The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles
<p>In marine environments, sea spray aerosol (SSA) particles have been found to contain surface-active substances (surfactants) originating from the sea surface microlayer. These surfactants can lower the surface tension of the SSA particles, facilitating their activation to cloud droplets. Th...
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Copernicus Publications
2025-01-01
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| Series: | Atmospheric Chemistry and Physics |
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| author | J. Kleinheins N. Shardt U. Lohmann C. Marcolli |
| author_facet | J. Kleinheins N. Shardt U. Lohmann C. Marcolli |
| author_sort | J. Kleinheins |
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| description | <p>In marine environments, sea spray aerosol (SSA) particles have been found to contain surface-active substances (surfactants) originating from the sea surface microlayer. These surfactants can lower the surface tension of the SSA particles, facilitating their activation to cloud droplets. This effect is not considered in classical Köhler theory, which assumes droplets to be homogeneous with a surface tension of pure water. In this study the cloud condensation nuclei (CCN) activity of SSA particles calculated with classical Köhler theory is compared to a more complex calculation that considers bulk–surface partitioning, surface tension lowering, and liquid–liquid phase separation. The model approach presented here combines the multi-component Eberhart model for surface tension with the monolayer model and an activity model (Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients, AIOMFAC). This combination allows for calculating Köhler curves of surfactant-containing particles with a large number of compounds for the first time. In a sensitivity study we show that organic compounds can be categorized into weak, intermediate, and strong surfactants for CCN activation based on their separation factor in water <span class="inline-formula"><i>S</i><sub>1<i>i</i></sub></span> and their pure component surface tension <span class="inline-formula"><i>σ</i><sub><i>i</i></sub></span>. For a quaternary model system of SSA particles, it is shown that high content of hydrophobic organic material (i.e. strong surfactants) in Aitken mode particles does not necessarily prevent good CCN activation but rather facilitates effective activation via surface tension lowering. Since common climate models use parameterizations that are based on classical Köhler theory, these results suggest that the CCN activity of small SSA particles might be underestimated in climate models.</p> |
| format | Article |
| id | doaj-art-384abe392f5f440fb66e5eec4f4e4b15 |
| institution | Kabale University |
| issn | 1680-7316 1680-7324 |
| language | English |
| publishDate | 2025-01-01 |
| publisher | Copernicus Publications |
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| series | Atmospheric Chemistry and Physics |
| spelling | doaj-art-384abe392f5f440fb66e5eec4f4e4b152025-01-23T10:19:20ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-01-012588190310.5194/acp-25-881-2025The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particlesJ. Kleinheins0N. Shardt1U. Lohmann2C. Marcolli3Institute for Atmospheric and Climate Science, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, SwitzerlandDepartment of Chemical Engineering, Norwegian University of Science and Technology (NTNU), 7491 Trondheim, NorwayInstitute for Atmospheric and Climate Science, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, SwitzerlandInstitute for Atmospheric and Climate Science, ETH Zurich, Universitätsstrasse 16, 8092 Zurich, Switzerland<p>In marine environments, sea spray aerosol (SSA) particles have been found to contain surface-active substances (surfactants) originating from the sea surface microlayer. These surfactants can lower the surface tension of the SSA particles, facilitating their activation to cloud droplets. This effect is not considered in classical Köhler theory, which assumes droplets to be homogeneous with a surface tension of pure water. In this study the cloud condensation nuclei (CCN) activity of SSA particles calculated with classical Köhler theory is compared to a more complex calculation that considers bulk–surface partitioning, surface tension lowering, and liquid–liquid phase separation. The model approach presented here combines the multi-component Eberhart model for surface tension with the monolayer model and an activity model (Aerosol Inorganic–Organic Mixtures Functional groups Activity Coefficients, AIOMFAC). This combination allows for calculating Köhler curves of surfactant-containing particles with a large number of compounds for the first time. In a sensitivity study we show that organic compounds can be categorized into weak, intermediate, and strong surfactants for CCN activation based on their separation factor in water <span class="inline-formula"><i>S</i><sub>1<i>i</i></sub></span> and their pure component surface tension <span class="inline-formula"><i>σ</i><sub><i>i</i></sub></span>. For a quaternary model system of SSA particles, it is shown that high content of hydrophobic organic material (i.e. strong surfactants) in Aitken mode particles does not necessarily prevent good CCN activation but rather facilitates effective activation via surface tension lowering. Since common climate models use parameterizations that are based on classical Köhler theory, these results suggest that the CCN activity of small SSA particles might be underestimated in climate models.</p>https://acp.copernicus.org/articles/25/881/2025/acp-25-881-2025.pdf |
| spellingShingle | J. Kleinheins N. Shardt U. Lohmann C. Marcolli The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles Atmospheric Chemistry and Physics |
| title | The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles |
| title_full | The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles |
| title_fullStr | The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles |
| title_full_unstemmed | The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles |
| title_short | The surface tension and cloud condensation nuclei (CCN) activation of sea spray aerosol particles |
| title_sort | surface tension and cloud condensation nuclei ccn activation of sea spray aerosol particles |
| url | https://acp.copernicus.org/articles/25/881/2025/acp-25-881-2025.pdf |
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