Drivers of biogenic secondary organic aerosol from the past to the future
Year: 2026
Type: article
Abstract: Biogenic secondary organic aerosol (SOA) makes up a substantial fraction of atmospheric fine particulate mass, with implications for climate and human health. However, its chemical formation processes remain poorly understood and are often oversimplified in 3D models. Recent studies have found that the peroxy radical (RO 2 ) isomerization and the RO 2 accretion reactions (RO 2 + RO 2 ) can lead to SOA formation. We expand the RO 2 chemical mechanism in the Community Earth System Model version 2 to include these two additional pathways for biogenic SOA formed through the OH oxidation of volatile organic compounds (VOCs). Using this mechanism, we quantify the contribution of each RO 2 pathway to biogenic SOA formation and examine how these contributions evolve from the pre-industrial (PI) to present-day (PD) and future (F). We find that in PD conditions, RO 2 isomerization accounts for nearly half of monoterpene SOA, while the contribution from RO 2 + RO 2 pathways is minor. From PI to F, the RO 2 fate varies in response to atmospheric NO x levels and climate, but the contribution from RO 2 isomerization is consistently high for monoterpenes, underscoring the importance of representing this pathway in SOA parameterizations. Total biogenic SOA formed through OH oxidation decreases by 41 % from PI to PD and increases by 112 % from PD to F. This evolution from PI to F is largely driven by changes in biogenic VOC emissions, rather than shifts in chemistry or thermodynamic partitioning. Our results highlight the need to better constrain RO 2 pathways for SOA formation through laboratory studies and represent this RO 2 chemistry in SOA modeling.
Authors: Yang Shi, Colette L. Heald, Jesse H. Kroll
Language: English
Subfield: Atmospheric Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
SDG: Climate action
Open Access status: gold
Estimated APC paid: $1,725
OpenAlex ID: W7140628324