| Description: |
Atmospheric aerosols play key roles in numerous atmospheric processes. They affect human health, are substrates and components for atmospheric chemistry, and via their contribution to clouds affect the water cycle and the energy balance of the planet. The role of aerosols in these processes involves large uncertainty and this partly comes from an incomplete understanding of the aerosol phase state in the atmosphere. In fact, as aerosols travel through the atmosphere they may be exposed to temperature and humidity conditions that alter their properties. Although some of the mechanisms involved such as the deliquescence of soluble particles and the nucleation of cloud droplets are reasonably well understood. Others, like hygroscopic growth below deliquescence and heterogeneous ice nucleation remain poorly understood. This thesis aims to fill some of these knowledge gaps. For clarity, the report is thematically separated between Pre-Deliquescence that has contributed to three published papers (Papers I, II and III) and Ice Nucleation. Ice Nucleation involves significant instrumentation development and has contributed to one measurement report (Paper IV) and one technical paper presenting the developed instrument (Paper V). I. Pre-Deliquescence Soluble particles are characterized by their ability to dissolve into liquid water. They take part in unique processes such as their complete solvation into brine droplets below water saturation (deliquescence); and their surface solvation into thin liquid films below deliquescence (pre-deliquescence). The transition from solid soluble particles to liquid droplets is typically captured by Köhler theory which describes a modified equilibrium vapor pressure due to (i) mixing entropy (Raoult’s law) and (ii) droplet geometry (Kelvin effect). However, this description omits the existence of a pre-deliquesced state. Therefore we develop a more complete model that accounts for interfacial forces giving rise to predeliquescence, in a manner akin to surface melting. The validity of ... |
| Relation: |
Castarède, D., & Thomson, E. S. (2018). A thermodynamic description for the hygroscopic growth of atmospheric aerosol particles. Atmospheric Chemistry and Physics, 18(20), 14939-14948. ::doi:: 10.5194/acp-18-14939-2018; Kong, X., Castarède, D., Boucly, A., Artiglia, L., Ammann, M., Bartels-Rausch, T., . & Pettersson, J. B. (2020). Reversibly physisorbed and chemisorbed water on carboxylic salt surfaces under atmospheric conditions. The Journal of Physical Chemistry C, 124(9), 5263-5269. ::doi:: 10.1021/acs.jpcc.0c00319; Kong, X., Castarède, D., Thomson, E. S., Boucly, A., Artiglia, L., Ammann, M., . & Pettersson, J. B. (2021). A surface-promoted redox reaction occurs spontaneously on solvating inorganic aerosol surfaces. Science, 374(6568), 747-752. ::doi:: 10.1126/science.abc5311; Brasseur, Z., Castarède, D., Thomson, E. S., Adams, M. P., Drossaart van Dusseldorp, S., Heikkilä, P., . & Duplissy, J. (2021). Measurement report: Introduction to the HyICE-2018 campaign for measurements of ice nucleating particles in the Hyytiälä boreal forest. Atmospheric Chemistry and Physics Discussions, 1-46. ::doi:: 10.5194/acp-2021-744; Castarède D, Brasseur Z, Wu Y, Kanji ZA, Bilde M, Stratmann F, Swietlicki R, Svenningsson B, Sierau B, Stetzer O, Nguyen QT, Pettersson JBC, Duplissy J & Thomson ES. Development of the Portable Ice Nucleation Chamber PINCii. Manuscript for submission to Atmospheric Measurement Techniques.; http://hdl.handle.net/2077/69972 |