Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling
Since permafrost in steep rockwalls is mainly climatically controlled, the ongoing climate warming potentially strongly impacts frequency and magnitude of rockfalls in high-alpine rock faces in the near future. However, knowledge about the role of permafrost is still limited. This is especially beca...
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ftunigrenoble:oai:HAL:halsde-00878144v1 2024-05-12T07:52:08+00:00 Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling Magnin, Florence Deline, Philip Ravanel, Ludovic Noetzli, Jeannette Environnements, Dynamiques et Territoires de Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) Glaciology, Geomorphodynamics and Geochronology Department of Geography Zürich Universität Zürich Zürich = University of Zurich (UZH)-Universität Zürich Zürich = University of Zurich (UZH) Vienne, Austria 2012 https://hal.science/halsde-00878144 en eng HAL CCSD halsde-00878144 https://hal.science/halsde-00878144 9th EGU General Assembly https://hal.science/halsde-00878144 9th EGU General Assembly, 2012, Vienne, Austria info:eu-repo/semantics/conferenceObject Conference papers 2012 ftunigrenoble 2024-04-18T02:12:58Z Since permafrost in steep rockwalls is mainly climatically controlled, the ongoing climate warming potentially strongly impacts frequency and magnitude of rockfalls in high-alpine rock faces in the near future. However, knowledge about the role of permafrost is still limited. This is especially because of measurement difficulties (invisibility of permafrost, remoteness and harshness in high mountain areas). In addition to local measurements, numerical models have thus been used in the past years to better understand the distribution and thermal conditions of permafrost and to investigate involved physical processes. To monitor permafrost in steep bedrock and to provide input and validation data for modeling, three 10-m- boreholes have been drilled in 2009 on the NW, NE and S faces of the Aiguille du Midi (AdM 3842 m a.s.l), a granitic peak in the Mont Blanc massif (France). Here, we study the thermal regimes at depth and heat diffusivity. Climatic parameters such as air temperature, wind speed and direction, incoming and outgoing solar radiations are also collected continuously by an automatic weather station. In this contribution, we present the first two years of data from the boreholes, in comparison with climatic parameters and outputs from a basic conductive 2D model. We gain a qualitative understanding of the processes governing the thermal regime of the central pillar of the Aiguille du Midi: (i) the importance of short-wave solar radiations on the most exposed rock faces, and air temperature control on other aspects, (ii) the impact of the snow cover, and (iii) the role of fractures on heat diffusivity and thermal regimes. 2010 and 2011 were respectively the coldest (mean annual air temperature: -9.1 C) and the warmest (-6.7 C) years since 2007 at the AdM. Solar radiations forcing is highlighted by fast thermal response of rockwalls experienced through the variation of the maximum Active Layer Thickness (ALT) from one year to another. In the SE face directly exposed to radiations, ALT was 2.7 m thicker ... Conference Object Active layer thickness permafrost Université Grenoble Alpes: HAL Mont Blanc ENVELOPE(69.468,69.468,-49.461,-49.461) Pillar ENVELOPE(166.217,166.217,-77.583,-77.583) |
institution |
Open Polar |
collection |
Université Grenoble Alpes: HAL |
op_collection_id |
ftunigrenoble |
language |
English |
description |
Since permafrost in steep rockwalls is mainly climatically controlled, the ongoing climate warming potentially strongly impacts frequency and magnitude of rockfalls in high-alpine rock faces in the near future. However, knowledge about the role of permafrost is still limited. This is especially because of measurement difficulties (invisibility of permafrost, remoteness and harshness in high mountain areas). In addition to local measurements, numerical models have thus been used in the past years to better understand the distribution and thermal conditions of permafrost and to investigate involved physical processes. To monitor permafrost in steep bedrock and to provide input and validation data for modeling, three 10-m- boreholes have been drilled in 2009 on the NW, NE and S faces of the Aiguille du Midi (AdM 3842 m a.s.l), a granitic peak in the Mont Blanc massif (France). Here, we study the thermal regimes at depth and heat diffusivity. Climatic parameters such as air temperature, wind speed and direction, incoming and outgoing solar radiations are also collected continuously by an automatic weather station. In this contribution, we present the first two years of data from the boreholes, in comparison with climatic parameters and outputs from a basic conductive 2D model. We gain a qualitative understanding of the processes governing the thermal regime of the central pillar of the Aiguille du Midi: (i) the importance of short-wave solar radiations on the most exposed rock faces, and air temperature control on other aspects, (ii) the impact of the snow cover, and (iii) the role of fractures on heat diffusivity and thermal regimes. 2010 and 2011 were respectively the coldest (mean annual air temperature: -9.1 C) and the warmest (-6.7 C) years since 2007 at the AdM. Solar radiations forcing is highlighted by fast thermal response of rockwalls experienced through the variation of the maximum Active Layer Thickness (ALT) from one year to another. In the SE face directly exposed to radiations, ALT was 2.7 m thicker ... |
author2 |
Environnements, Dynamiques et Territoires de Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) Glaciology, Geomorphodynamics and Geochronology Department of Geography Zürich Universität Zürich Zürich = University of Zurich (UZH)-Universität Zürich Zürich = University of Zurich (UZH) |
format |
Conference Object |
author |
Magnin, Florence Deline, Philip Ravanel, Ludovic Noetzli, Jeannette |
spellingShingle |
Magnin, Florence Deline, Philip Ravanel, Ludovic Noetzli, Jeannette Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling |
author_facet |
Magnin, Florence Deline, Philip Ravanel, Ludovic Noetzli, Jeannette |
author_sort |
Magnin, Florence |
title |
Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling |
title_short |
Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling |
title_full |
Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling |
title_fullStr |
Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling |
title_full_unstemmed |
Thermal regime in steep permafrost rockwalls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif) based on borehole data and 2D numerical modelling |
title_sort |
thermal regime in steep permafrost rockwalls (aiguille du midi, 3842 m a.s.l., mont blanc massif) based on borehole data and 2d numerical modelling |
publisher |
HAL CCSD |
publishDate |
2012 |
url |
https://hal.science/halsde-00878144 |
op_coverage |
Vienne, Austria |
long_lat |
ENVELOPE(69.468,69.468,-49.461,-49.461) ENVELOPE(166.217,166.217,-77.583,-77.583) |
geographic |
Mont Blanc Pillar |
geographic_facet |
Mont Blanc Pillar |
genre |
Active layer thickness permafrost |
genre_facet |
Active layer thickness permafrost |
op_source |
9th EGU General Assembly https://hal.science/halsde-00878144 9th EGU General Assembly, 2012, Vienne, Austria |
op_relation |
halsde-00878144 https://hal.science/halsde-00878144 |
_version_ |
1798841460665090048 |