Examination of Airborne-Based Smoke Marker Ratios from Wildfires in the Western U.S. during the WE-CAN Study

Biomass burning is one of the main sources of water-soluble organic carbon (WSOC) and organic carbon (OC) aerosols. Therefore, it is important to be able to determine the contribution of biomass burning to the WSOC or OC concentrations. Smoke marker measurements provide one of the most common methods to make this determination. The key to this approach is that the ratio of the smoke marker to the total WSOC or OC concentration must be known at the source. But there is still much uncertainty in these smoke marker ratios, especially for biomass burning emissions from prescribed burning and wildfires. Therefore, as part of the WE-CAN (Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption and Nitrogen) Study we collected smoke marker data from aboard the C-130 aircraft as it flew through smoke from wildfires occurring in the Western U.S. in July-August 2018. Results were obtained by coupling one Particle-into-Liquid Sampler (PILS) with a Total Organic Carbon analyzer for real-time measurement of WSOC and a second PILS to a fraction collector to provide off-line samples for smoke marker analysis by high-performance anion-exchange chromatography with pulsed amperometric detection. Airborne results from these measurements for a number of different wildfires will be presented. Smoke marker ratios from controlled laboratory burn source samples collected at the Fire Science Lab in Missoula, MT during the FLAME (Fire Science at Missoula Experiment) studies as well as samples collected from various prescribed burns and wildfires across the U.S. will be compared to the results from the WE-CAN measurements. How parameters such as aging and fuel type might play a role will also be discussed.