Canadian Forest Service Publications

Direct estimation of Byram's fire intensity from infrared remote sensing imagery. 2017. Johnston, J.M.; Wooster, M.J.; Paugam, R.; Wang, X.; Lynham, T.J.; Johnston, L.M. International Journal of Wildland Fire 26(8): 668-684.

Year: 2017

Issued by: Great Lakes Forestry Centre

Catalog ID: 39019

Language: English

Availability: PDF (request by e-mail)

Available from the Journal's Web site.
DOI: 10.1071/WF16178

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Byram’s fire intensity is one the most important and widely accepted metrics for quantifying wildfire behaviour. Calculation of Byram's fire intensity requires measurement of fuel consumption, heat of combustion and rate of spread; existing methods for obtaining these measurements are either inexact or at times impossible to obtain in the field. This paper presents and evaluates a series of remote sensing methods for directly deriving radiative fire intensity using the Fire Radiative Power (FRP) approach applied to thermal infrared imagery of spreading vegetation fires. Comparisons between the remote sensing data and ground-sampled measurements were used to evaluate the various estimates of Byram's fire intensity, and to determine the radiative fraction (radF) of a fire’s emitted energy. Results indicate that the Byram's fire intensity along an advancing flame front can be reasonably estimated (and agrees with traditional methods of estimation (R² = 0.34–0.73)) from appropriately collected time-series of remote sensing imagery without the need for ground sampling or ancillary data. We further estimate that the radF of the fire’s emitted energy varies between 0.15 and 0.20 depending on the method of calculation, which is similar to previous estimates.

Plain Language Summary

This study examines methods of measuring fire behaviour. It proposes new ways of measuring fire intensity (FI) using infrared imaging, and tests them using experimental data. Three methods of doing this were tested, two of which are newly proposed, and one that was proposed before but never tested. In the end we found that the new methods performed very well, and that the previously existing method may/may not work. The impact of this study may be significant. Traditionally FI could only be calculated by conducting pre and post fire ground sampling – meaning that it could only be done on experimental burns and was very costly. With these methods FI can now be calculated on any fire where infrared imagery is available – with no ground sampling. This opens the door to much more precise FI calculation and may allow it to be measured on wildfires.