Fire/atmosphere Feedbacks that Control Wildland Fire

Wildfires pose a threat to life, property and critical infrastructure, but wildland fire is an unavoidable part of the nature. In order to improve our ability to cope with wildfires and anticipate their evolving roles on the earth system we need to better understand how they interact with their environment. Recent fire behavior research illustrates the importance of the two-way feedbacks between fires and the surrounding atmosphere, which is influenced by the vegetation structure and topography as well as ambient winds. The effectiveness and consequences of fuels management activities are tied not only on the removal of combustible fuel, but also on the changes in the ventilation induced by decreased vegetation drag, which can potentially increase fire spread. Safe use of prescribed fires to reduce fire risk while accomplishing ecologic objectives typically depends on fire practitioner’s ability to anticipate the interaction of multiple fires. This interaction is controlled by the competition between their fire-induced indrafts. Topographic influences on fire behavior are dominated by terrain-induced changes in entrainment patterns that control the patterns of heat transfer to unburned fuel. Multi-scale two-way fire/atmosphere feedbacks determine heterogeneous fire line dynamics and thus fire spread, the effects of fires on ecology and the near-field lofting and transport of the smoke. Unfortunately, deciphering the complex interaction between fires and surrounding atmosphere through field and laboratory experiments alone has been challenging, but recent advancements in computing power have created new opportunity for the complimentary use of numerical models to provide additional perspectives concerning fire/atmosphere feedbacks that have previously been challenging to explore. Examples of ways that the interactions between fire and surrounding atmosphere dictate fire behavior and the use of numerical models to investigate this coupling will be discussed.