Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland
Abstract Firn-density variations have been studied in the lower accumulation area of the Greenland ice sheet (1440-1620 m a.s.l.) near Pâkitsoq, West Greenland. The main control on density in the near-surface firn layer (of 5-10 m thickness) is the formation of ice layers by the refreezing of meltwa...
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Language: | English |
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Cambridge University Press (CUP)
1994
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Online Access: | http://dx.doi.org/10.1017/s002214300001234x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300001234X |
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crcambridgeupr:10.1017/s002214300001234x 2024-06-16T07:40:19+00:00 Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland Braithwaite, Roger J. Laternser, Martin Pfeffer, W. Tad 1994 http://dx.doi.org/10.1017/s002214300001234x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300001234X en eng Cambridge University Press (CUP) Journal of Glaciology volume 40, issue 136, page 477-485 ISSN 0022-1430 1727-5652 journal-article 1994 crcambridgeupr https://doi.org/10.1017/s002214300001234x 2024-05-22T12:56:39Z Abstract Firn-density variations have been studied in the lower accumulation area of the Greenland ice sheet (1440-1620 m a.s.l.) near Pâkitsoq, West Greenland. The main control on density in the near-surface firn layer (of 5-10 m thickness) is the formation of ice layers by the refreezing of meltwater that reaches depths of 2-4 m below the surface. The density variations are described by the ratio of annual surface melt M to the annual accumulation C . The ratio M/C is about 0.6 at the run-off limit (at about 1400 m a.s.l. in the study area) where refreezing of meltwater transforms snow into impermeable ice. The mean density of near-surface firn decreases with elevation, reflecting a decrease in melt with elevation. There is a surprising decrease in firn density at depths of more than about 4 m below the 1991 summer surface, which reflects lower melt rates and/or higher accumulation in the early 1980s and late 1970s when this firn was passing through the surface layer. The formation of such low-density firn may have partially contributed to the 1978-85 thickening of the ice sheet observed by satellite-radar altimetry. Near-surface firn density is therefore very sensitive to climate change and might be an attractive target for climate monitoring. Article in Journal/Newspaper Greenland Ice Sheet Journal of Glaciology Cambridge University Press Greenland Journal of Glaciology 40 136 477 485 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract Firn-density variations have been studied in the lower accumulation area of the Greenland ice sheet (1440-1620 m a.s.l.) near Pâkitsoq, West Greenland. The main control on density in the near-surface firn layer (of 5-10 m thickness) is the formation of ice layers by the refreezing of meltwater that reaches depths of 2-4 m below the surface. The density variations are described by the ratio of annual surface melt M to the annual accumulation C . The ratio M/C is about 0.6 at the run-off limit (at about 1400 m a.s.l. in the study area) where refreezing of meltwater transforms snow into impermeable ice. The mean density of near-surface firn decreases with elevation, reflecting a decrease in melt with elevation. There is a surprising decrease in firn density at depths of more than about 4 m below the 1991 summer surface, which reflects lower melt rates and/or higher accumulation in the early 1980s and late 1970s when this firn was passing through the surface layer. The formation of such low-density firn may have partially contributed to the 1978-85 thickening of the ice sheet observed by satellite-radar altimetry. Near-surface firn density is therefore very sensitive to climate change and might be an attractive target for climate monitoring. |
format |
Article in Journal/Newspaper |
author |
Braithwaite, Roger J. Laternser, Martin Pfeffer, W. Tad |
spellingShingle |
Braithwaite, Roger J. Laternser, Martin Pfeffer, W. Tad Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland |
author_facet |
Braithwaite, Roger J. Laternser, Martin Pfeffer, W. Tad |
author_sort |
Braithwaite, Roger J. |
title |
Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland |
title_short |
Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland |
title_full |
Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland |
title_fullStr |
Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland |
title_full_unstemmed |
Variations of near-surface firn density in the lower accumulation area of the Greenland ice sheet, Pâkitsoq, West Greenland |
title_sort |
variations of near-surface firn density in the lower accumulation area of the greenland ice sheet, pâkitsoq, west greenland |
publisher |
Cambridge University Press (CUP) |
publishDate |
1994 |
url |
http://dx.doi.org/10.1017/s002214300001234x https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S002214300001234X |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet Journal of Glaciology |
genre_facet |
Greenland Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 40, issue 136, page 477-485 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s002214300001234x |
container_title |
Journal of Glaciology |
container_volume |
40 |
container_issue |
136 |
container_start_page |
477 |
op_container_end_page |
485 |
_version_ |
1802007216391192576 |