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Lidar observation of spherical particles in a -65°cold cirrus observed above Sodankyla (Finland) during S.E.S.A.M.E.

Del Guasta, Massimo ; Morandi, Marco ; Stefanutti, Leopoldo ; Balestri, Stefano ; Kyro, Esko ; Rummukainen, Markku LU orcid ; Kivi, Rigel ; Rizi, Vincenzo ; Stein, Bernhard and Wedekind, Carsten , et al. (1998) In Journal of Aerosol Science 29(3). p.357-374
Abstract

The absence of LIDAR depolarization in a polar cirrus observed above Sodankyla (Finland) showed the presence of spherical particles at -65°C. The presence of pure liquid water is excluded, since homogeneous freezing should occur at or above -40°C. The cirrus layer was detected at the tropopause, during the horizontal and vertical advection above northern Scandinavia of warm and wet oceanic air. Two alternative explanations are suggested, the first one involving the presence of large, deliquescent tropospheric CN, freezing at very low temperature, and the second one involving the presence of metastable, spherical ice-particles produced in the fast adiabatic cooling of the airmasses. The second hypothesis is less reasonable because the... (More)

The absence of LIDAR depolarization in a polar cirrus observed above Sodankyla (Finland) showed the presence of spherical particles at -65°C. The presence of pure liquid water is excluded, since homogeneous freezing should occur at or above -40°C. The cirrus layer was detected at the tropopause, during the horizontal and vertical advection above northern Scandinavia of warm and wet oceanic air. Two alternative explanations are suggested, the first one involving the presence of large, deliquescent tropospheric CN, freezing at very low temperature, and the second one involving the presence of metastable, spherical ice-particles produced in the fast adiabatic cooling of the airmasses. The second hypothesis is less reasonable because the absence of depolarized LIDAR signal implies a strict cylindrical symmetry in the particles, a symmetry that is difficult to maintain during the freezing process.

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publishing date
type
Contribution to journal
publication status
published
in
Journal of Aerosol Science
volume
29
issue
3
pages
18 pages
publisher
Elsevier
external identifiers
  • scopus:0032030834
ISSN
0021-8502
DOI
10.1016/S0021-8502(97)10008-8
language
English
LU publication?
no
id
5912bab7-1386-4c5f-ada0-c5603ce99bf8
date added to LUP
2025-09-30 18:54:23
date last changed
2025-10-01 11:08:18
@article{5912bab7-1386-4c5f-ada0-c5603ce99bf8,
  abstract     = {{<p>The absence of LIDAR depolarization in a polar cirrus observed above Sodankyla (Finland) showed the presence of spherical particles at -65°C. The presence of pure liquid water is excluded, since homogeneous freezing should occur at or above -40°C. The cirrus layer was detected at the tropopause, during the horizontal and vertical advection above northern Scandinavia of warm and wet oceanic air. Two alternative explanations are suggested, the first one involving the presence of large, deliquescent tropospheric CN, freezing at very low temperature, and the second one involving the presence of metastable, spherical ice-particles produced in the fast adiabatic cooling of the airmasses. The second hypothesis is less reasonable because the absence of depolarized LIDAR signal implies a strict cylindrical symmetry in the particles, a symmetry that is difficult to maintain during the freezing process.</p>}},
  author       = {{Del Guasta, Massimo and Morandi, Marco and Stefanutti, Leopoldo and Balestri, Stefano and Kyro, Esko and Rummukainen, Markku and Kivi, Rigel and Rizi, Vincenzo and Stein, Bernhard and Wedekind, Carsten and Mielke, Bernd and Matthey, Renaud and Mitev, Valentin and Douard, Mathilde}},
  issn         = {{0021-8502}},
  language     = {{eng}},
  month        = {{03}},
  number       = {{3}},
  pages        = {{357--374}},
  publisher    = {{Elsevier}},
  series       = {{Journal of Aerosol Science}},
  title        = {{Lidar observation of spherical particles in a -65°cold cirrus observed above Sodankyla (Finland) during S.E.S.A.M.E.}},
  url          = {{http://dx.doi.org/10.1016/S0021-8502(97)10008-8}},
  doi          = {{10.1016/S0021-8502(97)10008-8}},
  volume       = {{29}},
  year         = {{1998}},
}