Long-range transported dust enhances ice nucleating particles abundance and cloud formation in the North China Plain

Ice-nucleating particles (INPs) are critical in cloud formation and precipitation, particularly in continental regions where dust aerosols are prevalent. However, the long-term contributions of transported dust and other sources to INPs remain poorly understood. In this study, we analyzed precipitation samples collected at the summit of Mount Tai (1534 m a.s.l.), a background site in the North China Plain (NCP), from February 24 to November 29 in 2021. The cumulative INP number concentrations per volume of air (NINP_air) ranged from 0.4 × 10-2 to 1.8 L−1, aligning with INP spectra from precipitation and cloud water samples under diverse global conditions. During the observation period, NINP_air were highest in spring, approximately 2.3±1.4 times higher than those in other seasons. The seasonal enhancement was primarily attributed to the longrange transport of dust aerosols, supported by the frequent occurrence of dust events and the highest Dust Aerosol Optical Depth (DAOD) during spring. Additionally, interactions between biological materials and mineral dust appeared to enhance the ice- nucleating activity, triggering freezing at relatively higher temperatures and further increasing INP concentrations during spring. Using a Positive Matrix Factorization (PMF) model, we identified mineral dust contributed 43.6 % of the annual average NINP_air, and the contribution increasing markedly to 71.7 % in spring. Satellite observations further revealed that the long-range transport of dust in spring promotes large-scale cloud formation by forming ice crystals over the NCP. These findings highlight the vital role of transported dust in modulating INP abundance and provide new insights into aerosol-cloud interactions over the continental regions.