Researchers at the University of California, Irvine have conducted groundbreaking field experiments in the Sierra Nevada mountains to better understand how embers from wildfires cause spot fires. These experiments aim to help authorities improve disaster modeling as climate change increases the frequency of such events.
The team set up their study at UC Berkeley’s Blodgett Forest Research Station, using wood from ponderosa pine and Douglas fir trees, which are common fuels in Sierra wildfires. During nighttime trials, high-speed imaging was employed to observe flame dynamics over 20 minutes. A particle tracking velocimetry technique provided insights into flow dynamics and turbulence by following ember trajectories.
Sheet pans filled with water were used around the fire to collect firebrands for laboratory analysis of their size, shape, and density. “Climate change is making wildfires larger and more complex,” said Tirtha Banerjee, a UC Irvine associate professor involved in the study. “Our team has made a major contribution by drilling down into the physics and kinematics of firebrand propagation using advanced instruments and techniques.”
The research also focused on how frequently embers are produced in high-temperature plumes. Current computer models assume that ember propagation correlates with fire intensity. However, Banerjee’s group discovered that ember creation occurs intermittently in large bursts, making it challenging to predict their spread.
“Present models can underestimate the potential for large firebrands to be lofted and transported greater distances,” noted Alec Petersen, lead author of the study and a postdoctoral scholar at UC Irvine. He emphasized that rare events involving large embers ejected simultaneously with strong updrafts could be responsible for starting spot fires farther away than expected.
Rob York from UC Berkeley assisted with these field experiments funded by organizations including the National Science Foundation, NASA, and the U.S. Department of Agriculture.
UC Irvine continues its efforts under its Brilliant Future campaign launched on October 4, 2019. The campaign seeks $2 billion in philanthropic investment to enhance student success, health wellness, research initiatives among others.
Founded in 1965, UC Irvine is recognized as one of America’s top public universities with notable achievements across various fields including producing five Nobel laureates.
