SOACAVE

SE U.S. Organic Aerosol Composition and Volatility

16 June 2025 - 30 September 2026

Lead Scientist: Joel Thornton

Observatory: AMF

The goals of this campaign are to measure ambient organic aerosol molecular composition and volatility at the ARM Mobile Facility 3 site in Bankhead National Forest during summer when biogenic volatile organic compound emissions from forest vegetation are at their highest. Organic carbonaceous material, especially from biogenic volatile organic compound (BVOC) oxidation, is often one of the dominant components of atmospheric submicron particles, especially in forested regions. Measurements of molecular composition and volatility can elucidate important precursors and formation mechanisms which can be used to improve simulation of this natural source of aerosol particles in earth system and cloud resolving models.

We will use the University of Washington Filter-Inlet for Gases and Aerosols (FIGAERO) coupled to a high-resolution time of flight chemical ionization mass spectrometer (HR-ToF-CIMS) to measure organic aerosol composition and volatility. This instrument will be supplied by the PI and collaborators. The FIGAERO-HR-ToF-CIMS achieves online, in-situ measurements of organic aerosol composition and volatility, both through gas-particle partitioning estimates and relationships between vapor pressure and desorption temperature, approximately every hour (24 samples per day) across a wide range of organic compounds. The molecular composition and effective volatility of desorbed compounds is determined by post-campaign analysis of the HR-ToF-CIMS spectral time series. We have shown with previous FIGAERO-HR-ToF-CIMS measurements in the Southern Eastern U.S. that these observations enable identification and quantitative speciation of multiple VOC precursor and oxidation pathway pairings in a BVOC impacted region.