MONITORING FIRE ACTIVITIES IN THE BOREAL ECOSYSTEM

Forest fire is a major disturbance to the boreal ecosystem and may int eract with climate change. Unfortunately, we have relatively little kn owledge regarding fire activities in the boreal ecosystem. This study investigates the extent and dynamics of the forest fires occurred in a nd around the Boreal Ecosystem-Atmosphere Study (BOREAS) region during summer 1994, an active fire season on record. The statistics of fire activities were obtained from advanced very high resolution radiometer (AVHRR) (aboard NOAA 11) data employing two satellite-based remote se nsing techniques that were designed particularly for monitoring boreal forest fires. Active fires and burned area are estimated using single -day images and 10-day clear composites. Such basic fire attributes as the area and period of burning extracted from the satellite data are compared against the ground reports made by the fire management agenci es in Saskatchewan and Manitoba, Canada. Overall, there were 99 fires of a total burning area of approximately 2 million ha found over an ar ea of 800 x 700 km(2) around the BOREAS study region in summer 1994. A greement in the area of burning is good between the surface observatio ns and satellite-based estimation using single-day images but poor usi ng the composite data that suffer from various uncertainties. The majo rity (87%) of the ground-reported fires were detected by satellite; th e satellite also identified some fires missed by the ground observers. Most fires in 1994 occurred in the transitional forest to the north a nd northwest of the BOREAS region. Regarding to the monitoring of fire evolution, the daily satellite detection approach can be as effective as or even more effective than ground observations, provided that clo ud cover does not occur persistently. The smoke of the fires had an im pact on some BOREAS flux measurements.