Advancing Aerosol Chemical Characterization and Vertical Profiling Over the Southern Great Plains via Integrated Uncrewed Aerial Sampling and Aerosol Mass Spectrometry Analyses

CHRISTOPHER NIEDEK, Fan Mei, Wenqing Jiang, Justin Trousdell, Maria Zawadowicz, Beat Schmid, Qi Zhang, University of California, Davis

     Abstract Number: 176
     Working Group: Aerosol Chemistry

Abstract
Uncrewed aerial systems (UAS) help fill gaps in atmospheric observations that exist between traditional, crewed aircraft and ground-based measurement campaigns. Recent advances in UAS technology, particulate matter (PM) sampling, and offline analytical techniques have greatly expanded the potential of UAS to complement other PM measurement modalities. This study utilizes UAS and ground-based instrumentation to examine PM chemistry aloft (e.g. within the boundary layer) versus at ground level and across seasons at the Southern Great Plains atmospheric observatory (SGP). UAS meteorological and PM chemical data reveal key differences in PM characteristics across seasons, reflecting seasonally different emission sources and atmospheric transformation processes. For example, nitrogen-containing organic PM, noted in prior studies examining aerosols at SGP, are similar in winter and early summer but exhibit a clear change in source during late summer. Additionally, comparisons between UAS PM data and ground-based aerosol chemical speciation monitor (ACSM) data underscore the importance of sampling altitude and planetary boundary layer height when examining PM chemistry. In winter, when UAS sampling altitudes were largely above the boundary layer, PM collected by UAS have significantly higher contributions from organic aerosols compared to concurrent ACSM measurements, where inorganic species (e.g. nitrate, sulfate) constitute a greater proportion of total PM mass. Furthermore, UAS samples collected entirely above the boundary layer are also significantly more oxidized than those collected partially within the boundary layer, even during the same months. This work highlights the utility of UAS to complement established PM measurement techniques and to investigate vertical differences in PM chemistry that can be difficult to capture using other methods.