Journal cover Journal topic
Atmospheric Measurement Techniques An interactive open-access journal of the European Geosciences Union
Journal topic

Journal metrics

Journal metrics

  • IF value: 3.400 IF 3.400
  • IF 5-year value: 3.841 IF 5-year
    3.841
  • CiteScore value: 3.71 CiteScore
    3.71
  • SNIP value: 1.472 SNIP 1.472
  • IPP value: 3.57 IPP 3.57
  • SJR value: 1.770 SJR 1.770
  • Scimago H <br class='hide-on-tablet hide-on-mobile'>index value: 70 Scimago H
    index 70
  • h5-index value: 49 h5-index 49
Discussion papers
https://doi.org/10.5194/amt-2019-352
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/amt-2019-352
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 04 Nov 2019

Submitted as: research article | 04 Nov 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Atmospheric Measurement Techniques (AMT).

Microphysical properties and fall speed measurements of snow ice crystals using the Dual Ice Crystal Imager (D-ICI)

Thomas Kuhn and Sandra Vázquez-Martín Thomas Kuhn and Sandra Vázquez-Martín
  • Luleå University of Technology, Department of Computer Science, Electrical and Space Engineering, Division of Space Technology, 98128 Kiruna, Sweden

Abstract. Accurate predictions of snowfall require good knowledge of the microphysical properties of the snow ice crystals and particles. Shape is an important parameter as it influences strongly the scattering properties of the ice particles, and thus their response to remote sensing techniques such as radar measurements. The fall speed of ice particles is another important parameter for both numerical forecast models as well as representation of ice clouds and snow in climate models, as it is responsible for the rate of removal of ice from these models.

We describe a new ground-based in-situ instrument, the Dual Ice Crystal Imager (D-ICI), to determine snow ice crystal properties and fall speed simultaneously. The instrument takes two high-resolution pictures of the same falling ice particle from two different viewing directions. Both cameras use a microscope-like set-up resulting in an image pixel resolution of approximately 4 μm/pixel. One viewing direction is horizontal and is used to determine fall speed by means of a double exposure. For this purpose, two bright flashes of a light emitting diode behind the camera illuminate the falling ice particle and create this double exposure and the vertical displacement of the particle provides its fall speed. The other viewing direction is close to vertical and is used to provide size and shape information from single-exposure images. This viewing geometry is chosen instead of a horizontal one because shape and size of ice particles as viewed in the vertical direction are more relevant than these properties viewed horizontally as the vertical fall speed is more strongly influenced by the vertically viewed properties. In addition, a comparison with remote sensing instruments that mostly have a vertical or close to vertical viewing geometry is favoured when the particle properties are measured in the same direction.

The instrument has been tested in Kiruna, northern Sweden (67.8° N, 20.4° E). Measurements are demonstrated with images from different snow events, and the determined snow ice crystal properties are presented.

Thomas Kuhn and Sandra Vázquez-Martín
Interactive discussion
Status: open (until 30 Dec 2019)
Status: open (until 30 Dec 2019)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
[Subscribe to comment alert] Printer-friendly Version - Printer-friendly version Supplement - Supplement
Thomas Kuhn and Sandra Vázquez-Martín
Thomas Kuhn and Sandra Vázquez-Martín
Viewed  
Total article views: 108 (including HTML, PDF, and XML)
HTML PDF XML Total BibTeX EndNote
88 18 2 108 0 1
  • HTML: 88
  • PDF: 18
  • XML: 2
  • Total: 108
  • BibTeX: 0
  • EndNote: 1
Views and downloads (calculated since 04 Nov 2019)
Cumulative views and downloads (calculated since 04 Nov 2019)
Viewed (geographical distribution)  
Total article views: 39 (including HTML, PDF, and XML) Thereof 39 with geography defined and 0 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 14 Nov 2019
Publications Copernicus
Download
Short summary
Directly measured shape and fall speed are two important parameters needed for models and remote sensing. This can be done by the new instrument dual ice crystal imager (D-ICI), which takes two high-resolution pictures of falling snow crystals from two different angles. Fall speed is measured by doubly exposing the side-view picture. Size and shape are determined from the second picture providing the top view of the snow crystal. D-ICI has been tested on the ground in Kiruna, northern Sweden.
Directly measured shape and fall speed are two important parameters needed for models and remote...
Citation