The balance between liquid and ice in clouds remains a major challenge in climate modeling, largely due to uncertainties in ice-related processes. We investigate the relative importance of four microphysical processes—primary ice nucleation (PIN), secondary ice production (SIP), sedimentation, and transport of ice crystals—for the supercooled liquid fraction (SLF) in mixed-phase clouds using three global climate models: EC-Earth3-AerChem, NorESM2-MM, and ECHAM6.3-HAM2.3. All models identify PIN as the dominant influence on SLF at cold temperatures in high northern latitudes, but diverge elsewhere and for higher temperatures. Implementing a unified SIP parameterization produced varied model responses, revealing fundamental differences in how microphysical processes interact within each model framework. These discrepancies suggest that each model prioritizes different processes in shaping the cloud phase. Such divergence may limit the reliability of conclusions regarding microphysical processes drawn from any single model.

Abstract Medicanes are high-impact weather systems in the Mediterranean region, associated with floodings, severe damage and human casualties. While there has been continuous effort to understand the dynamic aspects of these systems, little is known about the underlying cloud-scale processes, which cannot be resolved explicitly, consisting a notorious source of uncertainty in atmospheric models. In this study a numerical model with comprehensive Secondary Ice Production (SIP) descriptions is used to investigate the impact of SIP on the evolution of medicane Qendresa. SIP refers to processes that can generate small cloud-ice crystals in concentrations exceeding those produced by primary ice nucleation, promoting cloud glaciation and precipitation. However, its effects on medicane thermodynamics have not been considered before. Our results indicate that improving SIP representation in the model leads to a more accurate prediction of the cyclone track, resulting in improved precipitation patterns, particularly in the regions where extreme precipitation is observed.