Simulated phase state and viscosity of secondary organic aerosols over China

Abstract T g T g T g, org) agrees well with the value estimated from ambient volatility measurements at an urban site in Beijing. For the spatial distributions of T g, org, simulations show that at the surface the values of T g, org range from ∼ 287  to 305 K, with higher values in northwestern China, where SOA particles have larger mass fractions of low-volatility compounds. Considering water uptake by SOA particles, the SOA viscosity shows a prominent geospatial gradient in which highly viscous or solid SOA particles are mainly predicted in northwestern China. The lowest and highest SOA viscosity values both occur over the Qinghai–Tibet Plateau, where the solid phase state is predicted over dry and high-altitude areas and the liquid phase state is predicted mainly in the south of the plateau with high relative humidity during the summer monsoon season. Sensitivity simulations show that, including the formation of extremely low-volatility organic compounds, the percent time that a SOA particle is in the liquid phase state decreases by up to 12 % in southeastern China during the simulated period. With an assumption that the organic and inorganic compounds are internally mixed in one phase, we show that the water absorbed by inorganic species can significantly lower the simulated viscosity over southeastern China. This indicates that constraining the uncertainties in simulated SOA volatility distributions and the mixing state of the organic and inorganic compounds would improve prediction of viscosity in multicomponent particles in southeastern China. We also calculate the characteristic mixing timescale of organic molecules in 200 m SOA particles to evaluate kinetic limitations in SOA partitioning. Calculations show that during the simulated period the percent time of the mixing timescale longer than 1 h is > 70  % at the surface and at 500 hPa in most areas of northern China, indicating that kinetic partitioning considering the bulk diffusion in viscous particles may be required for more accurate prediction of SOA mass concentrations and size distributions over these areas.

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch

References and Relationships

• Bibliographic citation: Simulated phase state and viscosity of secondary organic aerosols over China ; volume:24 ; number:8 ; year:2024 ; pages:4809-4826 ; extent:18 ; Atmospheric chemistry and physics ; 24, Heft 8 (2024), 4809-4826 (gesamt 18)

Contributors, Places and Time

• Creator: Zhang, Zhiqiang ; Li, Ying ; Ran, Haiyan ; An, Junling ; Qu, Yu ; Zhou, Wei ; Xu, Weiqi ; Hu, Weiwei ; Xie, Hongbin ; Wang, Zifa ; Sun, Yele ; Shiraiwa, Manabu

Further information

• DOI: 10.5194/acp-24-4809-2024
• URN: urn:nbn:de:101:1-2404250414257.724587803599
• Rights: Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 14.08.2025, 10:57 AM CEST