Do bioaerosols or mineral dust dominate the global population of ice-nucleating particles?

Ice processes in mixed-phase clouds (MPC) are a key source of uncertainty in climate predictions due to complex aerosol-cloud interactions. This study improves a global chemistry-transport model by incorporating advanced laboratory-based parameterizations to assess the contributions of diverse ice nucleating particle (INP) sources: mineral dust (K-feldspar and quartz), marine primary organic aerosols (MPOA), and terrestrial primary biological aerosol particles (PBAP). The results reveal distinct roles for each source: PBAP dominate ice formation at lower altitudes in warmer conditions, particularly in tropical regions and during the Northern Hemisphere summer. Dust-derived INP prevail at high altitudes across all seasons, especially in polar regions and colder temperatures, while MPOA-derived INPs are most influential at low altitudes in the Southern Hemisphere, notably in subpolar and polar areas. The model achieves its highest predictive accuracy when dust and marine aerosols are treated as independent sources of INP, while PBAP, though significant for warm-temperature ice nucleation at low altitudes, contribute less to improving model-observation agreement. These findings underscore the need for explicitly representing dust, marine, and biological aerosols as distinct contributors to ice formation in climate models, offering a pathway to more accurate predictions of cloud processes and their impacts on climate systems.