Ice Nucleating Particle Production from Wildfires

Wildfires have been shown to be a potential source of ice nucleating particles (INPs). INPs can modify cloud properties and precipitation processes, but have not been characterized well in elevated smoke plumes. The Western Wildfire Experiment for Cloud Chemistry, Aerosol Absorption, and Nitrogen (WE-CAN) sampled aerosol particle and gas phase compositions in numerous plumes in the western United States with the NSF/NCAR C-130 aircraft based out of Boise, Idaho during July-August 2018. INP measurements in the immersion freezing mode were collected in real time with a Continuous Flow Diffusion Chamber (CFDC) and via offline analyses of aerosol filter collections with the Colorado State University Ice Spectrometer (IS). Analyses will compare inside- and outside-plume sampling periods, as well as along-plume evolution of INP properties. To analyze the influence of smoke following its ingestion by clouds, the CFDC also sampled through a counterflow virtual impactor inlet. The chemical composition of INPs and their differences between plumes will be inferred from their relation to online aerosol chemistry differences and determined directly via electron microscopy analysis of online-collected INPs. The data will provide insights into the effects of fire properties, fuel type, and plume aging on INPs from wildfires in the Western U.S.