Enhanced Glaciation of Arctic Mixed-Phase Stratiform Clouds by Turbulence

Turbulence is a key factor in controlling the life cycle and phase partitioning of Arctic mixed-phase clouds. Investigating its impact on cloud microphysics is crucial for understanding the role of Arctic clouds in radiative balance and precipitation. To analyze the role of in-cloud turbulence in Arctic mixed-phase clouds, this study employs an idealized large eddy simulation to numerically simulate a mixed-phase stratiform cloud observed on 10 October 2004, characterized by supercooled liquid water at cloud top and continuous snowfall. The simulation explores cloud phase partitioning under varying turbulence intensities and ice-nucleating particle (INP) concentrations. The results show that stronger turbulence and higher INP concentrations both enhance the cloud glaciation. When INP concentrations are low, the cloud is dominated by liquid water; stronger turbulence can increase the proportion of mixed-phase environments, with the number of mixed-phase clusters decreasing as their scale increases. In clouds with sufficiently high INP concentration, stronger turbulence results in higher occurrence frequency and larger scale of pure ice clusters, which is because the enhancement of turbulence-induced ice nucleation and growth outweighs its impact on liquid-ice mixing. These findings highlight that the observed microphysical properties of Arctic clouds are highly related to the strength of turbulence, and it is necessary to quantify its impact on both glaciation and mixing for understanding the observed cloud phase partitioning.