Formation of glacier tables caused by differential ice melting: field observation and modelling
Glacier tables are structures frequently encountered on temperate glaciers. They consist of a rock supported by a narrow ice foot which forms through differential melting of the ice. In this article, we investigate their formation by following their dynamics on the Mer de Glace (the Alps, France). W...
Published in: | The Cryosphere |
---|---|
Main Authors: | , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Copernicus Publications
2022
|
Subjects: | |
Online Access: | https://doi.org/10.5194/tc-16-2617-2022 https://noa.gwlb.de/receive/cop_mods_00061693 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00061113/tc-16-2617-2022.pdf https://tc.copernicus.org/articles/16/2617/2022/tc-16-2617-2022.pdf |
id |
ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00061693 |
---|---|
record_format |
openpolar |
spelling |
ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00061693 2023-05-15T18:32:33+02:00 Formation of glacier tables caused by differential ice melting: field observation and modelling Hénot, Marceau Langlois, Vincent J. Vessaire, Jérémy Plihon, Nicolas Taberlet, Nicolas 2022-06 electronic https://doi.org/10.5194/tc-16-2617-2022 https://noa.gwlb.de/receive/cop_mods_00061693 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00061113/tc-16-2617-2022.pdf https://tc.copernicus.org/articles/16/2617/2022/tc-16-2617-2022.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-16-2617-2022 https://noa.gwlb.de/receive/cop_mods_00061693 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00061113/tc-16-2617-2022.pdf https://tc.copernicus.org/articles/16/2617/2022/tc-16-2617-2022.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2022 ftnonlinearchiv https://doi.org/10.5194/tc-16-2617-2022 2022-07-03T23:11:41Z Glacier tables are structures frequently encountered on temperate glaciers. They consist of a rock supported by a narrow ice foot which forms through differential melting of the ice. In this article, we investigate their formation by following their dynamics on the Mer de Glace (the Alps, France). We report field measurements of four specific glacier tables over the course of several days, as well as snapshot measurements of a field of 80 tables performed on a given day. We develop a simple model accounting for the various mechanisms of the heat transfer on the glacier using local meteorological data, which displays a quantitative agreement with the field measurements. We show that the formation of glacier tables is controlled by the global heat flux received by the rocks, which causes the ice underneath to melt at a rate proportional to the one of the surrounding ice. Under large rocks the ice ablation rate is reduced compared to bare ice, leading to the formation of glacier tables. This thermal insulation effect is due to the warmer surface temperature of rocks compared to the ice, which affects the net long-wave and turbulent fluxes. While the short-wave radiation, which is the main source of heat, is slightly more absorbed by the rocks than the ice, it plays an indirect role in the insulation by inducing a thermal gradient across the rocks which warms them. Under a critical size, however, rocks can enhance ice melting and consequently sink into the ice surface. This happens when the insulation effect is too weak to compensate for a geometrical amplification effect: the external heat fluxes are received on a larger surface than the contact area with the ice. We identified the main parameters controlling the ability of a rock to form a glacier table: the rock thickness, its aspect ratio, and the ratio between the averaged turbulent and short-wave heat fluxes. Article in Journal/Newspaper The Cryosphere Niedersächsisches Online-Archiv NOA The Cryosphere 16 6 2617 2628 |
institution |
Open Polar |
collection |
Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Hénot, Marceau Langlois, Vincent J. Vessaire, Jérémy Plihon, Nicolas Taberlet, Nicolas Formation of glacier tables caused by differential ice melting: field observation and modelling |
topic_facet |
article Verlagsveröffentlichung |
description |
Glacier tables are structures frequently encountered on temperate glaciers. They consist of a rock supported by a narrow ice foot which forms through differential melting of the ice. In this article, we investigate their formation by following their dynamics on the Mer de Glace (the Alps, France). We report field measurements of four specific glacier tables over the course of several days, as well as snapshot measurements of a field of 80 tables performed on a given day. We develop a simple model accounting for the various mechanisms of the heat transfer on the glacier using local meteorological data, which displays a quantitative agreement with the field measurements. We show that the formation of glacier tables is controlled by the global heat flux received by the rocks, which causes the ice underneath to melt at a rate proportional to the one of the surrounding ice. Under large rocks the ice ablation rate is reduced compared to bare ice, leading to the formation of glacier tables. This thermal insulation effect is due to the warmer surface temperature of rocks compared to the ice, which affects the net long-wave and turbulent fluxes. While the short-wave radiation, which is the main source of heat, is slightly more absorbed by the rocks than the ice, it plays an indirect role in the insulation by inducing a thermal gradient across the rocks which warms them. Under a critical size, however, rocks can enhance ice melting and consequently sink into the ice surface. This happens when the insulation effect is too weak to compensate for a geometrical amplification effect: the external heat fluxes are received on a larger surface than the contact area with the ice. We identified the main parameters controlling the ability of a rock to form a glacier table: the rock thickness, its aspect ratio, and the ratio between the averaged turbulent and short-wave heat fluxes. |
format |
Article in Journal/Newspaper |
author |
Hénot, Marceau Langlois, Vincent J. Vessaire, Jérémy Plihon, Nicolas Taberlet, Nicolas |
author_facet |
Hénot, Marceau Langlois, Vincent J. Vessaire, Jérémy Plihon, Nicolas Taberlet, Nicolas |
author_sort |
Hénot, Marceau |
title |
Formation of glacier tables caused by differential ice melting: field observation and modelling |
title_short |
Formation of glacier tables caused by differential ice melting: field observation and modelling |
title_full |
Formation of glacier tables caused by differential ice melting: field observation and modelling |
title_fullStr |
Formation of glacier tables caused by differential ice melting: field observation and modelling |
title_full_unstemmed |
Formation of glacier tables caused by differential ice melting: field observation and modelling |
title_sort |
formation of glacier tables caused by differential ice melting: field observation and modelling |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-2617-2022 https://noa.gwlb.de/receive/cop_mods_00061693 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00061113/tc-16-2617-2022.pdf https://tc.copernicus.org/articles/16/2617/2022/tc-16-2617-2022.pdf |
genre |
The Cryosphere |
genre_facet |
The Cryosphere |
op_relation |
The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-16-2617-2022 https://noa.gwlb.de/receive/cop_mods_00061693 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00061113/tc-16-2617-2022.pdf https://tc.copernicus.org/articles/16/2617/2022/tc-16-2617-2022.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-16-2617-2022 |
container_title |
The Cryosphere |
container_volume |
16 |
container_issue |
6 |
container_start_page |
2617 |
op_container_end_page |
2628 |
_version_ |
1766216731778351104 |