Concentration and variability of deposition-mode ice nucleating particles from Mt. Tai of China in the early summer

Abstract

The concentration and chemical composition of aerosol particles were measured and sampled at two altitudes of Mt. Tai, North China Plain in May and June 2017. Concentrations of ice nucleating particles (INP) were analyzed with a static vacuum water vapor diffusion chamber (FRIDGE-NUIST) in deposition mode after being sampled using an electrostatic aerosol collector. The average INP concentration (1.19 to 3.45 L−1) at Mt. Tai matches with the same measured at Tai’ An (foot of the Mt. Tai, 1.57–3.49 L−1, at RHw = 95%, 97%, 99% and t = −20 °C). Correlations between concentrations of aerosol particles and INP were below 0.5 and less than simultaneous measurements made at Tai'An. Clear diurnal variations at the height of the planetary boundary layer (PBL) resulted in changes in aerosol and INP concentrations at the top of the mountain. We found that EC-Aged (aged elemental carbon) and mineral type particles are clearly associated with ice nuclei when the height of the PBL exceeds the altitude of the mountaintop. Furthermore, we found significant correlations between INP concentrations and concentrations of OC (organic carbon) and NaK (sodium/potassium salt) type aerosol particles at night (in the free troposphere). Ice nucleation active surface site densities are higher at night (22:00 LST, local standard time) than during the day (11:00 LST) due to the change in aerosol characteristics. This study shows that OC and NaK type particles may serve as sources of efficient ice nuclei at night.