Wildland fire acoustics: Measuring the inherent variability of a complex system

Wildland fires pose a unique challenge for the scientific community due to the complex processes and conditions shaping the fire environment. Not only are fire dynamics highly sensitive to perturbations, but fires are also inhospitable, destructive events that require customized equipment for scientific evaluation. It is within these constraints of monitoring unsteady hydrodynamic events with highly variable energy emissions that the idea of leveraging acoustic emissions to advance understanding of wildland fires was born. Wildland fire acoustic emissions extend through and beyond the range of human hearing. In recent years, studies found that sonic to ultrasonic popping events from rupturing vegetation reveal details about the vegetation and the fire-vegetation relationship. Likewise, the production of infrasound has potential ties to fire geometry and combustion dynamics. The roaring sounds that warn us of dangerous fire behavior occupy a portion of the human range of hearing and yield untapped knowledge about fire-atmosphere interactions. These measurements move beyond observing acoustic emissions to directly aid the previously under-studied nature of inherent variability found in wildland fires. This talk will explore the state of the science with a focus on capturing fire variability and explore next steps in acoustic remote sensing of wildland fires.