Dust in AIDA Cloud Chamber Immersion Freezing Experiments

Aerosols are defined as liquid or solid particles suspended in air. Their diverse composition and different sources impede a uniform handling regarding their ice nucleating ability and efficiency. Heterogeneous ice nucleation - triggered by aerosol - is the major mechanism leading to mixed phase clouds and is therefore still one of the topics of interest and research. Model studies (e.g. Hoose et al. (2010)), in-situ measurements (Cziczo et al. (2013)) as well as laboratory studies (Steinke et al. in prep) point out the importance of natural dust for heterogeneous ice nucleation. The variety of used dust species shows the importance of the source and chemical features for forming ice by immersion freezing.

The AIDA (Aerosol Interactions and Dynamics in the Atmosphere) cloud chamber was used for a series of ice nucleation experiments with, among others, different natural dust species to investigate the different ice nucleating behavior. These studies result in a comprehensive overview of the ice nucleation efficiency as a function of aerosol characteristics, temperature and humidity. Two different approaches have been developed and applied to parameterize the experimental data, in order to use these parameterizations to describe ice formation in models. Up to now it appears unclear whether the Classical Nucleation Theory based approach or the so called Ice Nucleation Active Surface Site (INAS-) density approach is more appropriate to formulate ice nucleating activity. Based on studies showing the time independence of AIDA ice nucleation experiments (Steinke et al. (2014)), we use in this study the INAS- density approach to develop a comprehensive parameterization for atmospherically relevant aerosols spanning the full temperature and humidity range

This conference contribution will summarize recent findings from the AIDA cloud chamber for different dust species including desert dust (Niemand et al. (2012)), soil dust (Steinke et al. in prep.), different clay minerals and volcanic ash particles (Steinke et al. (2011)). Additionally, a comparison of the different dust species regarding ice activity and possible reasons for deviations will be presented.

Cziczo, D., Froyd, K., Hoose, C., Jensen, E., Dioa, M., Zondlo, M., Smith, J., Twohy, C. and Murphy, D. (2013) Science, 340, 1320-1324

Hoose, C., Kristjánsson, J., Chen, J.-P. and Hazra, A. (2010) J. Atmos. Sci., 67, 2483-2503

Hoose, C. and Möhler, O. (2012) Atmos. Chem. Phys., 12, 9817-9854

Niemand, M., Möhler, O., Vogel, B., Hoose, C., Connolly, P., Klein, H., Bingemer, H., DeMott, P.J., Skrotzki, J. and Leisner, T. (2012) J. Atmos. Sci., 69, 3077-3092

Steinke, I., Möhler, O., Kiselev, A., Niemand, M., Saathoff, H., Schnaiter, M., Skrotzki, J., Hoose, C. and Leisner, T. (2011) Atmos. Chem. Phys., 11, 12945-12958

Steinke, I., Hoose, C., Möhler, O., Connolly, P. and Leisner, T. (2014) Atmos. Chem. Phys. Discuss., 14, 18499-18539