The Portable Ice Nucleation Experiment (PINE): A New Instrument for Semiautonomous Measurements of Atmospheric Ice Nucleating Particles

Clouds containing ice play a crucial role in the Earth’s energy balance and water cycle. However, understanding the formation and further development of these clouds remains a challenge. This is partly due to some fundamental knowledge gaps on the first formation of ice crystals, which can occur heterogeneously in the presence of ice nucleating particles (INPs). Despite their importance, the characterization and the quantification of INPs relevant for atmospheric processes is insufficient, and INP measurement techniques are limited.

We present the newly developed ice chamber PINE (Portable Ice Nucleation Experiment), which is an expansion chamber mimicking cloud formation upon air mass lifting. PINE is the first fully automated instrument to measure online INP concentrations with a high sensitivity and time resolution. The chamber can be operated between ~263 K and ~223 K, with a limit of detection of ~0.1 L-1 for a time resolution of an hour. PINE is capable to measure INPs above water saturation (immersion freezing) as well as below water saturation (deposition nucleation). As such it has great potential to not only monitor ambient INP concentrations over long time periods, but also to conduct detailed ice nucleation experiments with specific aerosol particles.

We present results from characterization experiments at the AIDA (Aerosol Interaction and Dynamics in the Atmosphere) cloud chamber, to determine the instrument’s measurement range. Furthermore, PINE was operated in several field campaigns in Hyytiälä (Finnland), on Puy de Dôme (France), and in Karlsruhe (Germany). Each of the campaigns lasted for several weeks to months, during which PINE continuously measured INP concentrations. These measurements proved the chamber to operate well and autonomously for a long time period, making it suitable for intensive ambient measurement, as well as for laboratory applications.