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areas of a fire. This relationship is a useful way of quantifying one fire’s 
burning characteristics relative to another fire. Fire intensity is usually 
expressed as an energy release rate which requires knowledge of rate of spread 
and fuel quantity consumed. The fuel quantity parameter can be obtained from 
measurements on the ground, but if these are impossible to obtain, fires can 
still be usefully characterized in terms of spread rate and duration of burning, 
both of which can be measured on the IR imagery alone. 
Apparent temperature range of each color isothermal zone on a given 
IR image can be assigned from calibration curves supplied by the equipment 
manufacturer. A discrete non-linear temperature curve is provided for each 
of the seven IR camera apertures and scale factors are applied to take into 
account the sensitivity setting used on any given image. For instance, aperture 
f/14 is suited to many fire situations as in full scale this aperture covers 
temperatures from 220 to 850 C, which approximates the range from woody fuel 
ignition temperatures to the temperatures measured in concentrated beds of 
rapidly burning forest fuels. The ten colors displayed on the monitor allow 
easy differentiation of intensely burning areas from areas of smoldering com 
bustion. While absolute temperatures cannot be calculated because of un- 
quantifiable variables affecting IR radiation emissivity and atmospheric 
absorption, relative energy regime comparisons between fires can be made 
satisfactorily. 
IMAGERY FROM FIRE BEHAVIOR RESEARCH APPLICATIONS 
Examples of imagery obtained from the three kinds of forest fire 
data sources being utilized in the research project are included here. 
First is an example of a prescribed bum in British Columbia coastal 
logging residue in which large quantities of woody waste remaining after 
harvesting the standing crop are deliberately burned during favorable weather 
regimes in order to reduce fuel volumes to reduce hazard of wildfires. Fire 
behavior in such fuels is of particular concern because spread rate can be 
rapid when fine fuels are dry and controlling fires in such heavy fuels is 
difficult. Infrared mapping of such fires provides data on spread rate and 
duration of burning or rate of energy release which is difficult to obtain 
by other means, since heavy smoke obscures conventional photography, leaving 
time-consuming ground instrumentation as the only other means of collecting 
this information. 
Figures 4 and 5 are conventional photographic and IR imagery 
respectively of such a prescribed fire which is still being ignited along 
fire guards protecting adjacent standing timber. Figure 6 shows the same 
fire 15 minutes later from the same height of 854 m above ground. Convective 
forces have spread the fire across the 120 m wide previously unburned opening 
from both directions. Spread rates of 6.3 m/min. were measured from the upper 
fire front shown in Fig. 5 and 2.9 m/min. from the lower front to the point 
of convergence seen as the light-toned irregular strip in Fig. 6 . 
Fig 
Fig