A new instrument for measuring ice-nucleating particles in the free troposphere and at temperatures relevant for cirrus formation: development and first applications

A minor and strongly temperature-dependent fraction of atmospheric aerosols, called Ice Nucleating Particles (INPs), is known to impact the weather and climate systems by inducing the formation of ice in mixed-phase and cirrus clouds. There is increasing evidence that INPs not only induce the formation of precipitation in particular over continental areas, but also have an important impact on the radiative properties of a number of cloud types throughout the troposphere. For cirrus formation, the abundance and types of INPs play important roles in the interplay between heterogeneous and homogeneous ice nucleation pathways, leading to either net cooling or heating of cirrus clouds in the global climate system.

During the previous years, the new instrument PINEair was developed for measuring INPs at cirrus formation temperatures between -40°C and -65°C and ice supersaturations of up to about 100%. The new instrument can be operated both onboard research aircrafts or at high altitude mountain stations. It is based on the PINE (Portable Ice Nucleation Experiment) instrument, which was developed for laboratory experiments on ice nucleation processes and for automated operation during longer-term INP monitoring activities in the field. PINEair is developed and optimized for direct sampling in the free troposphere.

This contribution will explain the working principle of the new instrument, describe the development and setup of the prototype version, discuss the results of first INP measurements both in the laboratory and at a high-altitude mountain station, and outlines the next steps for building the final aircraft-based version of PINEair.