A Note on Aerosol Processing by Droplet Collision‐Coalescence

Hoffmann, Fabian; Feingold, Graham (2023): A Note on Aerosol Processing by Droplet Collision‐Coalescence. Geophysical Research Letters, 50 (11). ISSN 0094-8276

Abstract

The processing of aerosol by droplet collision-coalescence is analyzed in three-dimensional simulations of drizzling stratocumulus using a Lagrangian cloud model for the representation of aerosol and cloud microphysics. Collision-coalescence processing is shown to create a characteristic bimodality in the aerosol size distribution. We show that the large-scale dynamics of the stratocumulus-topped boundary layer are key to understanding the amount of time available for collision-coalescence processing. The large-scale dynamics enable aerosol particles to repeat a cycle of droplet condensation, collision-coalescence, and evaporation, which causes a steady increase in aerosol size. This process is continued until the aerosol grows so large that droplet growth is substantially accelerated and multiple collisions occur within one cycle, forming precipitation-sized droplets that are lost to the surface, including the aerosol. An analytical relationship is derived that captures the fundamental shape of the processed aerosol size distribution.

• Doc-Type: Article (LMU)
• Organisational unit (Faculties): 17 Physics
• DFG subject classification of scientific disciplines: Natural sciences
• DFG: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 435878013
• DFG: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) - 491502892