Understanding Secondary Organic Aerosol (SOA) Formation over the Southeast USA in the Context of the DOE AMF3 Field Measurements at the Bankhead National Forest (BNF)

MANISHKUMAR SHRIVASTAVA, Brian Gaudet, Alla Zelenyuk, Jerome Fast, Sijia Liu, Sergey Nizkorodov, Celia Faiola, Gregory W. Vandergrift, Zezhen Cheng, Swarup China, Pacific Northwest National Laboratory

     Abstract Number: 396
     Working Group: Aerosol Chemistry

Abstract
The Southeast U.S. is a well-known hotspot for biogenic emissions and secondary organic aerosol (SOA) formation, influenced by dynamic interactions between natural and anthropogenic sources. The recent deployment of the Department of Energy’s third Atmospheric Radiation Measurement Mobile Facility (AMF3) at Bankhead National Forest (BNF) in Alabama provides a unique opportunity to study these processes through long-term, continuous measurements of aerosol, gas-phase, and meteorological properties.

In this study, we use the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to investigate SOA formation over the Southeast U.S., with a focus on the BNF site. Our simulations resolve the formation of isoprene epoxydiol (IEPOX)-SOA driven by interactions between biogenic isoprene and anthropogenic sulfate, incorporating updated parameterizations based on recent laboratory studies. Additionally, we explore how acyclic terpenes emitted by stressed vegetation influence SOA formation compared to cyclic terpenes from healthy plants. By including updated SOA yields, volatility, and viscosity differences between acyclic and cyclic terpenes, we estimate their impacts on SOA mass and cloud condensation nuclei (CCN) formation.

We also assess the potential of AMF3 observations to constrain and evaluate key SOA processes within WRF-Chem. This integrated approach aims to reduce uncertainties in aerosol-cloud interactions and improve our predictive understanding of atmospheric composition over the SE USA.