The Concentrations of Atmospheric Ice Nuclei and Their Relation with Aerosol Particles in Different Regions in China

Since 2011, the concentration of ice nuclei (IN) and the aerosol particles were simultaneously measured at Nanjing (a megacity in east China), Mts. Huangshan (a relatively clean mountainous site in east China), and Kuche (a desert region in Xinjiang, northwest China). The variations of IN concentration with temperature, supersaturation and concentrations of aerosol particles of different sizes were analyzed. It was found that the concentrations of IN are the highest in the spring, followed by autumn, and the lowest is in the summer. This is possibly due to a greater abundance of soil dust particles in spring and autumn, while in summer more frequent rainfall could wash out a large number of IN.

A comparison of the concentrations of IN at three different altitudes showed (refer the supplementary file for more detailed information) that the concentration of IN at the foot of the mountains was higher than that at the summit, indicating that more aerosols near the ground cause high concentrations of IN. Further analysis of the source of atmospheric ice nuclei found that high correlation between IN and aerosol particles with size larger than 0.5μm, indicating that the large aerosol particles contribute more to IN. Through the comparison with the IN measurements obtained in three different regions, it is found that the number concentration of IN in Nanjing is the highest, followed by that in Xinjiang (no–dust days), and the lowest on Mts. Huangshan. As for the proportionality of IN number concentration to aerosol particle concentration, it is the highest in Xinjiang and the lowest on Mts. Huangshan.

In addition, parameterizations were developed based on measurements to represent the variations of IN concentration with temperature, supersaturation, and the number concentration of aerosol particles with size larger than 0.5μm. They can be applied to the surface of the desert, the relatively clean background areas and the polluted city regions.