Interaction of Aerosols with Clouds and Radiation
Final Report Abstract
The scientific foci of this project were to improve our knowledge of (a) the formation of ice particles in cold clouds and (b) the microphysical and light scattering properties of these ice particles. The idea was to investigate these questions on the mountain top site Jungfraujoch (3580 MAMSL), which is in frequent contact with clouds and which is located in the free troposphere most of the time (i.e. with no local influences). For this, a novel inlet was invented and built in order to selectively extract ice particles from mixed-phase clouds that are dominated in number by liquid droplets (at least by a factor of 1000 to 10000). With help of the particle phase discriminator (PPD-2K), which was funded by DFG, the functional concept of the inlet was proven. As the inlet uses a non-intrusive method to select the ice particles, the PPD-2K measurements were the key in this proof of concept and gave quantitative data on the remaining transmission of droplets and the microphysical alterations of the ice particles after passing the inlet. One surprising observation in this context was that the ice particles are prone to structural modifications while passing the ice saturated evaporation section of the inlet. Therefore, the intended studies of the microphysical properties of mixed-phase cloud ice particles with the PPD-2K downstream the ISI wasn’t possible. These studies were performed based on concurrent measurements with a second phase discriminator (SID-3) that directly sampled the cloud. These measurements gave evidence of the frequent existence of a high number concentration of small ice particles (Dp<20 µm) in mixed-phase clouds. Further dedicated research with PPD-2K and SID-3 types of instruments is necessary in order to understand this observation. New and interesting results from the ice residual measurements are that fluorescing (biological) aerosol particles are enriched in the ice residues while refractive black carbon (rBC) particles from combustion processes are depleted. Therefore, a potential anthropogenic climate impact of BC via the glaciation effect in mixed-phase clouds is likely to be negligible.
Publications
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(2014). Laboratory study of microphysical and scattering properties of corona-producing cirrus clouds. Appl. Opt., 53(31), 7566–7575
Järvinen, E., Vochezer, P., Möhler, O., & Schnaiter, M.
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(2014). The Cloud Particle Spectrometer with Polarization Detection (CPSPD): A next generation open-path cloud probe for distinguishing liquid cloud droplets from ice crystals. Atmos. Res. 142, 2–14
Baumgardner, D., Newton, R., Krämer, M., Meyer, J., Beyer, A., Wendisch, M., Vochezer, P.
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(2015). The Ice Selective Inlet: a novel technique for exclusive extraction of pristine ice crystals in mixed-phase clouds, Atmos. Meas. Tech., 8, 3087-3106
Kupiszewski, P., Weingartner, E., Vochezer, P., Schnaiter, M., Bigi, A., Gysel, M., Rosati, B., Toprak, E., Mertes, S., and Baltensperger, U.
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(2015). Transition operator calculation with Green’s dyadic technique for electromagnetic scattering: A numerical approach using the Dyson equation. Journal of Quantitative Spectroscopy and Radiative Transfer, 162, 77–88
Tricoli, U., Vochezer, P., & Pfeilsticker, K.
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(2016). Cloud chamber experiments on the origin of ice crystal complexity in cirrus clouds, Atmospheric Chemistry and Physics, 16(8), 5091–5110
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.
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(2016). Development and characterization of an ice-selecting pumped counterflow virtual impactor (IS-PCVI) to study ice crystal residuals. Atmospheric Measurement Techniques Discussions, 1–41
Hiranuma, N., Möhler, O., Kulkarni, G., Schnaiter, M., Vogt, S., Vochezer, P., Järvinen, E., Wagner, R., Bell, D., Wilson, J., Zelenyuk, A., Cziczo, D. J.
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(2016). Ice residual properties in mixed-phase clouds at the high-alpine Jungfraujoch site. Journal of Geophysical Research: Atmospheres, 121(20), 12,343-12,362
Kupiszewski, P., Zanatta, M., Mertes, S., Vochezer, P., Lloyd, G., Schneider, J., Schenk, L., Schnaiter, M., Baltensperger, U., Weingartner, E., Gysel, M.
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(2016). In situ characterization of mixed phase clouds using the Small Ice Detector and the Particle Phase Discriminator. Atmospheric Measurement Techniques, 9, 159–177
Vochezer, P., Järvinen, E., Wagner, R., Kupiszewski, P., Leisner, T., & Schnaiter, M.
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(2016). Quasi-spherical Ice in Convective Clouds. Journal of the Atmospheric Sciences, JAS-D-15-0365.1
Järvinen, E., Schnaiter, M., Mioche, G., Jourdan, O., Shcherbakov, V. N., Costa, A., Afchine, A., Krämer, M., Heidelberg, F., Jurkat, T., Voigt, C., Schlager, H., Nichman, L., Gallagher, M., Hirst, E., Schmitt, C., Bansemer, A., Heymsfield, A., Lawson, P., Tricoli, U., Pfeilsticker, K., Vochezer, P., Möhler, O., and Leisner, T.
