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Mapping wildfires in Canada with Landsat MSS to extend the National Burned Area Composite (NBAC) time series back to 1972
Abstract
Background: Burned area mapping has improved globally with the advent of satellite imaging; however, few studies have taken advantage of the Multi-Spectral Scanner (MSS) in early Landsat satellites, which started acquiring data 10 years earlier than the more commonly used Thematic Mapper (TM). Aims: To expand Canada’s National Burned Area Composite (NBAC) annual time series back to 1972 using MSS data and report annual statistics and national trends for 1972-2022. Methods: For each candidate fire location, pre- and post-fire image composites were created using an improved collection of MSS data available from the Google Earth Engine (GEE). A Normalized Difference Vegetation Index (NDVI) difference image was adaptively thresholded to extract burned areas, which were then vectorized. To assess accuracy, MSS fire polygons were compared to TM in a year of overlap (1986). Key results: Compared to TM, MSS polygons overestimate burned area by 5.6% when the relativized differenced NDVI was used. Significant upward trends were detected for number of fires > 200 ha, fire season length, and mean duration of fires. Conclusions: MSS is a valuable data source for retrospective mapping of boreal and temperate forest fires where data from finer-resolution sensors like TM are lacking. Implications: After the addition of MSS-mapped fires, NBAC is the longest satellite-based time series of annual burned area from individually mapped fires in any country in the world.
WF24138 Accepted 23 November 2024
© CSIRO 2024
