Speaker: Miguel Hilario
In July 2026, Canadian wildfire smoke impacted much of the Midwest and East Coast, exposing millions of people to hazardous-level air quality. Direct measurements of these extreme pollution events are critical to understand their atmospheric and health impacts, validate satellite retrievals, and improve model predictions of these kinds of events in the future. The University of Wisconsin–Madison Space Science and Engineering Center Portable Atmospheric Research Center (SPARC) is a mobile research laboratory with remote sensing profiling and in situ instruments that simultaneously measure properties of aerosols (i.e., particulate matter), radiation, moisture, clouds, and wind in the troposphere. Measurements of the 2026 Canadian wildfire smoke event were made in Madison, Wisconsin by the SPARC suite of instruments, including a Micro-Orifice Uniform Deposit Impactor (MOUDI), a High Spectral Resolution Lidar (HSRL), an Atmospheric Emitted Radiance Interferometer (AERI), and a doppler wind lidar. Chemical analysis of size-resolved particulate matter (PM) collected by the MOUDI showed greatly enhanced concentrations of wildfire tracers and a distinct aerosol size distribution peaking between 0.32 and 1 μm, which falls within the aerosol size range that can bypass upper respiratory filters and enter the lower respiratory system. Concentrations of PM with diameters less than 2.5 μm (PM2.5) far exceeded the EPA’s 24-hour PM2.5 guideline (up to 5.5 times) and surpassed a similar 2023 wildfire event (4 times higher peak PM2.5). Aerosol backscatter from the HSRL suggests smoke during the 2026 event underwent limited vertical mixing (< 1 km above ground level) that likely contributed to more extreme surface PM2.5 concentrations compared to smoke during the 2023 event, which was well-mixed up to 4 km.
Livestream link: https://www.youtube.com/watch?v=ulIZqhOuL10
Please note the different than usual date, time, and location.