Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates
Many glaciers are thinning rapidly beneath melt-reducing debris cover, including Kennicott Glacier in Alaska where glacier-wide maximum thinning also occurs under debris. This contradiction has been explained by melt hotspots, such as ice cliffs, scattered within the debris cover. However, melt hots...
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Online Access: | https://doi.org/10.5194/tc-15-265-2021 https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf https://doaj.org/article/57a08802df7743678bab513ead42c7ba |
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fttriple:oai:gotriple.eu:oai:doaj.org/article:57a08802df7743678bab513ead42c7ba 2023-05-15T16:20:10+02:00 Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates L. S. Anderson W. H. Armstrong R. S. Anderson P. Buri 2021-01-01 https://doi.org/10.5194/tc-15-265-2021 https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf https://doaj.org/article/57a08802df7743678bab513ead42c7ba en eng Copernicus Publications doi:10.5194/tc-15-265-2021 1994-0416 1994-0424 https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf https://doaj.org/article/57a08802df7743678bab513ead42c7ba undefined The Cryosphere, Vol 15, Pp 265-282 (2021) geo envir Journal Article https://vocabularies.coar-repositories.org/resource_types/c_6501/ 2021 fttriple https://doi.org/10.5194/tc-15-265-2021 2023-01-22T19:11:27Z Many glaciers are thinning rapidly beneath melt-reducing debris cover, including Kennicott Glacier in Alaska where glacier-wide maximum thinning also occurs under debris. This contradiction has been explained by melt hotspots, such as ice cliffs, scattered within the debris cover. However, melt hotspots alone cannot account for the rapid thinning at Kennicott Glacier. We consider the significance of ice cliffs, debris, and ice dynamics in addressing this outstanding problem. We collected abundant in situ measurements of debris thickness, sub-debris melt, and ice cliff backwasting, allowing for extrapolation across the debris-covered tongue (the study area and the lower 24.2 km2 of the 387 km2 glacier). A newly developed automatic ice cliff delineation method is the first to use only optical satellite imagery. The adaptive binary threshold method accurately estimates ice cliff coverage even where ice cliffs are small and debris color varies. Kennicott Glacier exhibits the highest fractional area of ice cliffs (11.7 %) documented to date. Ice cliffs contribute 26 % of total melt across the glacier tongue. Although the relative importance of ice cliffs to area-average melt is significant, the absolute area-averaged melt is dominated by debris. At Kennicott Glacier, glacier-wide melt rates are not maximized in the zone of maximum thinning. Declining ice discharge through time therefore explains the rapid thinning. There is more debris-covered ice in Alaska than in any other region on Earth. Through this study, Kennicott Glacier is the first glacier in Alaska, and the largest glacier globally, where melt across its debris-covered tongue has been rigorously quantified. Article in Journal/Newspaper glacier glaciers The Cryosphere Alaska Unknown The Cryosphere 15 1 265 282 |
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geo envir L. S. Anderson W. H. Armstrong R. S. Anderson P. Buri Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
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geo envir |
description |
Many glaciers are thinning rapidly beneath melt-reducing debris cover, including Kennicott Glacier in Alaska where glacier-wide maximum thinning also occurs under debris. This contradiction has been explained by melt hotspots, such as ice cliffs, scattered within the debris cover. However, melt hotspots alone cannot account for the rapid thinning at Kennicott Glacier. We consider the significance of ice cliffs, debris, and ice dynamics in addressing this outstanding problem. We collected abundant in situ measurements of debris thickness, sub-debris melt, and ice cliff backwasting, allowing for extrapolation across the debris-covered tongue (the study area and the lower 24.2 km2 of the 387 km2 glacier). A newly developed automatic ice cliff delineation method is the first to use only optical satellite imagery. The adaptive binary threshold method accurately estimates ice cliff coverage even where ice cliffs are small and debris color varies. Kennicott Glacier exhibits the highest fractional area of ice cliffs (11.7 %) documented to date. Ice cliffs contribute 26 % of total melt across the glacier tongue. Although the relative importance of ice cliffs to area-average melt is significant, the absolute area-averaged melt is dominated by debris. At Kennicott Glacier, glacier-wide melt rates are not maximized in the zone of maximum thinning. Declining ice discharge through time therefore explains the rapid thinning. There is more debris-covered ice in Alaska than in any other region on Earth. Through this study, Kennicott Glacier is the first glacier in Alaska, and the largest glacier globally, where melt across its debris-covered tongue has been rigorously quantified. |
format |
Article in Journal/Newspaper |
author |
L. S. Anderson W. H. Armstrong R. S. Anderson P. Buri |
author_facet |
L. S. Anderson W. H. Armstrong R. S. Anderson P. Buri |
author_sort |
L. S. Anderson |
title |
Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
title_short |
Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
title_full |
Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
title_fullStr |
Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
title_full_unstemmed |
Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
title_sort |
debris cover and the thinning of kennicott glacier, alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates |
publisher |
Copernicus Publications |
publishDate |
2021 |
url |
https://doi.org/10.5194/tc-15-265-2021 https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf https://doaj.org/article/57a08802df7743678bab513ead42c7ba |
genre |
glacier glaciers The Cryosphere Alaska |
genre_facet |
glacier glaciers The Cryosphere Alaska |
op_source |
The Cryosphere, Vol 15, Pp 265-282 (2021) |
op_relation |
doi:10.5194/tc-15-265-2021 1994-0416 1994-0424 https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf https://doaj.org/article/57a08802df7743678bab513ead42c7ba |
op_rights |
undefined |
op_doi |
https://doi.org/10.5194/tc-15-265-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
1 |
container_start_page |
265 |
op_container_end_page |
282 |
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