USDA Forest Service

Fire and Environmental Research Applications Team


Fire and Environmental Research Applications Team
Pacific Wildland Fire Sciences Laboratory

400 N 34th Street, Suite 201
Seattle, WA 98103

(206) 732-7800

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United States Department of Agriculture Forest Service.

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Predicting Regional Haze from Wildland Fire

Fire Scenario Builder

Significant changes in fire severity and fire size are predicted for many ecosystems as a result of land-use change, climatic change, and fire exclusion. Warmer temperatures and associated drought significantly increase the area burned by fire (Littell et al. 2009).  Although large-scale vegetation change is constrained primarily by climate, change in fire regimes in response to climatic change could significantly alter vegetation patterns, because fire often provides critical constraints on vegetation.  Changes in dominant vegetation in turn affect the abundance and distribution of fuels, providing a feedback to fire-climate interactions.  We need to understand climate, vegetation, and fire as parts of a dynamic system in order to predict the responses of ecosystems to climatic change.

The Fire Scenario Builder (FSB) is a collaborative effort of the FERA and AirFire teams at the Pacific Wildland Fire Sciences Laboratory.  It simulates current and future fire starts and fire extent, using fire-regime statistics (fire frequency and fire-size distributions), mesoscale meteorology, and land-use and management scenarios. FSB uses a composite metric of fire weather, the FWI (Fire Weather Index) from the Canadian Forest Fire Danger Rating System (CFFDRS) as a control on simulated fire sizes.    We place realistic future fire scenarios on the landscape stochastically such that they can be used in the integrated modeling of regional haze (McKenzie et al. 2006).  We are currently working with the University of Washington, Washington State University, University of North Carolina, and the EPA, Atmospheric Modeling Division, on regional- and continental-scale implementation of the Fire Scenario Builder.


Figure 1: Components of the Fire Scenario Builder (FSB).  Flammability is a function of fuel moisture, which is predicted from meteorology, vegetation, and the Canadian Forest Fire Danger Rating System (CFFDRS). Ignition availability can be either from lightning or human causes. Fire starts depend on ignitions, and fire sizes on flammability. Output from the FSB comprises daily locations and sizes of fires, which are passed to BlueSky or other modeling frameworks to calculate consumption, emissions, and dispersion.


Figure 2: Predicted fire sizes (circles) from the FSB overlain on levels of FWI (colors) for (a) one “current” year (1996) and (b) one future year (2048), based on 36-km regional climate simulations. Figures courtesy of Serena Chung, Washington State University.


Littell, J.S.; McKenzie, D.; Peterson, D.L.; Westerling, A.L. 2009. Climate and wildfire area burned in western U.S. ecoprovinces, 1916-2003. Ecological Applications. 19(4): 1003-1021.

McKenzie, D., S.M. O’Neill, N. Larkin, and R.A. Norheim. 2006. Integrating models to predict regional haze from wildland fire. Ecological Modelling. 199:278-288.

Project Lead: Don McKenzie

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