气候变化领域集成服务门户(CCPortal): Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l)

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DOI	10.5194/tc-9-109-2015
	Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l)
	Magnin F.; Deline P.; Ravanel L.; Noetzli J.; Pogliotti P.
发表日期	2015
ISSN	19940416
卷号	9 期号:1
英文摘要	Permafrost and related thermo-hydro-mechanical processes are thought to influence high alpine rock wall stability, but a lack of field measurements means that the characteristics and processes of rock wall permafrost are poorly understood. To help remedy this situation, in 2005 work began to install a monitoring system at the Aiguille du Midi (3842 m a.s.l). This paper presents temperature records from nine surface sensors (eight years of records) and three 10 m deep boreholes (4 years of records), installed at locations with different surface and bedrock characteristics. In line with previous studies, our temperature data analyses showed that: micro-meteorology controls the surface temperature, active layer thicknesses are directly related to aspect and ranged from <2 m to nearly 6 m, and that thin accumulations of snow and open fractures are cooling factors. Thermal profiles empirically demonstrated the coexistence within a single rock peak of warm and cold permafrost (about g'1.5 to g'4.5 °C at 10 m depth) and the resulting lateral heat fluxes. Our results also extended current knowledge of the effect of snow, in that we found similar thermo-insulation effects as reported for gentle mountain areas. Thick snow warms shaded areas, and may reduce active layer refreezing in winter and delay its thawing in summer. However, thick snow thermo-insulation has little effect compared to the high albedo of snow which leads to cooler conditions at the rock surface in areas exposed to the sun. A consistent inflection in the thermal profiles reflected the cooling effect of an open fracture in the bedrock, which appeared to act as a thermal cutoff in the sub-surface thermal regime. Our field data are the first to be obtained from an Alpine permafrost site where borehole temperatures are below g'4 °C, and represent a first step towards the development of strategies to investigate poorly known aspects in steep bedrock permafrost such as the effects of snow cover and fractures. © Author(s) 2015.
学科领域	bedrock; fracture network; permafrost; snow cover; temperature gradient; thawing; Alps; Haute Savoie; Mont Blanc; Savoy Alps; Western Alps
语种	英语
scopus关键词	bedrock; fracture network; permafrost; snow cover; temperature gradient; thawing; Alps; Haute Savoie; Mont Blanc; Savoy Alps; Western Alps
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/119966
作者单位	EDYTEM Lab, Université de Savoie, CNRS, Le Bourget-du-Lac, France; Glaciology and Geomorphodynamics Group, Department of Geography, University of Zurich, Zurich, Switzerland; ARPA Valle d'Aosta, Saint-Christophe, Italy
推荐引用方式 GB/T 7714	Magnin F.,Deline P.,Ravanel L.,et al. Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l)[J],2015,9(1).
APA	Magnin F.,Deline P.,Ravanel L.,Noetzli J.,&Pogliotti P..(2015).Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l).Cryosphere,9(1).
MLA	Magnin F.,et al."Thermal characteristics of permafrost in the steep alpine rock walls of the Aiguille du Midi (Mont Blanc Massif, 3842 m a.s.l)".Cryosphere 9.1(2015).