气候变化领域集成服务门户(CCPortal): Cold-To-warm flow regime transition in snow avalanches

CCPortal

DOI	10.5194/tc-12-3759-2018
	Cold-To-warm flow regime transition in snow avalanches
	Köhler A.; Fischer J.-T.; Scandroglio R.; Bavay M.; McElwaine J.; Sovilla B.
发表日期	2018
ISSN	19940416
卷号	12 期号:12
英文摘要	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 0.5m 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 500m 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. © 2018 Copernicus GmbH. All rights reserved.
学科领域	entrainment; parameterization; radar; snow avalanche; snow cover; snowpack; temperature; Sionne Valley; Switzerland; Valais
语种	英语
scopus关键词	entrainment; parameterization; radar; snow avalanche; snow cover; snowpack; temperature; Sionne Valley; Switzerland; Valais
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/119021
作者单位	WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland; Austrian Research Centre for Forests (BFW), Innsbruck, Austria; Department of Earth Sciences, Durham University, Durham, United Kingdom
推荐引用方式 GB/T 7714	Köhler A.,Fischer J.-T.,Scandroglio R.,et al. Cold-To-warm flow regime transition in snow avalanches[J],2018,12(12).
APA	Köhler A.,Fischer J.-T.,Scandroglio R.,Bavay M.,McElwaine J.,&Sovilla B..(2018).Cold-To-warm flow regime transition in snow avalanches.Cryosphere,12(12).
MLA	Köhler A.,et al."Cold-To-warm flow regime transition in snow avalanches".Cryosphere 12.12(2018).