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| Titel |
3-D image-based numerical computations of snow permeability: links to specific surface area, density, and microstructural anisotropy |
| VerfasserIn |
N. Calonne, C. Geindreau, F. Flin, S. Morin, B. Lesaffre, S. Rolland du Roscoat, P. Charrier |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1994-0416
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| Digitales Dokument |
URL |
| Erschienen |
In: The Cryosphere ; 6, no. 5 ; Nr. 6, no. 5 (2012-09-10), S.939-951 |
| Datensatznummer |
250003779
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| Publikation (Nr.) |
 copernicus.org/tc-6-939-2012.pdf |
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| Zusammenfassung |
| We used three-dimensional (3-D) images of snow microstructure to carry out
numerical estimations of the full tensor of the intrinsic permeability of
snow (K). This study was performed on 35 snow samples, spanning a
wide range of seasonal snow types.
For several snow samples, a significant anisotropy of permeability was detected
and is consistent with that observed for the effective thermal conductivity obtained
from the same samples. The anisotropy coefficient, defined as the ratio of the
vertical over the horizontal components of K, ranges from 0.74 for
a sample of decomposing precipitation particles collected in the field to 1.66 for a depth hoar specimen.
Because the permeability is related to a characteristic length, we introduced
a dimensionless tensor K*=K/res2, where the
equivalent sphere radius of ice grains (res) is computed from the
specific surface area of snow (SSA) and the ice density (ρi) as
follows: res=3/(SSA×ρi.
We define K and K* as the average of the diagonal components of
K and K*, respectively.
The 35 values of K* were fitted to snow density (ρs) and provide the following
regression: K = (3.0 ± 0.3) res2 exp((−0.0130 ± 0.0003)ρs).
We noted that the anisotropy of permeability does not affect significantly
the proposed equation. This regression curve was applied to several independent
datasets from the literature and compared to other existing regression curves or
analytical models. The results show that it is probably the best currently
available simple relationship linking the average value of permeability, K,
to snow density and specific surface area. |
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