Analyzing the Surfactant Effect on Cloud Condensation Nuclei (CCN) Activity Using a Particle-Resolved Aerosol Model
Abstract
The effects of atmospheric aerosols on climate are poorly understood, which leads to uncertainty in predictions of climate change. Aerosol particles, or minute particles suspended in the atmosphere, can change cloud reflectivity, leading to a cooling effect known as the aerosol indirect effect, but the magnitude of this cooling is not well quantified. To evaluate the aerosol indirect effect, we need to know how aerosols act as a cloud condensation nuclei (CCN), absorbing moisture and then growing into a cloud. We use Kohler theory to model whether a particle of a given size and composition has the ability to form a CCN under certain environmental conditions. However, Kohler theory assumes uniform composition within each particle, and that the particle's surface tension is equal to that of water. In reality, many particles contain surfactants (substances that reduce surface tension in liquids) that partition to the droplet's surface and modify the water-uptake tendency of the particle. We analyzed model output from PartMC-MOSAIC, a detailed aerosol model, to quantify the effect of these surfactants on CCN activity. Equations from previous research were coded to take into account the ability of surfactants to alter surface tension and water-uptake tendency of cloud droplets. We applied these new algorithms to model output from PartMC-MOSAIC, which includes specific data about the composition and size of individual particles emitted from an urban plume, and quantified the difference in CCN activity between particles containing surfactants and those without. The results of this study will be used to determine whether it is important to take into account the role of surfactants in climate models to accurately predict the aerosol indirect effect.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2020
- Bibcode:
- 2020AGUFMED0260020D
- Keywords:
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- 0805 Elementary and secondary education;
- EDUCATION