Monitoring of Ice-Nucleating Particle Concentration Using the Portable Ice Nucleation Experiment PINE (Invited Presentation)

The impact of the formation and fate of ice crystals in clouds continues to remain a major uncertainty in the understanding of cloud properties and precipitation formation, partly due to missing knowledge about the abundance and distribution of ice-nucleating particles (INPs) in the troposphere. Ambient INPs can be derived from many sources and possess complex properties. Concerning the fast-changing climate (and thereby sources), it is challenging to keep track of INP abundance without monitoring it with reasonable spatial and time resolutions. Since the 1950s, field campaigns have been performed to measure INPs in different environments, but the majority of INP measurement campaigns have been short-term and many have had a poor time resolution. This limits our ability to understand both temporal and spatial variability in INP, which in turn limits our ability to understand and model sources, transport, and sinks of INP in the atmosphere. We need long-term, high-time resolution measurements to address this, which is now becoming possible with the development of automated instruments that have the potential to form the basis of a global monitoring network. .

Here we present the results of INP concentration measurements from the ice nucleation chamber PINE (Portable Ice Nucleation Experiment), a mobile expansion chamber based on the design of the AIDA (Aerosol Interaction and Dynamics in the Atmosphere). PINE is a fully automated instrument that enables ambient INP concentration measurements even at remote locations with a time resolution of ~ 6 minutes. Data processing is performed with an automated software tool, performing quality checks and controls.

INP concentrations between ~ -20 °C to -30 °C relevant for mixed-phase cloud formation from different field campaigns lasting several months are presented (Fig. 1), demonstrating PINE’s ability as a monitoring instrument. The results are discussed with regard to the different environments (forest, rural background, free troposphere, Arctic and sub-Arctic, dust- and ocean-impacted regions) and seasons.

These activities are within the scope of the establishment of INP monitoring networks, as, e.g., the ACTRIS (Aerosol, Clouds and Trace Gases Research Infrastructure) topical center CIS (Cloud In Situ). There, different mountaintop stations at different altitudes, and in the sub-Arctic and Arctic region will monitor INP concentrations at mixed-phase cloud conditions. This targets to create a unique database to be used by different communities and has the potential to be implemented in models to better represent ice formation in clouds, and thus reduce uncertainties in aerosol-cloud interactions.