When is fire weather extreme enough for active fire spread in Canada?

Area of Science:

• Forest ecology
• Fire science
• Climate change impacts

Background:

• Spread days, characterized by substantial fire growth during extreme weather, are vital for understanding fire regimes.
• Accurate identification of spread days aids in fire forecasting and management.
• Defining thresholds for spread days is critical for fire research and management.

Purpose of the Study:

• To explore the relationship between spread days and fire activity in Canadian forests.
• To identify the specific fire weather conditions conducive to spread days across Canadian Ecozones.
• To estimate the proportion of potential spread days that result in actual fire spread.

Main Methods:

• Spatially and temporally matched daily fire growth data with interpolated daily gridded fire weather data (2001-2021).
• Utilized accumulative area burned density functions to identify fire weather conditions for spread days.
• Analyzed data both annually and seasonally by Canadian Ecozone.

Main Results:

• Median fire-conducive weather conditions are sufficient to support active fire growth.
• An average of 22-30% of potential spread days are realized in actual fire spread across Canadian Ecozones.
• Identified thresholds for extreme fire weather necessary for spread day occurrence.

Conclusions:

• Moderate fire-weather conditions play a significant role in substantial fire growth.
• Understanding the realization rate of potential spread days is key for effective fire management strategies.
• This research contributes to understanding novel fire regimes under changing climate and human influences.