Cold-to-warm flow regime transition in snow avalanches.
Large avalanches usually encounter different snow conditions along their track. When they release as slab avalanches comprising cold snow, they can subsequently develop into powder snow avalanches entraining snow as they move down the mountain. Typically, this entrained snow will be cold (T¯¯¯<−1...
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ftunivdurham:oai:dro.dur.ac.uk.OAI2:27002 2023-05-15T18:32:27+02:00 Cold-to-warm flow regime transition in snow avalanches. Köhler, Anselm Fischer, Jan-Thomas Scandroglio, Riccardo Bavay, Mathias McElwaine, Jim Sovilla, Betty 2018-11-30 application/pdf http://dro.dur.ac.uk/27002/ http://dro.dur.ac.uk/27002/1/27002.pdf https://doi.org/10.5194/tc-12-3759-2018 unknown Copernicus Publications dro:27002 issn:1994-0416 issn: 1994-0424 doi:10.5194/tc-12-3759-2018 http://dro.dur.ac.uk/27002/ https://doi.org/10.5194/tc-12-3759-2018 http://dro.dur.ac.uk/27002/1/27002.pdf © Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. CC-BY The cryosphere, 2018, Vol.12(12), pp.3759-3774 [Peer Reviewed Journal] Article PeerReviewed 2018 ftunivdurham https://doi.org/10.5194/tc-12-3759-2018 2020-06-04T22:25:13Z Large avalanches usually encounter different snow conditions along their track. When they release as slab avalanches comprising cold snow, they can subsequently develop into powder snow avalanches entraining snow as they move down the mountain. Typically, this entrained snow will be cold (T¯¯¯<−1 ∘C) at high elevations near the surface, but warm (T¯¯¯>−1 ∘C) at lower elevations or deeper in the snowpack. The intake of warm snow is believed to be of major importance to increase the temperature of the snow composition in the avalanche and eventually cause a flow regime transition. Measurements of flow regime transitions are performed at the Vallée de la Sionne avalanche test site in Switzerland using two different radar systems. The data are then combined with snow temperatures calculated with the snow cover model SNOWPACK. We define transitions as complete when the deposit at runout is characterized only by warm snow or as partial if there is a warm flow regime, but the farthest deposit is characterized by cold snow. We introduce a transition index Ft, based on the runout of cold and warm flow regimes, as a measure to quantify the transition type. Finally, we parameterize the snow cover temperature along the avalanche track by the altitude Hs, which represents the point where the average temperature of the uppermost 0.5 m changes from cold to warm. We find that Ft is related to the snow cover properties, i.e. approximately proportional to Hs. Thus, the flow regime in the runout area and the type of transition can be predicted by knowing the snow cover temperature distribution. We find that, if Hs is more than 500 m above the valley floor for the path geometry of Vallée de la Sionne, entrainment of warm surface snow leads to a complete flow regime transition and the runout area is reached by only warm flow regimes. Such knowledge is of great importance since the impact pressure and the effectiveness of protection measures are greatly dependent on the flow regime. Article in Journal/Newspaper The Cryosphere Durham University: Durham Research Online The Cryosphere 12 12 3759 3774 |
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Open Polar |
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Durham University: Durham Research Online |
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ftunivdurham |
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unknown |
description |
Large avalanches usually encounter different snow conditions along their track. When they release as slab avalanches comprising cold snow, they can subsequently develop into powder snow avalanches entraining snow as they move down the mountain. Typically, this entrained snow will be cold (T¯¯¯<−1 ∘C) at high elevations near the surface, but warm (T¯¯¯>−1 ∘C) at lower elevations or deeper in the snowpack. The intake of warm snow is believed to be of major importance to increase the temperature of the snow composition in the avalanche and eventually cause a flow regime transition. Measurements of flow regime transitions are performed at the Vallée de la Sionne avalanche test site in Switzerland using two different radar systems. The data are then combined with snow temperatures calculated with the snow cover model SNOWPACK. We define transitions as complete when the deposit at runout is characterized only by warm snow or as partial if there is a warm flow regime, but the farthest deposit is characterized by cold snow. We introduce a transition index Ft, based on the runout of cold and warm flow regimes, as a measure to quantify the transition type. Finally, we parameterize the snow cover temperature along the avalanche track by the altitude Hs, which represents the point where the average temperature of the uppermost 0.5 m changes from cold to warm. We find that Ft is related to the snow cover properties, i.e. approximately proportional to Hs. Thus, the flow regime in the runout area and the type of transition can be predicted by knowing the snow cover temperature distribution. We find that, if Hs is more than 500 m above the valley floor for the path geometry of Vallée de la Sionne, entrainment of warm surface snow leads to a complete flow regime transition and the runout area is reached by only warm flow regimes. Such knowledge is of great importance since the impact pressure and the effectiveness of protection measures are greatly dependent on the flow regime. |
format |
Article in Journal/Newspaper |
author |
Köhler, Anselm Fischer, Jan-Thomas Scandroglio, Riccardo Bavay, Mathias McElwaine, Jim Sovilla, Betty |
spellingShingle |
Köhler, Anselm Fischer, Jan-Thomas Scandroglio, Riccardo Bavay, Mathias McElwaine, Jim Sovilla, Betty Cold-to-warm flow regime transition in snow avalanches. |
author_facet |
Köhler, Anselm Fischer, Jan-Thomas Scandroglio, Riccardo Bavay, Mathias McElwaine, Jim Sovilla, Betty |
author_sort |
Köhler, Anselm |
title |
Cold-to-warm flow regime transition in snow avalanches. |
title_short |
Cold-to-warm flow regime transition in snow avalanches. |
title_full |
Cold-to-warm flow regime transition in snow avalanches. |
title_fullStr |
Cold-to-warm flow regime transition in snow avalanches. |
title_full_unstemmed |
Cold-to-warm flow regime transition in snow avalanches. |
title_sort |
cold-to-warm flow regime transition in snow avalanches. |
publisher |
Copernicus Publications |
publishDate |
2018 |
url |
http://dro.dur.ac.uk/27002/ http://dro.dur.ac.uk/27002/1/27002.pdf https://doi.org/10.5194/tc-12-3759-2018 |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_source |
The cryosphere, 2018, Vol.12(12), pp.3759-3774 [Peer Reviewed Journal] |
op_relation |
dro:27002 issn:1994-0416 issn: 1994-0424 doi:10.5194/tc-12-3759-2018 http://dro.dur.ac.uk/27002/ https://doi.org/10.5194/tc-12-3759-2018 http://dro.dur.ac.uk/27002/1/27002.pdf |
op_rights |
© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-12-3759-2018 |
container_title |
The Cryosphere |
container_volume |
12 |
container_issue |
12 |
container_start_page |
3759 |
op_container_end_page |
3774 |
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1766216558035599360 |