Dark ice dynamics of the south-west Greenland Ice Sheet
Runoff from the Greenland Ice Sheet (GrIS) has increased in recent years due largely to changes in atmospheric circulation and atmospheric warming. Albedo reductions resulting from these changes have amplified surface melting. Some of the largest declines in GrIS albedo have occurred in the ablation...
Published in: | The Cryosphere |
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Language: | English |
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Copernicus Publications
2017
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00008222 2023-05-15T16:29:07+02:00 Dark ice dynamics of the south-west Greenland Ice Sheet Tedstone, Andrew J. Bamber, Jonathan L. Cook, Joseph M. Williamson, Christopher J. Fettweis, Xavier Hodson, Andrew J. Tranter, Martyn 2017-11 electronic https://doi.org/10.5194/tc-11-2491-2017 https://noa.gwlb.de/receive/cop_mods_00008222 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00008179/tc-11-2491-2017.pdf https://tc.copernicus.org/articles/11/2491/2017/tc-11-2491-2017.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-11-2491-2017 https://noa.gwlb.de/receive/cop_mods_00008222 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00008179/tc-11-2491-2017.pdf https://tc.copernicus.org/articles/11/2491/2017/tc-11-2491-2017.pdf uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2017 ftnonlinearchiv https://doi.org/10.5194/tc-11-2491-2017 2022-02-08T22:58:07Z Runoff from the Greenland Ice Sheet (GrIS) has increased in recent years due largely to changes in atmospheric circulation and atmospheric warming. Albedo reductions resulting from these changes have amplified surface melting. Some of the largest declines in GrIS albedo have occurred in the ablation zone of the south-west sector and are associated with the development of dark ice surfaces. Field observations at local scales reveal that a variety of light-absorbing impurities (LAIs) can be present on the surface, ranging from inorganic particulates to cryoconite materials and ice algae. Meanwhile, satellite observations show that the areal extent of dark ice has varied significantly between recent successive melt seasons. However, the processes that drive such large interannual variability in dark ice extent remain essentially unconstrained. At present we are therefore unable to project how the albedo of bare ice sectors of the GrIS will evolve in the future, causing uncertainty in the projected sea level contribution from the GrIS over the coming decades. Here we use MODIS satellite imagery to examine dark ice dynamics on the south-west GrIS each year from 2000 to 2016. We quantify dark ice in terms of its annual extent, duration, intensity and timing of first appearance. Not only does dark ice extent vary significantly between years but so too does its duration (from 0 to > 80 % of June–July–August, JJA), intensity and the timing of its first appearance. Comparison of dark ice dynamics with potential meteorological drivers from the regional climate model MAR reveals that the JJA sensible heat flux, the number of positive minimum-air-temperature days and the timing of bare ice appearance are significant interannual synoptic controls. We use these findings to identify the surface processes which are most likely to explain recent dark ice dynamics. We suggest that whilst the spatial distribution of dark ice is best explained by outcropping of particulates from ablating ice, these particulates alone do not drive dark ice dynamics. Instead, they may enable the growth of pigmented ice algal assemblages which cause visible surface darkening, but only when the climatological prerequisites of liquid meltwater presence and sufficient photosynthetically active radiation fluxes are met. Further field studies are required to fully constrain the processes by which ice algae growth proceeds and the apparent dependency of algae growth on melt-out particulates. Article in Journal/Newspaper Greenland ice algae Ice Sheet The Cryosphere Niedersächsisches Online-Archiv NOA Greenland The Cryosphere 11 6 2491 2506 |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Tedstone, Andrew J. Bamber, Jonathan L. Cook, Joseph M. Williamson, Christopher J. Fettweis, Xavier Hodson, Andrew J. Tranter, Martyn Dark ice dynamics of the south-west Greenland Ice Sheet |
topic_facet |
article Verlagsveröffentlichung |
description |
Runoff from the Greenland Ice Sheet (GrIS) has increased in recent years due largely to changes in atmospheric circulation and atmospheric warming. Albedo reductions resulting from these changes have amplified surface melting. Some of the largest declines in GrIS albedo have occurred in the ablation zone of the south-west sector and are associated with the development of dark ice surfaces. Field observations at local scales reveal that a variety of light-absorbing impurities (LAIs) can be present on the surface, ranging from inorganic particulates to cryoconite materials and ice algae. Meanwhile, satellite observations show that the areal extent of dark ice has varied significantly between recent successive melt seasons. However, the processes that drive such large interannual variability in dark ice extent remain essentially unconstrained. At present we are therefore unable to project how the albedo of bare ice sectors of the GrIS will evolve in the future, causing uncertainty in the projected sea level contribution from the GrIS over the coming decades. Here we use MODIS satellite imagery to examine dark ice dynamics on the south-west GrIS each year from 2000 to 2016. We quantify dark ice in terms of its annual extent, duration, intensity and timing of first appearance. Not only does dark ice extent vary significantly between years but so too does its duration (from 0 to > 80 % of June–July–August, JJA), intensity and the timing of its first appearance. Comparison of dark ice dynamics with potential meteorological drivers from the regional climate model MAR reveals that the JJA sensible heat flux, the number of positive minimum-air-temperature days and the timing of bare ice appearance are significant interannual synoptic controls. We use these findings to identify the surface processes which are most likely to explain recent dark ice dynamics. We suggest that whilst the spatial distribution of dark ice is best explained by outcropping of particulates from ablating ice, these particulates alone do not drive dark ice dynamics. Instead, they may enable the growth of pigmented ice algal assemblages which cause visible surface darkening, but only when the climatological prerequisites of liquid meltwater presence and sufficient photosynthetically active radiation fluxes are met. Further field studies are required to fully constrain the processes by which ice algae growth proceeds and the apparent dependency of algae growth on melt-out particulates. |
format |
Article in Journal/Newspaper |
author |
Tedstone, Andrew J. Bamber, Jonathan L. Cook, Joseph M. Williamson, Christopher J. Fettweis, Xavier Hodson, Andrew J. Tranter, Martyn |
author_facet |
Tedstone, Andrew J. Bamber, Jonathan L. Cook, Joseph M. Williamson, Christopher J. Fettweis, Xavier Hodson, Andrew J. Tranter, Martyn |
author_sort |
Tedstone, Andrew J. |
title |
Dark ice dynamics of the south-west Greenland Ice Sheet |
title_short |
Dark ice dynamics of the south-west Greenland Ice Sheet |
title_full |
Dark ice dynamics of the south-west Greenland Ice Sheet |
title_fullStr |
Dark ice dynamics of the south-west Greenland Ice Sheet |
title_full_unstemmed |
Dark ice dynamics of the south-west Greenland Ice Sheet |
title_sort |
dark ice dynamics of the south-west greenland ice sheet |
publisher |
Copernicus Publications |
publishDate |
2017 |
url |
https://doi.org/10.5194/tc-11-2491-2017 https://noa.gwlb.de/receive/cop_mods_00008222 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00008179/tc-11-2491-2017.pdf https://tc.copernicus.org/articles/11/2491/2017/tc-11-2491-2017.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland ice algae Ice Sheet The Cryosphere |
genre_facet |
Greenland ice algae Ice Sheet 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-11-2491-2017 https://noa.gwlb.de/receive/cop_mods_00008222 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00008179/tc-11-2491-2017.pdf https://tc.copernicus.org/articles/11/2491/2017/tc-11-2491-2017.pdf |
op_rights |
uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-11-2491-2017 |
container_title |
The Cryosphere |
container_volume |
11 |
container_issue |
6 |
container_start_page |
2491 |
op_container_end_page |
2506 |
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1766018807234560000 |