ect of scan angle on AVHRR ® re detection accuracy in interior Alaska

SomeAVHRR® re 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 e€ ects of scan angle on the Normalized Di€ erence Vegetation Index. However, excluding high scan angle pixels reduces the temporal resolution of an AVHRR ® re detection system, especially at high latitudes. High scan angle pixels may be less obscured by smoke compared to near-nadir pixels. We tested the e€ ect of scan angle on AVHRR ® re detection by comparing scan angle classes of less than and greater than 25ß from sixteen AVHRR images of interior Alaska. At scan angles under 25ß , 35/86 (40%) of ® re observations were detected. At scan angles over 25ß , 24/53 (45%) of ® re observations were detected. For interior Alaska, where cloudy, low-fuel conditions exist, and 8± 12 AVHRR images are available daily, we recommend not excluding high scan angle pixels for wild® re detection.