The Role of Fire-induced Turbulence on Ember Transport

The severity and frequency of wildfires have risen dramatically in recent years, drawing attention to the term "wildland-urban interface" (WUI): the region where man-made structures meet wildland vegetation. The dominant mode of fire-induced damage in the WUI is from firebrands, which can travel large distances away from the fire-front and cause spotting ignitions. Moreover, the wind gustiness and turbulence induced by wildland fires play a vital role in their transport. However, such fire behavior is not well understood. We use WRF-Fire, a coupled fire-atmosphere numerical model, to investigate the role of fire-induced turbulence on ember transport over complex terrain as a major driver of wildfires in the WUI. We show that a majority of embers travel a short distance from the fire ignition point during a grassland fire when the feedback from the fire is taken into consideration. However, when fire is not ignited, the resultant turbulence is lower, and embers travel a shorter distance. Results from this study would help us understand the fire behavior at the fire-atmosphere interface, resolving the role of turbulence in ember transport during a strong wind-driven fire. It is hoped that this research would be beneficial to foresters, land managers, and several communities residing in the WUI; in that vein, it has the potential to make a major contribution to the scientific community and society at large.