Forest Fire Detection

Forest fire activity around the BOREAS site in 1994: Yellow
represents fires detected by ground observation, blue represents extinguished fires detected using 10-day composite data, and red represents active fires using single-day AVHRR images. White represents pixels identified as fires by the two satellite algorithms. NSA denotes the northern study area, and SSA the southern study area of the BOREAS site.

Forest fire detection

A fire detection (hotspot) algorithm was developed that exploits the infrared channels (2-5) from AVHRR [7]. The algorithm is based on the framework of Kaufman et al. [8] with modifications for the NOAA-14/AVHRR sensor. New tests are also introduced to account for the unique environmental and wildfire characteristics of boreal forests. The algorithm consists of two major steps: marking potential fire pixels using the strong thermal signal in the mid-infrared channel (3.7 ?m), then removing false fires using a series of threshold tests (Fig.1). Threshold tests were optimised to detect the majority of real fires, while removing as many false fires as possible. Thresholds were chosen following a trial-and-error approach based on a 1,200 by 1,200 km training data set. Histogram analyses of reflectance and brightness temperature corresponding to burning and non-burning pixels provided an effective means of obtaining optimised values.
The hotspot algorithm was applied to archived single-date GEOCOMP composites for the years 1994-1997, producing a daily fire mask for all of Canada. In summer, 1998, the algorithm was applied operationally. Images showing active fires and smoke were generated within 24 hours of satellite reception, and sent to Canadian fire management agencies and media. Comparing the 1994 and 1995 hotspot locations to provincial fire surveys, the algorithm was found to detect the vast majority (> 90%) of fires larger than 300 ha. Within individual burns, however, the distribution of hotspots is patchy due to limited satellite revisit frequency and obscuring by cloud (Fig. 2). Consequently, the cumulative area of all hotspot pixels detected during each summer was, on average, about 30% less than estimates based on traditional reconnaissance. To account for these missed burned patches, a novel burned area mapping technique was proposed.

Wild fires are a major disturbance to the boreal ecosystem and contribute to the increase in trace gases that causvariations in climate. Fire also deplete timber

resources so that monitoring forest fires is a critical aspect of sustainable forest management. However, conventional ground-based
fire detection techniques are severely limited because they can only cover small areas. For a country the size of Canada, a large-area monitoring capability would provide a definite advantage.

A recent pilot study at CCRS has demonstrated that daily satellite identification of forest fires across the Canadian landmass is feasible. Researchers in Environmental Monitoring have developed preliminary algorithms using NOAA/AVHRR data to measure forest fires. Active fires are primarily detected using AVHRR channel 3, while extinguished fires are assessed using the 10-day clear-sky composites of AVHRR channels 1 and 2. The performance of the remote sensing algorithms was evaluated against ground-based fire observation data obtained by provincial fire agencies in Saskatchewan and Manitoba. The test site, which is the study region of the Boreal Ecosystem-Atmosphere Study (BOREAS), spans an area of 1000 X 1000 km2 across the two provinces.

During the 1994 fire season, about 70 fires were observed over the study site: ground observations reported 76 and satellite observations reported 66. The difference in reporting is due largely to the ambiguity created by fire clustering. The total burning area estimated by the two approaches is around 1.8 and 1.9 million hectares. Statistics for the bulk size of fires are
comparable for both ground and satellite observations, but comparison is poor for the size of individual fires. The satellite-based technique monitors the evolution of each fire fairly well, within the limitations imposed by cloud cover and generally reports the starting dates of fires earlier than those reported by ground observations. This provides a better opportunity to suppress the fires before they run out of control.

Based on these promising early results, developing a space-borne operational system for nation-wide fire monitoring is now possible. Further studies will provide more timely and complete information on fire and its emissions, and the interaction between fires and weather.

For more information, please contact:

Zhanqing Li
Applications Division, CCRS

Bearskin Lake, Ontario
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Lake Nipigon, May 3, 1999
Lake Nipigon, Ontario
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Lake Winnipeg, May 2, 1999
Lake Winnipeg, Manitoba
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Forest Fires, 1999

Given the size of Canada, the use of remote sensing data is considered to be the only cost effective way to achieve a comprehensive overview of forest fire activity in Canada in near-real time. These images were acquired as part of the Fire Monitoring, Mapping and Modeling System (Fire M3) an initiative of the Canada Centre for Remote Sensing and the Canadian Forest Service.

A dry spring and human carelessness has resulted in more than 65 forest fires in Manitoba. About 400 residents of three small towns clustered on the northeast shore of Lake Winnipeg have been forced to flee their homes.

Lake Nipigon, May 4 1999
Beardmore, Ontario
Full image (77kb jpg)

In Northern Ontario, 54 fires broke out over the weekend of May 1, forcing for a time the closing of highways in the Temagami and Kenora areas. A huge forest fire has forced the evacuation of the town of Beardmore located on the southeast shore of Lake Nipigon. About 300 residents from the town have fled to Geraldton, 80 kilometres to the east.

Sources: Winnipeg Free Press and CBC News online.

Kluane Lake, Yukon
Great Bear Lake, NWT
Great Slave Lake, NWT
Kasba Lake, NWT
Salmon Arm, B.C.
Williston Lake, B.C.
Swan Hills, Alta.
Lake Athabasca, Sask.
Reindeer Lake, Sask.
S. Indian Lake, Man.
James Bay, Ont.
Lake Nipigon, Ont.
James Bay, Que

Canadian Forest Fires, 1998

These are time series of NOAA AVHRR satellite images acquired over areas of Canada that clearly show the extent of forest fires. The hot spot of a fire is marked as a red dot and the backgroud is a false-color composite using AVHRR channel 1 (visible) and channel 2 (near IR) reflectance measurements.

AVHRR data are received at the Prince Albert satellite receiving station. Raw data are sent to CCRS, where they are first calibrated. A fire detection algorithm, developed by scientists in the Environmental Monitoring Section is then applied, and the images can now be used by forest fire management agencies for forest fire monitoring and supression.

Location Map (11Kb)
August 20, 1998 (26Kb)
August 17, 1998 (39Kb)
August 16, 1998 (31Kb)
August 15, 1998 (31Kb)
July 20, 1998 (43Kb)
July 5, 1998 (43Kb)
July 4, 1998 (18Kb)
July 3, 1998 (23Kb)
July 3, 1998 (10Kb)
June 6, 1998 (29Kb)
June 2, 1998 (33Kb)
June 1, 1998 (13Kb)

Kluane Lake, Yukon