The characteristics of atmospheric ice nuclei measured at different altitudes in the Huangshan Mountains in Southeast China

Abstract

The concentration of ice nuclei (IN) and the relationship with aerosol particles were measured and analyzed using three 5-L mixing cloud chambers and a static diffusion cloud chamber at three altitudes in the Huangshan Mountains in Southeast China from May to September 2011. The results showed that the mean total number concentration of IN on the highest peak of the Huangshan Mountains at an activation temperature (T a) of −20°C was 16.6 L−1. When the supersaturation with respect to water (S w) and with respect to ice (S i) were set to 5%, the average number concentrations of IN measured at an activation temperature of −20°C by the static diffusion cloud chamber were 0.89 and 0.105 L−1, respectively. A comparison of the concentrations of IN at three different altitudes showed that the concentration of IN at the foot of the mountains was higher than at the peak. A further calculation of the correlation between IN and the concentrations of aerosol particles of different size ranges showed that the IN concentration was well correlated with the concentration of aerosol particles in the size range of 1.2–20 μm. It was also found that the IN concentration varied with meteorological conditions, such as wind speed, with higher IN concentrations often observed on days with strong wind. An analysis of the backward trajectories of air masses showed that low IN concentrations were often related to air masses travelling along southwest pathways, while higher IN concentrations were usually related to those transported along northeast pathways.