Contributions of Dust Source Regions to Ice Nucleating Particles in Mixed-Phase Clouds Simulated with a Global Climate–Aerosol Model

Abstract Mineral dust is emitted from various arid regions of the world and plays an important role as ice nucleating particles (INPs) in aerosol–cloud interactions and their climate impacts. However, the estimation of the global distribution of dust INPs in mixed-phase clouds is highly uncertain, and their global source contributions have not been evaluated. Here, using a global climate–aerosol model that incorporates ice nucleation parameterizations of dust, we show that the spatial distribution and source contributions of dust INPs differ substantially from those of dust mass both globally and regionally because INP-to-mass ratios vary by an order of magnitude among source regions. For about 60% of Earth’s surface, the dominant source regions (source regions with the largest contribution) of dust mass and INPs are different, or even if the dominant source regions are the same, their contributions to total dust mass and INPs differ by more than 10%. In the midlatitude source regions of the Northern Hemisphere, the contribution of local dust (emitted within a target source region) to total dust INPs is small (21%–56%), suggesting the influence of nonlocal dust on the distributions and amounts of mixed-phase clouds and precipitation and the resulting local dust emission processes. Considering the different rates of increase in dust emissions from preindustrial times to the present among source regions, our results highlight the importance of accurately estimating the emission and transport of dust from each source region for a better understanding of aerosol–cloud interactions through dust ice nucleation and their long-term changes.