TY  - JOUR
A1  - Nichman, Leonid
A1  - Fuchs, Claudia
A1  - Järvinen, Emma
A1  - Ignatius, Karoliina
A1  - Höppel, Niko Florian
A1  - Dias, Antonio
A1  - Heinritzi, Martin
A1  - Simon, Mario
A1  - Tröstl, Jasmin
A1  - Wagner, Andrea Christine
A1  - Wagner, Robert
A1  - Williamson, Christina
A1  - Yan, Chao
A1  - Bianch, Federico
A1  - Connolly, Paul J.
A1  - Dorsey, James Robert
A1  - Duplissy, Jonathan
A1  - Ehrhart, Sebastian
A1  - Frege, Carla
A1  - Gordon, Hamish
A1  - Hoyle, Christopher Robert
A1  - Kristensen, Thomas Bjerring
A1  - Steiner, Gerhard
A1  - Donahue, Neil McPherson
A1  - Flagan, Richard C.
A1  - Gallagher, Martin William
A1  - Kirkby, Jasper
A1  - Möhler, Ottmar
A1  - Saathoff, Harald
A1  - Schnaiter, Martin
A1  - Stratmann, Frank
A1  - Tomé, Antonio
T1  - Discrimination of water, ice and aerosols by light polarisation in the CLOUD experiment
T2  - Atmospheric chemistry and physics. Discussions
N2  - Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather and General Circulation Models (GCMs). The simultaneous detection of aerosol particles, liquid droplets, and ice crystals, especially in the small cloud-particle size range below 50 µm, remains challenging in mixed phase, often unstable ice-water phase environments. The Cloud Aerosol Spectrometer with Polarisation (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure their effects on the backscatter polarisation state. Here we operate the versatile Cosmics-Leaving- OUtdoor-Droplets (CLOUD) chamber facility at the European Organisation for Nuclear Research (CERN) to produce controlled mixed phase and other clouds by adiabatic expansions in an ultraclean environment, and use the CASPOL to discriminate between different aerosols, water and ice particles. In this paper, optical property measurements of mixed phase clouds and viscous Secondary Organic Aerosol (SOA) are presented. We report observations of significant liquid – viscous SOA particle polarisation transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarisation ratios during phase transition. A classification map is presented for water droplets, organic aerosol (e.g., SOA and oxalic acid), crystalline substances such as ammonium sulphate, and volcanic ash. Finally, we discuss the benefits and limitations of this classi- fication approach for atmospherically relevant concentration and mixtures with respect to the CLOUD 8–9 campaigns and its potential contribution to Tropical Troposphere Layer (TTL) analysis.
Y1  - 2015
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/41888
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-418887
UR  - http://www.atmos-chem-phys-discuss.net/15/31433/2015
SN  - 1680-7375
SN  - 1680-7367
N1  - © Author(s) 2015. CC Attribution 3.0 License.
VL  - 15
SP  - 31433
EP  - 31469
PB  - European Geosciences Union
CY  - Katlenburg-Lindau
ER  -