Variables & Measurement Techniques

The key-mission of CIS is to offer operational support to ACTRIS National Facilities (NFs) operating instrumentation for continuous long-term measurements of cloud occurrence, cloud water content, and cloud droplet effective diameter at observational platforms, or for episodic measurements of cloud particle size distributions, chemical cloud water composition, and ice nucleating particles during dedicated laboratory and field campaigns.

Observational Platforms

Observational platforms have to provide the two mandatory variables

  • liquid water content
  • droplet effective diameter

and must provide at least two of the specializing variables

  • droplet number concentration
  • droplet size distribution
  • ice particle number concentration
  • ice particle size distribution
  • INP number concentration
  • INP temperature spectrum
  • bulk cloud water chemical composition


Measurement Techniques


mandatory variables

Particulate Volume Monitor PVM-100 from Gerber Scientic Inc.

Fog Monitor GFAS-DPOL from DMT


INP measurements

Continuous Flow Diffusion Chamber HINC (Horizontal Ice Nucleation Chamber)-Auto developed by ETH Zurich

See also technical paper

mobile cloud chamber PINE developed by KIT

See also technical paper and availability at Bilfinger Noell GmbH.



cloud water chemistry

The cloud water chemistry analysis contains both the cloud water sampling with specialized collectors and the subsequent offline chemical analysis by i.e. ion chromatography systems.

cloud particle measurements

Supported instruments for cloud particle measurements are based on Mie-Scattering Probes as CDP and Imaging Probes as CPI.

Exploratory Platforms



09 November 2021, by CCIce

start of first long-term test campaigns with the mobile cloud chamber PINE at the Sonnblick Observatory, Austria and Mt. Helmos Observatory, Greece

Since summer 2021, two PINE instruments from KIT are installed at the potential ACTRIS CIS sites Sonnblick Observatory, Austria and Mt. Helmos Observatory, Greece to perform longterm INP measurements in boundary and free-troposphere conditions. These test campaigns will also show the scientific potential to measure INPs at different location at the same time.