Infrared characterization of fine-scale variability in behavior of boreal forest fires

Abstract

Spatial and temporal variability in forest fire behavior, caused by differences in microsites, fuel types and condition, topography, and other factors across even relatively small areas, has been poorly characterized in most previous studies. Past characterization of forest fires has often been limited by monitoring techniques that relied on timing systems in coarse-resolution sampling grids. We report documentation and analysis of fire behavior for several experimental fires using a camcorder-sized infrared camera mounted in a helicopter hovering over the target fires. These fires were conducted as part of the Russian FIRE BEAR Project in boreal Pinus sylvestris L. forests of central Siberia. Final results provide quantitative information on fire front location, rates of spread, temperatures, and total radiation energy (kW/m²) observed during the fires at resolutions from 2.5 to 1.0 m across experimental burn plots ranging from 2.3 to 4.0 ha. Further postfire analysis using GIS produced a detailed spatial and temporal quantification of fireline intensity (kW/m) across the plot area. This type of infrared monitoring and analysis helps to support clearer assessment of relationships between fire behavior and ecological impacts. Such data permit accurate fire behavior estimates at various temporal and spatial scales rather than using an overall plot average. This method allows the sample size to be quite large, so that statistical analysis of the fire behavior data can provide an associated level of confidence.