Simulating the Atmospheric Response to a Wildland Fire using a Cloud-Resolving Model

Wildland fire behavior can be very difficult to predict because of the inherent non-linearities and multi-scale processes associated with combustion. The circulation and complex flows in the vicinity of a fire are primarily driven by heat and moisture release from the fire. Extreme conditions in the fire environment make collecting meteorological observations difficult, so we employ a high-resolution model to simulate the atmospheric responses to a fire. For this project we have chosen Cloud Model 1 (CM1) because it is designed to simulate high-resolution, cloud scale processes. A surface sensible-heat flux was added to CM1 to approximate the heating fire at the surface. These surface sensible-heat fluxes are used to examine the resulting fire-induced circulations and complex flows.  Using CM1 allows simulations with fine spatial and temporal resolutions to provide a more detailed representation of the evolution of the fire-atmosphere system.  

For the purpose of this study, our focus is on the impact of the simulated fire on flows directly adjacent to and above the fire.  By focusing on these near-fire features, we address questions concerning the potential for fire-induced flows and the associated convective features to feed back on the fire.  In this presentation, we will show simulations that explore the sensitivities of fire-induced flows to variations in surface heat and moisture fluxes, stability profiles, and wind profiles. Variations in these characteristics change the complex flows, circulations and plume characteristics in the proximate to the fire. These simulations, when combined with the field studies and observations, will help diagnose and refine our understanding of fire-atmosphere interactions. The results from this study could potentially help fire managers with ground-based decision making when fighting fires.