2017, Coluzza, Ivan, Creamean, Jessie, Rossi, Michel J., Wex, Heike, Alpert, Peter Aaron, Bianco, Valentino, Boose, Yvonne, Dellago, Christoph, Felgitsch, Laura, Fröhlich-Nowoisky, Janine, Herrmann, Hartmut, Jungblut, Swetlana, Kanji, Zamin A., Menzl, Georg, Moffett, Bruce, Moritz, Clemens, Mutzel, Anke, Pöschl, Ulrich, Schauperl, Michael, Scheel, Jan, Stopelli, Emiliano, Stratmann, Frank, Grothe, Hinrich, Schmale, David G.

There has been increasing interest in ice nucleation research in the last decade. To identify important gaps in our knowledge of ice nucleation processes and their impacts, two international workshops on ice nucleation were held in Vienna, Austria in 2015 and 2016. Experts from these workshops identified the following research needs: (1) uncovering the molecular identity of active sites for ice nucleation; (2) the importance of modeling for the understanding of heterogeneous ice nucleation; (3) identifying and quantifying contributions of biological ice nuclei from natural and managed environments; (4) examining the role of aging in ice nuclei; (5) conducting targeted sampling campaigns in clouds; and (6) designing lab and field experiments to increase our understanding of the role of ice-nucleating particles in the atmosphere. Interdisciplinary teams of scientists should work together to establish and maintain a common, unified language for ice nucleation research. A number of commercial applications benefit from ice nucleation research, including the production of artificial snow, the freezing and preservation of water-containing food products, and the potential modulation of weather. Additional work is needed to increase our understanding of ice nucleation processes and potential impacts on precipitation, water availability, climate change, crop health, and feedback cycles.

2021, Villanueva, Diego, Senf, Fabian, Tegen, Ina

Aerosol-cloud interactions are an important source of uncertainty in current climate models. To understand and quantify the influence of ice-nucleating particles in cloud glaciation, it is crucial to have a reliable estimation of the hemispheric and seasonal contrast in cloud top phase, which is believed to result from the higher dust aerosol loading in boreal spring. For this reason, we locate and quantify these contrasts by combining three different A-Train cloud-phase products for the period 2007–2010. These products rely on a spaceborne lidar, a lidar-radar synergy, and a radiometer-polarimeter synergy. We show that the cloud-phase from the product combination is more reliable and that the estimation of the hemispheric and seasonal contrast has a lower error compared to the individual products. To quantify the contrast in cloud-phase, we use the hemispheric difference in ice cloud frequency normalized by the liquid cloud frequency in the southern hemisphere between −42 °C and 0 °C. In the midlatitudes, from −15 to −30 °C, the hemispheric contrasts increase with decreasing temperature. At −30 °C, the hemispheric contrast varies from 29% to 39% for the individual cloud-phase products and from 52% to 73% for the product combination. Similarly, in the northern hemisphere, we assess the seasonal contrast between spring and fall normalized by the liquid cloud frequency during fall. At −30 °C, the seasonal contrast ranges from 21% to 39% for the individual cloud-phase products and from 54% to 75% for the product combination.

2011, Glitsch, Sven, Röpcke, Jürgen, Weichbrodt, Frank

[no abstract available]