Validating modeled critical crack length for crack propagation in the snow cover model SNOWPACK
Item
Title (Dublin Core)
Validating modeled critical crack length for crack propagation in the snow cover model SNOWPACK
Description (Dublin Core)
<p>Observed snow stratigraphy and snow stability are of key importance for avalanche forecasting. Such observations are rare and snow cover models can improve the spatial and temporal resolution. To evaluate snow stability, failure initiation and crack propagation have to be considered. Recently, a new stability criterion relating to crack propagation, namely the critical crack length, was implemented into the snow cover model SNOWPACK. The critical crack length can also be measured in the field with a propagation saw test, which allows for an unambiguous comparison.
To validate and improve the parameterization for the critical crack length, we used data from 3 years of field experiments performed close to two automatic weather stations above Davos, Switzerland. We monitored seven distinct weak layers and performed in total 157 propagation saw tests on a weekly basis. Comparing modeled to measured critical crack length showed some discrepancies stemming from model assumption. Hence, we replaced two variables of the original parameterization, namely the weak layer shear modulus and thickness, with a fit factor depending on weak layer density and grain size. With these adjustments, the normalized root-mean-square error between modeled and observed critical crack lengths decreased from 1.80 to 0.28.
As the improved parameterization accounts for grain size, values of critical crack lengths for snow layers consisting of small grains, which in general are not weak layers, become larger. In turn, critical weak layers appear more prominently in the vertical profile of critical crack length simulated with SNOWPACK. Hence, minimal values in modeled critical crack length better match observed weak layers. The improved parameterization of critical crack length may be useful for both weak layer detection in simulated snow stratigraphy and also providing more realistic snow stability information – and hence may improve avalanche forecasting.</p>
To validate and improve the parameterization for the critical crack length, we used data from 3 years of field experiments performed close to two automatic weather stations above Davos, Switzerland. We monitored seven distinct weak layers and performed in total 157 propagation saw tests on a weekly basis. Comparing modeled to measured critical crack length showed some discrepancies stemming from model assumption. Hence, we replaced two variables of the original parameterization, namely the weak layer shear modulus and thickness, with a fit factor depending on weak layer density and grain size. With these adjustments, the normalized root-mean-square error between modeled and observed critical crack lengths decreased from 1.80 to 0.28.
As the improved parameterization accounts for grain size, values of critical crack lengths for snow layers consisting of small grains, which in general are not weak layers, become larger. In turn, critical weak layers appear more prominently in the vertical profile of critical crack length simulated with SNOWPACK. Hence, minimal values in modeled critical crack length better match observed weak layers. The improved parameterization of critical crack length may be useful for both weak layer detection in simulated snow stratigraphy and also providing more realistic snow stability information – and hence may improve avalanche forecasting.</p>
Creator (Dublin Core)
B. Richter
J. Schweizer
M. W. Rotach
A. van Herwijnen
Subject (Dublin Core)
Environmental sciences
GE1-350
Geology
QE1-996.5
Publisher (Dublin Core)
Copernicus Publications
Date (Dublin Core)
2019-12-01T00:00:00Z
Type (Dublin Core)
article
Identifier (Dublin Core)
10.5194/tc-13-3353-2019
1994-0416
1994-0424
https://doaj.org/article/f33d9c17a86b4c088f61f6db4d30b447
Source (Dublin Core)
The Cryosphere, Vol 13, Pp 3353-3366 (2019)
Language (Dublin Core)
EN
Relation (Dublin Core)
https://www.the-cryosphere.net/13/3353/2019/tc-13-3353-2019.pdf
https://doaj.org/toc/1994-0416
https://doaj.org/toc/1994-0424
Provenance (Dublin Core)
Journal Licence: CC BY