We have measured the surface temperature and emissivity of the forest floor as a function of time after the passage of the flaming fire front. This information is essential for remote sensing of wildland fires from airborne and satellite platforms. The goal of this project is to determine, for different forest ecosystem types, the length of time the burn scar will remain visible to mid and long-wave infrared sensors.

To perform these measurements we have developed lightweight, portable data recorders(1) that can simultaneously measure both the kinetic temperature (using thermocouples) and the radiant temperature of the forest floor. To measure the radiant temperature we use infrared thermopiles with 1.5 - 10 micrometer bandwidth. From the radiant and kinetic temperature we can obtain the emissivity as a function of time, which then gives us the obseravability of the burn scar. We sample up to 16 separate points during a fire passage which allows some amount of spatial averaging to compensate for variability of the forest floor cover.

We will present results from several types of northern Rocky Mountain forest types, pine barrens (pitch pine-scrub oak) and coastal grasslands. The results of these studies will be incorporated into estimates of burn-scar obseravbilty time for these different ecosystems.

This work was supported by the National Aeronautics and Space Administration under Grant NAG5-10051 and by the USDA Forest Service under a Joint Venture Agreement with the Rocky Mountain Research Station . This financial support has been greatly appreciated.

(1)Automanous field deployable wildland fire sensors, R. Kremens et al, Intl. J. of Wildfire, V12 No 2, June 2003