Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 16, 5091-5110, 2016
© Author(s) 2016. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
25 Apr 2016
Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds
Martin Schnaiter1, Emma Järvinen1, Paul Vochezer1, Ahmed Abdelmonem1, Robert Wagner1, Olivier Jourdan2, Guillaume Mioche2, Valery N. Shcherbakov2, Carl G. Schmitt3, Ugo Tricoli4, Zbigniew Ulanowski5, and Andrew J. Heymsfield3 1Institute of Meteorology and Climate Research – Atmospheric Aerosol Research, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
2Laboratoire de Métérologie et Physique (LaMP), Clermont-Ferrand, France
3National Center for Atmospheric Research (NCAR), Boulder, Colorado, USA
4Institute of Environmental Physics, University of Heidelberg, Heidelberg, Germany
5Centre for Atmospheric and Instrumentation Research, University of Hertfordshire, Hatfield, UK
Abstract. This study reports on the origin of small-scale ice crystal complexity and its influence on the angular light scattering properties of cirrus clouds. Cloud simulation experiments were conducted at the AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber of the Karlsruhe Institute of Technology (KIT). A new experimental procedure was applied to grow and sublimate ice particles at defined super- and subsaturated ice conditions and for temperatures in the −40 to −60 °C range. The experiments were performed for ice clouds generated via homogeneous and heterogeneous initial nucleation. Small-scale ice crystal complexity was deduced from measurements of spatially resolved single particle light scattering patterns by the latest version of the Small Ice Detector (SID-3). It was found that a high crystal complexity dominates the microphysics of the simulated clouds and the degree of this complexity is dependent on the available water vapor during the crystal growth. Indications were found that the small-scale crystal complexity is influenced by unfrozen H2SO4 / H2O residuals in the case of homogeneous initial ice nucleation. Angular light scattering functions of the simulated ice clouds were measured by the two currently available airborne polar nephelometers: the polar nephelometer (PN) probe of Laboratoire de Métérologie et Physique (LaMP) and the Particle Habit Imaging and Polar Scattering (PHIPS-HALO) probe of KIT. The measured scattering functions are featureless and flat in the side and backward scattering directions. It was found that these functions have a rather low sensitivity to the small-scale crystal complexity for ice clouds that were grown under typical atmospheric conditions. These results have implications for the microphysical properties of cirrus clouds and for the radiative transfer through these clouds.

Citation: Schnaiter, M., Järvinen, E., Vochezer, P., Abdelmonem, A., Wagner, R., Jourdan, O., Mioche, G., Shcherbakov, V. N., Schmitt, C. G., Tricoli, U., Ulanowski, Z., and Heymsfield, A. J.: Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds, Atmos. Chem. Phys., 16, 5091-5110,, 2016.
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