Characterizing wildfire dynamics in steep terrain: a canyon fire field experiment

Wildfire dynamics are a highly coupled system depending on not only wildland fuel characteristics but also on topography and weather. Steep terrain features like canyons have been widely reported to produce significant effects on wildfire dynamics, such as sudden fire accelerations. However, these effects are poorly studied and not correctly captured in current models. Furthermore, observational data of wildfire dynamics in steep terrain is extremely scarce. In this work, we will present the study design and preliminary results from a canyon fire field experiment conducted in California (USA) in October 2022. The experiment was set up so that a high-intensity head fire was started and allowed to spread freely up a canyon of approximately 1 km in length and 300 m in elevation difference. The vegetation primarily consisted of chaparral shrubs. Fire dynamics were monitored using airborne multispectral infrared sensors. Vegetation was characterized before and after the burn through airborne lidar scans. Additionally, fire-weather interactions were investigated leveraging Doppler lidar and radar sensors as well as in-situ micrometeorological towers. A fire eruption was observed when the fire entered the canyon, providing evidence of terrain-induced modifications to fire behavior. Datasets like this one are key to study the complex interactions between fire dynamics, vegetation properties, terrain characteristics, and weather dynamics, and constitute an important resource for model development and validation.

Acknowledgements: This work was supported by the U.S. National Science Foundation (NSF) under award number 2053619, the NSF-IUCRC Wildfire Interdisciplinary Research Center, and the EU COST Action NERO (CA22164). The authors also thank the California Department of Forestry and Fire Protection (CAL FIRE) for coordinating the field experiment.