Berlin 2014 – scientific programme

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UP: Fachverband Umweltphysik

UP 12: Atmosphäre - Labor

UP 12.6: Talk

Thursday, March 20, 2014, 11:45–12:00, MAG 100

Characterization of ice crystals in the AIDA cloud chamber — •Paul Vochezer, Ahmed Abdelmonem, and Martin Schnaiter — KIT IMK-AAF, Karlsruhe, Germany

Clouds remain a major source of uncertainty for both weather forecasts and climate models. These uncertainties are strongly linked to the occurrence and development of ice particles in clouds. Our group is currently involved in field and laboratory measurements to quantify and qualify ice particles in clouds.

In our contribution we present measurements obtained by two cloud particle probes during a series of laboratory based AIDA cloud chamber experiments with ice containing clouds in a temperature range from -20^∘C to -60^∘C. The PHIPS-HALO instrument includes a stereo microscope which takes real images of individual cloud particles at a resolution of 3µm/pixel. The PPD2-K instrument acquires high resolution 2D scattering patterns of individual cloud particles in forward direction 5^∘-25^∘. Asphericity of the particles leads to deviations from the Airy pattern and allows the discrimination between droplets and ice particles. Symmetric ice particles like columns or plates generate symmetric scattering pattern which are filtered and analyzed habit by habit.

The data sets of PHIPS-HALO and PPD2-K are analyzed to determine the fraction of cloud ice particles and the occurrence of certain ice particle habits. Furthermore the transverse and longitudinal growth rates of airborne columnar ice particles are derived.