Assessing the global contribution of marine, terrestrial bioaerosols, and desert dust to ice-nucleating particle concentrations

Aerosol-cloud interactions, and particularly ice crystals in mixed-phase clouds (MPC), stand as a key source of uncertainty in climate change assessments. State-of-the-art laboratory-based parameterizations were introduced into a global chemistry-transport model to investigate the contribution of mineral dust, marine primary organic aerosol (MPOA), and terrestrial primary biological aerosol particles (PBAP) to ice nucleating particles (INP) in MPC. INP originating from PBAP (INP _PBAP) are found to be the primary source of INP at low altitudes between -10 °C and -20 °C, particularly in the tropics, with a pronounced peak in the Northern Hemisphere (NH) during boreal summer. INP _PBAP contributes about 27 % (in the NH) and 30 % (in the SH) of the INP population. Dust-derived INP (INP _D) show a prominent presence at high altitudes in all seasons, dominating at temperatures below -25 °C, constituting 68 % of the INP average column burden. MPOA-derived INP (INP _MPOA) dominate in the Southern Hemisphere (SH), particularly at subpolar and polar latitudes at low altitudes for temperatures below -16 °C, representing approximately 46 % of INP population in the SH. When evaluated against available global observational INP data, the model achieves its highest predictability across all temperature ranges when both INP _D and INP _MPOA are included. The additional introduction of INP _PBAP slightly reduces model skills for temperatures lower than -16 ^oC; however, INP _PBAP are the main contributors to warm-temperature ice nucleation events. Therefore, consideration of dust and marine and terrestrial bioaerosol as IPN precursors is required to simulate ice nucleation in climate models. In this respect, emissions, ice-nucleating activity of each particle type and its evolution during atmospheric transport require further investigations.