New radar helps scientists see inside wildfires and fits on the back of a truck

Scientists studying California’s devastating wildfires are using a powerful new radar system that could help them better understand how they spread and how firefighters should fight them.

The mobile Ka-band Doppler radar rig is similar to what meteorologists use to monitor the weather, but it is finely tuned to detect ash particles in a fire plume, said Craig Clements, the director of San Jose State University’s Fire Weather Research Laboratory.

It works by emitting bursts of millimeter wave energy that bounce off particles and can be detected by the radar.

The system got its first real world tests last month with the Briceburg Fire near Yosemite National Park and the Kincade Fire, which has burned more than 77,000 acres and destroyed 374 structures in Northern California. The Kincade Fire has been burning since October 23 and is about 80% contained, according to Cal Fire.

“We really want to understand the wind flow around fires. We don’t understand how fires create their own weather. We don’t know what impact that has on fire spread.”

He said they’ve been able to detect and monitor embers as they are pulled up through the fire’s column of smoke and then dropped downwind of the fire, which can start new fires.

The radar can also see through the smoke to see structures such as fire whirls, which he compared to mini fire tornadoes that are erratic and dangerous and often hard to see.

“Right now, we’re doing research because we want to understand the physics of wildfire spread and how fires create their own weather and all that fire atmosphere interaction that we do, so it’s scientifically very valid, but there’s an operational need too.”

He said firefighters could use the information to help them decide to deploy their crews.

Clements and his students have studied about 30 fires over the years using a Doppler LiDAR system that is similar to radar, but it uses a pulsed laser to measure ranges and other information.

The new radar can detect structures inside the fire and is much faster, Clement said. It takes about 45 seconds to scan a fire’s plume with LiDAR, but the new radar can do it in five or 10 seconds.

“We’re getting to see a lot of different structures faster, which means we can describe the flow easier because if we have one snapshot that’s great, but if we have multiple snapshots we can almost see the structures moving,” Clements said.

The system weighs about 600 pounds and is mounted to the back of a specially-equipped Ford F-250, so Clements and his students can quickly move it into place and take readings. Once they find a good spot, it can be up and running in less than three minutes.

“With that capability, we can position ourselves in any location,” Clements said.

Clements paid for the $650,000 system with a grant from the National Science Foundation.

“It’s pretty cost-effective,” he said — especially when compared to expensive firefighting equipment and the devastating economic impact of fires.

He said that he hopes that states will one day develop networks of radar systems to help firefighters predict how wildfires could spread.