Airborne characterization of aerosol particles and gases emitted from the 2025 Canadian wildfires at Red Lake

Wildfires are both a consequence of and a contributor to extreme weather events. Their increasing frequency and intensity significantly impact the atmosphere by virtue of the aerosol particles and gases they release and the radiative forcing impact of those atmospheric injections. In-situ measurements of these aerosols are extremely limited. Here, we present results from an aircraft-based field campaign conducted in July 2025, in the vicinity of Red Lake, Ontario, Canada. Fires with both flaming combustion and lower radiative power following rainfall were sampled. The aerial platform was the National Research Council Canada’s Twin Otter aircraft. The Twin Otter aircraft is a specialized and customizable research platform equipped with a variety of scientific instruments and sensors.

Gaseous measurements including greenhouse gases carbon dioxide (CO₂), methane (CH₄) and water vapor (H₂O) were taken. Auxiliary data included aircraft state (aircraft location, altitude, and orientation) and atmospheric state (temperature, pressure and dew point). Particulate measurements including particle size distributions (PSDs), concentrations, single scattering albedos (SSA) and refractory black carbon (rBC) concentrations are reported. In addition, the number of non-rBC particles observed after thermo-denuding – representing ash or char particles – was measured in a dedicated experiment.

During these dedicated flights, we sampled both aerosols and gases at varying distances from the source and from directly above the fire to several hundred kilometers downwind. Preliminary results will include the properties and characterization of wildfire aerosols and GHGs at different distances from the fire source.