Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Phase transition observations and discrimination of small cloud particles by light polarization in expansion chamber experiments

Nichman, Leonid ; Fuchs, Claudia ; Järvinen, Emma ; Ignatius, Karoliina ; Florian Höppel, Niko ; Dias, Antonio ; Heinritzi, Martin ; Simon, Mario ; Tröstl, Jasmin and Christine Wagner, Andrea , et al. (2016) In Atmospheric Chemistry and Physics 16(5). p.3651-3664
Abstract

Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather, and general circulation models. The 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 environments. The Cloud Aerosol Spectrometer with Polarization (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure the variability in polarization state of their backscattered light. Here we operate the versatile Cosmics Leaving OUtdoor Droplets (CLOUD) chamber facility at the European Organization for Nuclear Research (CERN) to... (More)

Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather, and general circulation models. The 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 environments. The Cloud Aerosol Spectrometer with Polarization (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure the variability in polarization state of their backscattered light. Here we operate the versatile Cosmics Leaving OUtdoor Droplets (CLOUD) chamber facility at the European Organization 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 polarization transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarization 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 sulfate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentrations and mixtures with respect to the CLOUD 8-9 campaigns and its potential contribution to tropical troposphere layer analysis.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; ; ; ; ; and , et al. (More)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ; and (Less)
publishing date
type
Contribution to journal
publication status
published
in
Atmospheric Chemistry and Physics
volume
16
issue
5
pages
14 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:84962497840
ISSN
1680-7316
DOI
10.5194/acp-16-3651-2016
language
English
LU publication?
no
id
d0fa9e7e-4fbd-4cee-80a0-c0cd12862881
date added to LUP
2018-10-09 14:33:32
date last changed
2022-02-15 05:18:29
@article{d0fa9e7e-4fbd-4cee-80a0-c0cd12862881,
  abstract     = {{<p>Cloud microphysical processes involving the ice phase in tropospheric clouds are among the major uncertainties in cloud formation, weather, and general circulation models. The 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 environments. The Cloud Aerosol Spectrometer with Polarization (CASPOL) is an airborne instrument that has the ability to detect such small cloud particles and measure the variability in polarization state of their backscattered light. Here we operate the versatile Cosmics Leaving OUtdoor Droplets (CLOUD) chamber facility at the European Organization 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&amp;ndash;viscous SOA particle polarization transitions under dry conditions using CASPOL. Cluster analysis techniques were subsequently used to classify different types of particles according to their polarization 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 sulfate, and volcanic ash. Finally, we discuss the benefits and limitations of this classification approach for atmospherically relevant concentrations and mixtures with respect to the CLOUD 8-9 campaigns and its potential contribution to tropical troposphere layer analysis.</p>}},
  author       = {{Nichman, Leonid and Fuchs, Claudia and Järvinen, Emma and Ignatius, Karoliina and Florian Höppel, Niko and Dias, Antonio and Heinritzi, Martin and Simon, Mario and Tröstl, Jasmin and Christine Wagner, Andrea and Wagner, Robert and Williamson, Christina and Yan, Chao and James Connolly, Paul and Robert Dorsey, James and Duplissy, Jonathan and Ehrhart, Sebastian and Frege, Carla and Gordon, Hamish and Robert Hoyle, Christopher and Bjerring Kristensen, Thomas and Steiner, Gerhard and McPherson Donahue, Neil and Flagan, Richard and William Gallagher, Martin and Kirkby, Jasper and Möhler, Ottmar and Saathoff, Harald and Schnaiter, Martin and Stratmann, Frank and Tomé, António}},
  issn         = {{1680-7316}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{5}},
  pages        = {{3651--3664}},
  publisher    = {{Copernicus GmbH}},
  series       = {{Atmospheric Chemistry and Physics}},
  title        = {{Phase transition observations and discrimination of small cloud particles by light polarization in expansion chamber experiments}},
  url          = {{http://dx.doi.org/10.5194/acp-16-3651-2016}},
  doi          = {{10.5194/acp-16-3651-2016}},
  volume       = {{16}},
  year         = {{2016}},
}