Speaker
Description
Increased anthropogenic activities and industrialization have led to a substantial increase in greenhouse gas emissions and atmospheric aerosol concentrations and caused climate change. Increased aerosol concentration in the atmosphere affects the radiation budget and climate in two distinct ways. First, aerosols cool the atmosphere by directly reflecting incoming solar radiation. Second, aerosol particles act as cloud condensation nuclei, affecting cloud formation and precipitation. Increased aerosol concentration makes the cloud brighter, increases the cloud's lifetime, and further enhances the reflection of the incoming solar radiation. The potential role of these aerosols, which cool the atmosphere, recently gained interest in mitigating climate change. However, due to a lack of understanding of the underlying processes, their impact remains a significant source of uncertainty in predicting future climate change. The effect of aerosol concentration on cloud brightness and lifetime is closely related to the turbulent mixing process between clouds and the surrounding dry air, so-called entrainment and mixing. Throughout the cloud lifecycle, clouds continuously mix with the ambient air, gradually losing the force to ascend through evaporation and eventually dissipating. In addition, distinctive ways of how the entrainment and mixing change the shape of cloud droplet size distribution change the radiative properties of cloud in different ways. This presentation shows the results from a novel large eddy simulation capable of tracking individual cloud droplets and aerosol particles to investigate how the characteristic of the entrainment and mixing process change in cloud life stages, developing, maturing, and dissipating by tracking over 100 shallow cumulus clouds throughout their lifecycle stages. We found that cloud lifetime changes are affected by aerosol number concentration, and the dominant way of changing cloud radiative properties differs in each mixing stage.
References
Lim, J. S., & Hoffmann, F. (2023). Between Broadening and Narrowing: How Mixing Affects the Width of the Droplet Size Distribution. Journal of Geophysical Research: Atmospheres, e2022JD037900.
| Keywords | Cloud-Aerosol interaction, Large eddy simulation, Entrainment and Mixing |
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