Steven H. Boles

M.S. Natural Resources Management, University of Alaska Fairbanks,1998

Current Positions:  Remote Sensing Analyst, Complex Systems Research Center, University of New Hampshire

email:Stephen.Boles@UNH.edu

Published Arcticles from M. S. Thesis:

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Comparison of Three AVHRR-Based Fire Detection Algorithms for Interior Alaska

ABSTRACT

Three satellite fire detection models (threshold, contextual, and fuel mask) were compared and evaluated using National Oceanographic and Atmospheric Administration (NOAA)-11, NOAA-12, and NOAA-14 Advanced Very High Resolution Radiometer sensor data from interior Alaska.  The fixed threshold model compared the radiant temperature of each pixel to predetermined threshold values.  The contextual model compared the radiant temperature of each pixel to its surrounding (background) pixels.  The fuel mask model is similar to the contextual model, but pixels were tested for fuel availability according to pre-fire vegetation index values.  Fire location data from the Alaska Fire Service was used to assess the accuracy of the fire detection models.  Fire detection accuracy: (a) was highest using the fuel mask model; (b)was lowest using the fixed threshold model; (c)increased as fire size increased; (d)was considerably greater in afternoon images than morning or night images.  Fire detection methods may be less accurate in taiga/tundra regions such as interior Alaska due to landscape heterogeneity and relatively low aboveground fuel.

Effect of scan angle on AVHRR fire detection accuracy in interior Alaska.

ABSTRACT

Some AVHRR fire detection studies have excluded pixels that exceeded an arbitrary scan angle.  This exclusion seems to be based on the distortion of pixels at high scan angles and the well-documented effects of scan angle on the Normalized Difference Vegetation Index.  However, excluding high scan angle pixels reduces the temporal resolution of an AVHRR fire detection system, especially at high latitudes.  High scan angle pixels may be less obscured by smoke compared to near-nadir pixels.  We tested the effect of scan angle on AVHRR fire detection by comparing scan angle classes of less than and greater than 25 degrees from sixteen AVHRR images of interior Alaska.  At scan angles under 25 degrees, 35 of 86 (40 percent) of fire observations were detected.  At scan angles over 25 degrees, 24 of 53 (45 percent) of fire observations were detected.  For interior Alaska, where cloudy, low-fuel conditions exist, and 8 to 12 AVHRR images are available daily, we recommend not excluding high scan angle pixels for wildfire detection.