Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif).
International audience Since the early 2000s, a remarkable amount of rockfalls has been observed in permafrost areas of the mid-latitude mountain ranges concurrently to hot summers. This study explores the seasonal thaw (ST) in permafrost rock walls of the Aiguille du Midi site (3842 m a.s.l., Mont...
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Online Access: | https://hal-sde.archives-ouvertes.fr/hal-01781533 |
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ftccsdartic:oai:HAL:hal-01781533v1 2023-05-15T13:03:21+02:00 Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). Magnin, Florence Westermann, Sebastien Pogliotti, Paolo Ravanel, Ludovic Deline, Philip Environnements, Dynamiques et Territoires de la Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) Department of Geosciences Oslo Faculty of Mathematics and Natural Sciences Oslo University of Oslo (UiO)-University of Oslo (UiO) ARPA Valle d'Aosta (Aosta Valley Regional Environmental Protection Agency) Aosta Valley Regional Environmental Protection Agency (ARPA) Société Préhistorique Française Chambéry, France 2016-06-27 https://hal-sde.archives-ouvertes.fr/hal-01781533 en eng HAL CCSD hal-01781533 https://hal-sde.archives-ouvertes.fr/hal-01781533 18th Joint Geomorphological Meeting https://hal-sde.archives-ouvertes.fr/hal-01781533 18th Joint Geomorphological Meeting, Société Préhistorique Française, Jun 2016, Chambéry, France [SDE]Environmental Sciences info:eu-repo/semantics/conferenceObject Conference papers 2016 ftccsdartic 2021-12-26T00:01:34Z International audience Since the early 2000s, a remarkable amount of rockfalls has been observed in permafrost areas of the mid-latitude mountain ranges concurrently to hot summers. This study explores the seasonal thaw (ST) in permafrost rock walls of the Aiguille du Midi site (3842 m a.s.l., Mont Blanc massif). We first analyse six years of temperature records in three 10 m-deep boreholes against air temperature (AT) and a four-year time series of pictures showing the snow conditions on two rock faces. Then, we test the sensitivity of the active layer against eight snow fall scenarios using the 1-D surface energy balance and heat conduction model CryoGrid 3 forced by in-situ measurements from a vertical face. Snow falls occur all the year round at this elevation and play an important role for the active layer thickness (ALT), but the snow cover and its control are highly heterogeneous. A long-lasting of a snow cover during spring/early summer delays the ST and reduces the ALT. The thicker and the more spatially-continuous is the snow cover, the stronger are the delay and ALT reduction. Convective clouds could also reinforce this pattern. The summer AT and heat waves are the dominant controlling factors of the ALT. But summer snow falls can sometimes persist for several days on the rock surface and reduce the effect of the heat waves. Active layer can thicken during the early fall, except if the snow starts to accumulate on the rock surface and favours the refreezing. The timing of the snow fall is the most critical parameter to determine the snow effect on the ALT. This study suggests that the characteristics of the bedrock and snow accumulation (steepness, surface roughness, and sun-exposure) must be taken into account to better understand the formation and changes of the active layer and its possible implications for rockfall triggering. Conference Object Active layer thickness permafrost Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) Mont Blanc ENVELOPE(69.468,69.468,-49.461,-49.461) |
institution |
Open Polar |
collection |
Archive ouverte HAL (Hyper Article en Ligne, CCSD - Centre pour la Communication Scientifique Directe) |
op_collection_id |
ftccsdartic |
language |
English |
topic |
[SDE]Environmental Sciences |
spellingShingle |
[SDE]Environmental Sciences Magnin, Florence Westermann, Sebastien Pogliotti, Paolo Ravanel, Ludovic Deline, Philip Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). |
topic_facet |
[SDE]Environmental Sciences |
description |
International audience Since the early 2000s, a remarkable amount of rockfalls has been observed in permafrost areas of the mid-latitude mountain ranges concurrently to hot summers. This study explores the seasonal thaw (ST) in permafrost rock walls of the Aiguille du Midi site (3842 m a.s.l., Mont Blanc massif). We first analyse six years of temperature records in three 10 m-deep boreholes against air temperature (AT) and a four-year time series of pictures showing the snow conditions on two rock faces. Then, we test the sensitivity of the active layer against eight snow fall scenarios using the 1-D surface energy balance and heat conduction model CryoGrid 3 forced by in-situ measurements from a vertical face. Snow falls occur all the year round at this elevation and play an important role for the active layer thickness (ALT), but the snow cover and its control are highly heterogeneous. A long-lasting of a snow cover during spring/early summer delays the ST and reduces the ALT. The thicker and the more spatially-continuous is the snow cover, the stronger are the delay and ALT reduction. Convective clouds could also reinforce this pattern. The summer AT and heat waves are the dominant controlling factors of the ALT. But summer snow falls can sometimes persist for several days on the rock surface and reduce the effect of the heat waves. Active layer can thicken during the early fall, except if the snow starts to accumulate on the rock surface and favours the refreezing. The timing of the snow fall is the most critical parameter to determine the snow effect on the ALT. This study suggests that the characteristics of the bedrock and snow accumulation (steepness, surface roughness, and sun-exposure) must be taken into account to better understand the formation and changes of the active layer and its possible implications for rockfall triggering. |
author2 |
Environnements, Dynamiques et Territoires de la Montagne (EDYTEM) Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS) Department of Geosciences Oslo Faculty of Mathematics and Natural Sciences Oslo University of Oslo (UiO)-University of Oslo (UiO) ARPA Valle d'Aosta (Aosta Valley Regional Environmental Protection Agency) Aosta Valley Regional Environmental Protection Agency (ARPA) Société Préhistorique Française |
format |
Conference Object |
author |
Magnin, Florence Westermann, Sebastien Pogliotti, Paolo Ravanel, Ludovic Deline, Philip |
author_facet |
Magnin, Florence Westermann, Sebastien Pogliotti, Paolo Ravanel, Ludovic Deline, Philip |
author_sort |
Magnin, Florence |
title |
Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). |
title_short |
Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). |
title_full |
Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). |
title_fullStr |
Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). |
title_full_unstemmed |
Snow control on active layer thickness in steep alpine rock walls (Aiguille du Midi, 3842 m a.s.l., Mont Blanc massif). |
title_sort |
snow control on active layer thickness in steep alpine rock walls (aiguille du midi, 3842 m a.s.l., mont blanc massif). |
publisher |
HAL CCSD |
publishDate |
2016 |
url |
https://hal-sde.archives-ouvertes.fr/hal-01781533 |
op_coverage |
Chambéry, France |
long_lat |
ENVELOPE(69.468,69.468,-49.461,-49.461) |
geographic |
Mont Blanc |
geographic_facet |
Mont Blanc |
genre |
Active layer thickness permafrost |
genre_facet |
Active layer thickness permafrost |
op_source |
18th Joint Geomorphological Meeting https://hal-sde.archives-ouvertes.fr/hal-01781533 18th Joint Geomorphological Meeting, Société Préhistorique Française, Jun 2016, Chambéry, France |
op_relation |
hal-01781533 https://hal-sde.archives-ouvertes.fr/hal-01781533 |
_version_ |
1766334802035736576 |