Abstract

Visibility impairment from regional haze is a significant problem throughout the continental United States. A substantial portion of regional haze is produced by smoke from prescribed and wildland fires. An integrated system was developed for estimating regional haze from fire emissions, using new and existing computer models and continental-scale geographic databases. This integrated system not only estimates regional haze under current conditions, but also will allow us to extrapolate to future climate and land use.

There are three modules to the integrated system. A climate-fire-vegetation module estimates the effects of climate on wildland fire regimes and vegetation succession, combining a stochastic fire-scenario builder with either historical vegetation and fire regimes (current fire) or a dynamic vegetation and disturbance model (future fire). The fire-scenario builder uses real-time mesoscale meteorology to project wildfire events. A consumption and emissions module calculates particulate and aerosol emissions from biomass consumed in the fires. A smoke dispersion module then simulates the smoke plume and atmospheric dispersion of emissions from each fire.

To date, we have results from a 12-km domain in the Pacific Northwest, USA. Both the total amount and the spatial and temporal patterns of haze-producing emissions are sensitive to climatic variability, particularly synoptic weather patterns, and the stochastic nature of fire occurrence across the region. Integrated models such as ours are necessary to answer multi-disciplinary scientific questions and respond to broad-scale policy directives.