Diverse Sources and Aging Change the Mixing State and Ice Nucleation Properties of Aerosol Particles Over the Western Pacific and Southern Ocean

Atmospheric particles can impact cloud formation and their microphysics. However, their ability to act as ice-nucleating particles (INPs) over the marine atmosphere are poorly understood. In this study, we found that particles collected over the western Pacific and the Southern Ocean exhibit diverse ice nucleation abilities and mixing states. Multiphase processes on sea salt particles resulted in chlorine deficiency. This selective aging process made the marine particle population more externally mixed. The fresh sea salt particles with organic coatings exhibited the highest depositional ice nucleation ability. The sea salt mixed sulfate particle was enriched in INPs by a factor of 1.9. Further analysis shows that assuming an internally mixed particle population in the marine atmosphere may lead to errors of several orders of magnitude in predicting ice nucleation rates.

Reference: Xue, J., Zhang, T., Park, K., et al. (2024). Diverse sources and aging change the mixing state and ice nucleation properties of aerosol particles over the western Pacific and Southern Ocean. Atmos. Chem. Phys., 24, 7731–7754. https://doi.org/10.5194/acp-24-7731-2024