Aircraft observations of ice nucleating particles over the Northern China Plain: Two cases studies

While the concentration of ice nucleating particles (INPs) in the cloud layer is more relevant to the cloud processes, most previous measurements of INPs were conducted on the ground. Given the lack of knowledge of vertical distribution characteristics of ice nucleating particles (INPs) over China, airborne measurements focused on the INP vertical profiles were conducted over Northern China Plain on December 27, 2018 and May 12, 2019. The INPs data, sampled from 0.5 to 5.5 km above ground, were analyzed using a static vacuum water vapor diffusion chamber. The observed INP concentration ranges from 0.13 to 10.53 L-1 at nucleation temperature from -17 to -26 degrees C and generally decreases with height. In addition, the large aerosols (> 0.5 mu m) sampled at higher altitudes have a better ice nucleation capacity based on the vertical distribution of activated fractions. The INPs sampled in the low humidity area show a strong correlation (R-2 > 0.7) with aerosol particles larger than 0.5 mu m in diameter, indicating that the number concentration of large aerosols (> 0.5 mu m) is an important parameter in INP concentration parameterization at high altitudes.

Automated summary

Airborne measurements were conducted to study the vertical distribution of ice nucleating particles (INPs) over the Northern China Plain, revealing that aerosols sampled at higher altitudes have better ice nucleation capacity. Additionally, a strong correlation was found between INPs sampled in low humidity areas and aerosol particles larger than 0.5 μm in diameter.