The Xiamen Symposium on Marine Environmental Sciences (XMAS 2025)

The sources, chemical compositions, and aging of particles within atmospheric boundary layer are complex. They affect ice nucleation efficiency of particles and thus cloud formation and cloud properties. The vertical characterization of ice nucleation efficiency and physicochemical properties of ice-nucleating particles (INPs) are crucial for a better understanding in their effects on climate. However, they are still poorly understood. Here, we collected particles at different heights over the Bohai Sea using a sampling system based on an unmanned aerial vehicle. Onset conditions for heterogeneous ice nucleation on particles collected under different weather conditions were investigated. Ice nucleation potential of particles shows different vertical variations under different weather conditions, which is likely related to particle surface areas and chemical compositions. Particles during dust period exhibit a higher ice nucleation efficiency. Individual INPs were identified and analyzed by scanning electron microscopy with energy dispersive X-ray analysis to obtain morphology and elemental composition. Dominated INP types are aged sea salt/sulfate particles and organic/sulfate particles during non-dust and sea fog period, whereas dust and fresh sea salt particles have higher contributions during dust period. We find that fresh sea salt particles and aged sea salt/sulfate particles tend to serve as better INPs.