The Organic Contribution to Stratospheric Aerosol Particles Collected during the SABRE 2023 Campaign

Stratospheric aerosols play a critical role in the chemistry of the atmosphere and the climate through heterogeneous chemistry and radiative forcing. While sulfate aerosols in the stratosphere are relatively well-studied, the organic component of stratospheric aerosols remain poorly understood, despite their potential to impact climate and chemistry.

The Stratospheric Aerosol processes, Budget, and Radiative Effects (SABRE) 2023 campaign employed high-altitude aircraft (WB-57) with a payload designed to better characterize stratospheric aerosols. We used a cascade impactor (Mini-MOUDI 135, MSP) to collect aerosol particles between 0.18-3.2 μm aerodynamic diameter for offline analysis. Here we highlight the effectiveness of Computer-Controlled Scanning Electron Microscopy with Energy Dispersive X-ray (CCSEM-EDX) and Scanning Transmission X-ray microscopy paired with near-edge X-ray absorption fine structure (STXM-NEXAFS) to determine stratospheric aerosol composition and morphology. These properties can help constrain aerosol effects on radiative forcing and ozone chemistry. CCSEM-EDX is used to analyze the morphological and elemental properties of atmospheric aerosols on the single particle basis. STXM-NEXAFS uses carbon K-edge spectra to categorize individual stratospheric aerosols into organic carbon, elemental carbon, and inorganic content, which can be used to investigate the mixing state, morphology, and carbon functional group distribution. Preliminary findings from nanospray Desorption Electrospray Ionization (nano-DESI) further reveal molecular-level organic aerosol composition. We show comparative analysis across multiple flights, distinguishing between polar vortex and non-polar vortex air. Finally, we explore the implications of these findings for assessing the chemical and radiative properties of stratospheric aerosols, advancing our understanding of their role in Earth’s atmosphere.