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Computation of Atmospheric Concentrations of Molecular Clusters from ab initio Thermochemistry
Published on: April 8, 2020
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Condensed-phase biogenic-anthropogenic interactions with implications for cold cloud formation
Joseph C Charnawskas1, Peter A Alpert, Andrew T Lambe
1Institute for Terrestrial and Planetary Atmospheres, School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA. Daniel.Knopf@stonybrook.edu.
Faraday Discussions
|June 3, 2017
Summary
Anthropogenic secondary organic aerosols (SOA) coatings on soot enhance ice nucleation in clouds, unlike biogenic SOA. This impacts cloud glaciation and climate, especially in mixed-phase and cirrus conditions.
Area of Science:
- Atmospheric Chemistry
- Cloud Physics
- Aerosol Science
Background:
- Secondary organic aerosols (SOA) form from gas emissions and can coat soot particles.
- Understanding SOA-soot interactions is crucial for cloud formation and climate modeling.
Purpose of the Study:
- Investigate SOA-soot interactions and their impact on ice nucleation.
- Determine the role of organic phase state in ice formation.
Main Methods:
- Generated SOA from OH oxidation of naphthalene, α-pinene, longifolene, and isoprene.
- Included sulfate or soot particles in experiments.
- Estimated particle glass transition (Tg) and full deliquescence relative humidity (FDRH) using a numerical diffusion model.
Main Results:
- Longifolene SOA particles were solid-like; biogenic SOA-sulfate mixtures formed core-shell structures.
- Biogenic SOA (with or without sulfate) froze homogeneously.
- α-pinene and naphthalene SOA-coated soot particles acted as ice nuclei (IN) above and below homogeneous freezing temperatures, influenced by SOA viscosity.
Conclusions:
- Biogenic SOA has a limited role in mixed-phase cloud formation, especially with sulfate.
- Anthropogenic SOA coatings on soot can enhance cloud glaciation in mixed-phase and cirrus conditions.
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