Particle-resolved simulations of immersion freezing with multi-species ice nucleating particles

Tang, Wenhan

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https://hdl.handle.net/2142/124611 Copy

Description

Title

Particle-resolved simulations of immersion freezing with multi-species ice nucleating particles

Author(s)

Tang, Wenhan

Issue Date

2024-05-03

Director of Research (if dissertation) or Advisor (if thesis)

Riemer, Nicole

Committee Member(s)

• Di Girolamo, Larry
• West, Matthew

Department of Study

Climate Meteorology & Atm Sci

Discipline

Atmospheric Sciences

Degree Granting Institution

University of Illinois at Urbana-Champaign

Degree Name

M.S.

Degree Level

Thesis

Keyword(s)

• Ice Nucleation
• Immersion Freezing

Language

eng

Abstract

Immersion freezing, initiated by an ice-nucleating particle (INP) in a supercooled aqueous droplet, has been recognized to play an important role in the formation of ice crystals within clouds. The efficiency of the ice nucleation process depends strongly on the chemical composition of the INPs. Furthermore, INPs can exhibit various mixing states, ranging from external mixtures to internal mixtures, with diverse distributions of chemical species across the particle population. Here, we investigate the impact of the aerosol mixing state on immersion freezing using the stochastic particle-resolved aerosol model (PartMC). We have extended PartMC with a time-dependent representation of immersion freezing based on the water activity-based immersion freezing model and generalized the freezing model’s formulation to calculate freezing rates of INPs that contain multiple species. An efficient algorithm, based on the binned tau-leaping method, has been developed to enable PartMC to simulate particle-resolved immersion freezing with enhanced computational speed while maintaining accuracy. We analytically derived the limiting behavior for the fraction of droplets that undergo immersion freezing when the INPs are internally mixed compared to externally mixed. The impact on the presence of different species on the frozen droplet fraction is explored through simulation. Our findings indicate distinctly different immersion freezing rates when considering internal and external particle mixtures, which is exacerbated when species with different freezing efficiencies are present.

Graduation Semester

2024-05

Type of Resource

Text

Handle URL

https://hdl.handle.net/2142/124611

Copyright and License Information

Copyright 2024 Wenhan Tang

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