Measurement of the ice-nucleating particle concentration with the Portable Ice Nucleation Experiment during the Pallas Cloud Experiment 2022

Abstract. The Portable Ice Nucleation Experiment (PINE) was deployed during the Pallas Cloud Experiment (PaCE) 2022 for a three-month-period at the Sammaltunturi station in autumn 2022. The station is located on top of a hill on the edge between sub-Arctic and boreal forest environments, typically receiving air masses from the Arctic and the south. Since clouds are frequently present at the station during autumn, the present aerosol particles can have a direct impact on cloud properties. Ice-nucleating particles (INPs) are aerosol particles that facilitate primary ice nucleation in supercooled cloud droplets. The PINE measured the INP concentration with a high temporal resolution of six minutes at different nucleation temperatures between 240 K and 252 K. The INP concentration varied exponentially with the freezing temperature and differences between different months were observed. The highest median INP concentration was measured during December over the whole temperature range, while during November the lowest median INP concentration was measured. The data presented here is useful to study aerosol-cloud interactions for a sub-Arctic location with minimal anthropogenic influence. The high temporal resolution allows to correlate the INP concentration with other measurements, such as size distribution data and meteorological data. In addition, the data provides the ice nucleating ability of arriving aerosol particles, which can be combined with models to study the nature, the source and the age of the INPs.