Detecting high and low-intensity fires in Alaska using VIIRS I-band data: An improved operational approach for high latitudes

Fire products from Moderate Resolution Imaging Spectroradiometer (MODIS) and Visible Infrared Imaging Radiometer Suite (VIIRS) imagery provide timely information for wildfire detection, monitoring, and characterization at the global scale. However, in Alaskan boreal forest fires, their lower effectiveness in detecting residual fire once the high-intensity fire front has passed limits their practical use for regional or local fire management decisions. Using data acquired during Alaska's 2016 fire season, we analyzed the performance of the MODIS-based MOD14/MYD14, and the more recent VIIRS I-band active fire products. A comparison with the fire perimeter and properties data published by the Alaska Interagency Coordination Center (AICC) shows that both MODIS and VIIRS fire products successfully detect all fires larger than approximately 200-300 ha. For fires smaller than this threshold, the VIIRS I-band product offers higher detection likelihood. To map burn areas containing both low- and high-intensity active fire, we developed the VIIRS I-band Fire Detection Algorithm for High Latitudes (VIFDAHL). We apply this algorithm to regions of known Alaskan boreal forest fires and validate it using events mapped by fire management agencies and detected on closely-timed Landsat imagery. We find that for Alaska, an example of a high-latitude region, VIFDAHL more accurately captures the fire spread, can differentiate well between low- and high-intensity fires, and can detect 30-90% more fire pixels compared to the MODIS and VIIRS global fire products.