A "large territory to cover" is putting it mildly. Canada's Northwest Territories span more than 1.3 million square kilometers (more than 500,000 square miles) and has an estimated population of 45,000. Approximately 46% of the NWT (~614,000 square kilometers) is forested, and 112,600 square kilometers (approximately 70,000 square miles) of that forestland lies within the boundaries of the South Slave Administrative Region.
"If I were to go out on a detection patrol, usually in a small aircraft, a round trip from my community of Fort Smith to the southeast corner of our region is about 700 miles," Seymour said. "We often don't go that far, but occasionally we'll need to go and have a look to confirm detections that we've noticed."
FIRMS hotspot detection data make this task easier.
"Fire detection is one of the primary things we use FIRMS for," he said. "Basically, we'll go out and physically confirm that a notification we've received is indeed a fire, and ensure they are not possibly false hits."
The vast majority of the fires that start in the NWT are caused by lightning and, in general, the fire season in the South Slave Region runs from around May 1 to October 1. However, Seymour notes that recent fire seasons have started earlier and lasted longer, with active fire activity occurring until the end of October, when snow stays on the ground and finally ends the season.
In addition to lasting longer, fire seasons in the NWT are getting more intense. In fact, the 2023 fire season was particularly noteworthy. In mid-August, there were 236 active fires in the NWT and the threat they posed to communities led the government to declare a territory-wide state of emergency, prompting the biggest evacuation operation in NWT history.
"[2023 was] an unprecedented fire season, certainly in the 40 years that I've lived in the Northwest Territories," he said. "I've never seen anything like it, both in terms of the general extreme drought conditions and the actual fire weather we experienced in those conditions."
A busy fire season can make confirming a deluge of hotspot detections difficult, said Seymour, who noted that in 2023, there were moments when he and his colleagues were receiving 20 to 30 fire notifications an hour. Data from FIRMS helped Seymour and his colleagues decide which fires to prioritize.
Using FIRMS in the Northwest Territories
"The first thing we'll often do is pull up our values database, which shows the locations of structures (e.g., cabins), industrial facilities (e.g., mines), etc. and overlay it with Moderate Resolution Imaging Spectroradiometer (MODIS) or Visible Infrared Imaging Radiometer Suite (VIIRS) detections," he said. "If we receive a notification that's close to a structure, we will prioritize that location and go have a look and assess the situation."
If Seymour and his fellow team members can't immediately get out to confirm a notification, they'll sometimes turn to FIRMS detection data for help.
"If we notice there's two more hits beside the first in the next day, then there's a good chance that there's an active fire," Seymour said. "We'll then often use [satellite] imagery when available from Landsat or Sentinel-2, whose higher spatial resolution gives us a better chance of seeing smoke. If we see smoke on the imagery at the same location, then it's a pretty sure bet it’s an active fire."
Such use of the FIRMS Fire Map and data not only makes Seymour and his department more efficient, it helps them make the most of their often-limited resources.
"Up here, we don't have a lot of roads going everywhere, so often the only way to go out and see things on the ground is to actually fly out there. More often than not that requires a helicopter, and aviation costs have gone right through the roof," Seymour said. "They've probably more than doubled in the last 10 years. So, having tools [like FIRMS] really helps us keep costs down."
FIRMS Foundations
FIRMS' active fire data are derived from the MODIS and VIIRS instruments, both of which can detect radiated energy from their respective orbits approximately 440 and 515 miles (705 and 830 kilometers) above Earth's surface.
MODIS flies aboard NASA's Terra and Aqua satellites, and the Fire and Thermal Anomalies product generated from it is the foundation of FIRMS active fire products. When MODIS detects a thermal anomaly, which could indicate a wildfire or any significant source of heat, a computer algorithm identifies the center of the one square-kilometer area in which the anomaly is detected. This location is plotted and available to fire crews and wildland managers within three hours of observation, providing an approximate location of a potential wildfire or hotspot.
VIIRS flies aboard the joint NASA-NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) and the Joint Polar Satellite System’s (JPSS) NOAA-20 and -21 satellites. The VIIRS I-band (375 meter) Active Fire product is based on the MODIS Fire and Thermal Anomalies product, which means there is good agreement between the two products. However, VIIRS provides better response for smaller fires and improved mapping of large fire perimeters. Further, the VIIRS 375 m product shows a better response in nighttime observations, when fire activity normally subsides.