.

“Craig is doing something that’s a little different,” said Chris Waters, a battalion chief with the California Department of Forestry and Fire Protection, or Cal Fire. “He’s not looking at the ground or the fire itself. He’s looking at that big monster that’s perched up over the top of it.”

Wind speeds and directions within a plume can be detected every minute with Doppler LiDAR, a remote-sensing method that uses light in the form of a pulsed laser to measure distances.

“There is no capability to do that on a wildfire incident except with this tool,” Clements said.

Mounted to the bed of a four-wheel-drive pickup truck, the rectangular instrument has been pointed at the plumes of 23 different conflagrations over the past couple of years, including the El Portal Fire that scorched 4,700 acres in Yosemite National Park in 2014.

The team documented its observations from the El Portal Fire in a paper recently published in the Journal of Applied Meteorology and Climatology. For instance, fire-generated updrafts and strongly turbulent eddies formed along the edges of the plume.

“The stronger the updraft, the farther (away) a spot fire can occur,” said Clements, using the term for a secondary blaze that is sparked by a drifting ember.

Spot fires made the recent Detwiler Fire in Mariposa County particularly challenging to fight, said Cal Fire Battalion Chief Tim Chavez. As of Wednesday, crews were still working to achieve full containment of the blaze that has charred nearly 82,000 acres since July 16.

“We’d be turning a corner and thinking we had the fire picked up and it would show up a long way away spreading freely and we didn’t even know it was there,” said Chavez, whose duties include assessing the character of a wildfire and determining what tactics to use.

The findings by Clements and his team confirm long-standing, but previously unvalidated predictions, for how smoke plumes rise from fires and provide new insights into the processes that control how high and how far wildfire smoke will spread.

Nick Anderson, program director of the National Science Foundation’s Division of Atmospheric and Geospace Sciences, said the research offers “rare observations of the behavior of wildfire smoke plumes.” The foundation funded the team’s research with a $900,000 grant.

“Improved understanding of wildfire plumes is important for determining whether smoke will stay near the ground and affect air quality and visibility, or whether it will rise into the atmosphere and potentially affect clouds and the amount of sunlight reaching the ground,” Anderson said.

The research also could save lives. Wildfires killed 168 firefighters nationwide between 2006 and 2015, according to the most recent fatality report from the U.S. Fire Administration.

“Whether it’s Cal Fire, the Forest Service or local government, fire agencies are still suffering an unacceptable level of fatalities because of wildland fire and extreme fire behavior,” Waters said. “These guys are doing this research to try and help us answer questions and make us safe.”

Clements is in the process of applying for another grant that would employ an aircraft to study plumes.

“We’re trying to develop new tools to better predict fire spread,” he said. “Our contribution to that goal is to collect the best state of the science observations around active wildfires.”

Brenda Belongie, a meteorologist with the U.S. Forest Service, said she wants to partner with Clements and his team to study other wildfire-related phenomena, including the strong down-slope winds that develop in the Mendocino National Forest’s Grindstone Canyon, where 15 people were killed in the Rattlesnake Fire of 1953.

“We’re really looking forward to a partnership with him,” she said. “Anytime you can put the eggheads with the application geeks, you get a better product. We have questions and they can find answers.”