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Assessment of techniques for analyzing snow crystals in two dimensions

Assessment of techniques for analyzing snow crystals in two dimensions
Assessment of techniques for analyzing snow crystals in two dimensions
Three-dimensional (3-D) snow analysis techniques provide comprehensive and accurate snow microstructure data. Nevertheless, there remains a requirement for less elaborate methods for snow characterization, as numerical snow models such as SNOWPACK are presently based on two-dimensional (2-D) grain analysis. We present a detailed assessment of various methods and shape descriptors used for snow characterization from digitized images. Dendricity, the ratio of the square of grain perimeter to its area, allows distinction between new and old snow while sphericity distinguishes between faceted and rounded grains. The concept of sphericity is based on curvature, yet another powerful shape descriptor. However, curvatures obtained from images of disaggregated snow grains depend on both resolution and methods chosen. We compared the standard parabola method with a cubic smoothing spline approach for curvature measurement. Applying both methods to parametrically generated shapes, descriptor values were compared with their analytical counterparts. The spline method was found to be able to measure a wider range of curvatures accurately, but both methods suffered from a filtering effect. Although some descriptor errors were as high as 50%, a method for effectively outlining snow grains was found. As well as assessing the classification potential of 2-D analysis on full samples, new descriptors were also investigated.
0260-3055
103-112
Bartlett, S.J.
6e10c1a9-5426-4982-9c51-2f3350c50887
Rüedi, J.-D
c90c6fa3-7cee-42b8-baf6-494f456e489d
Craig, A.
8af74d0c-ec6c-4b53-ab80-e09367cca21d
Fierz, C.
2e2d1604-ae17-4a17-b37f-a8a3d2fd99ec
Bartlett, S.J.
6e10c1a9-5426-4982-9c51-2f3350c50887
Rüedi, J.-D
c90c6fa3-7cee-42b8-baf6-494f456e489d
Craig, A.
8af74d0c-ec6c-4b53-ab80-e09367cca21d
Fierz, C.
2e2d1604-ae17-4a17-b37f-a8a3d2fd99ec

Bartlett, S.J., Rüedi, J.-D, Craig, A. and Fierz, C. (2008) Assessment of techniques for analyzing snow crystals in two dimensions. Annals of Glaciology, 48, 103-112.

Record type: Article

Abstract

Three-dimensional (3-D) snow analysis techniques provide comprehensive and accurate snow microstructure data. Nevertheless, there remains a requirement for less elaborate methods for snow characterization, as numerical snow models such as SNOWPACK are presently based on two-dimensional (2-D) grain analysis. We present a detailed assessment of various methods and shape descriptors used for snow characterization from digitized images. Dendricity, the ratio of the square of grain perimeter to its area, allows distinction between new and old snow while sphericity distinguishes between faceted and rounded grains. The concept of sphericity is based on curvature, yet another powerful shape descriptor. However, curvatures obtained from images of disaggregated snow grains depend on both resolution and methods chosen. We compared the standard parabola method with a cubic smoothing spline approach for curvature measurement. Applying both methods to parametrically generated shapes, descriptor values were compared with their analytical counterparts. The spline method was found to be able to measure a wider range of curvatures accurately, but both methods suffered from a filtering effect. Although some descriptor errors were as high as 50%, a method for effectively outlining snow grains was found. As well as assessing the classification potential of 2-D analysis on full samples, new descriptors were also investigated.

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More information

Published date: 2008
Additional Information: Event Dates: 2-14 July 2007
Venue - Dates: Selected papers from the cryospheric section of the IUGG meeting held in the city of Perugia, Italy,, Perugia, Italy, 2007-07-01 - 2007-07-13
Organisations: Electronics & Computer Science, Agents, Interactions & Complexity

Identifiers

Local EPrints ID: 271559
URI: http://eprints.soton.ac.uk/id/eprint/271559
ISSN: 0260-3055
PURE UUID: 477201ae-08b5-404a-a43f-72cbefb4f14e

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Date deposited: 17 Sep 2010 21:09
Last modified: 07 Jan 2022 21:18

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Contributors

Author: S.J. Bartlett
Author: J.-D Rüedi
Author: A. Craig
Author: C. Fierz

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