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

Abstract

Abstract 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\xa0km above ground, were analyzed using a static vacuum water vapor diffusion chamber. The observed INP concentration ranges from 0.13 to 10.53\xa0L−1 at nucleation temperature from −17 to −26\xa0°C and generally decreases with height. In addition, the large aerosols (>0.5\xa0μm) 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 (R2\xa0>\xa00.7) with aerosol particles larger than 0.5\xa0μm in diameter, indicating that the number concentration of large aerosols (>0.5\xa0μm) is an important parameter in INP concentration parameterization at high altitudes.