Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimates
<p>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,...
Main Authors: | , , , |
---|---|
Format: | Article |
Language: | English |
Published: |
Copernicus Publications
2021-01-01
|
Series: | The Cryosphere |
Online Access: | https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf |
id |
doaj-57a08802df7743678bab513ead42c7ba |
---|---|
record_format |
Article |
spelling |
doaj-57a08802df7743678bab513ead42c7ba2021-01-19T12:49:10ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242021-01-011526528210.5194/tc-15-265-2021Debris cover and the thinning of Kennicott Glacier, Alaska: in situ measurements, automated ice cliff delineation and distributed melt estimatesL. S. Anderson0L. S. Anderson1W. H. Armstrong2W. H. Armstrong3R. S. Anderson4P. Buri5Department of Geological Sciences and Institute of Arctic and Alpine Research, University of Colorado Campus Box 450, Boulder, CO 80309-0450, USAGFZ German Research Centre for Geosciences, Telegrafenberg, 14473 Potsdam, GermanyDepartment of Geological Sciences and Institute of Arctic and Alpine Research, University of Colorado Campus Box 450, Boulder, CO 80309-0450, USADepartment of Geological and Environmental Sciences, Appalachian State University, 033 Rankin Science West, ASU Box 32067, Boone, NC 28608-2067, USADepartment of Geological Sciences and Institute of Arctic and Alpine Research, University of Colorado Campus Box 450, Boulder, CO 80309-0450, USAGeophysical Institute, University of Alaska-Fairbanks, 2156 Koyukuk Drive, Fairbanks, AK 99775, USA<p>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.</p> <p>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 km<span class="inline-formula"><sup>2</sup></span> of the 387 km<span class="inline-formula"><sup>2</sup></span> 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.</p> <p>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 <i>relative</i> importance of ice cliffs to area-average melt is significant, the <i>absolute</i> area-averaged melt is dominated by debris.</p> <p>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.</p>https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf |
collection |
DOAJ |
language |
English |
format |
Article |
sources |
DOAJ |
author |
L. S. Anderson L. S. Anderson W. H. Armstrong W. H. Armstrong R. S. Anderson P. Buri |
spellingShingle |
L. S. Anderson L. S. Anderson W. H. Armstrong 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 The Cryosphere |
author_facet |
L. S. Anderson L. S. Anderson W. H. Armstrong 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 |
series |
The Cryosphere |
issn |
1994-0416 1994-0424 |
publishDate |
2021-01-01 |
description |
<p>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.</p>
<p>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 km<span class="inline-formula"><sup>2</sup></span> of the
387 km<span class="inline-formula"><sup>2</sup></span> 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.</p>
<p>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 <i>relative</i> importance of ice cliffs to area-average
melt is significant, the <i>absolute</i> area-averaged melt is dominated by debris.</p>
<p>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.</p> |
url |
https://tc.copernicus.org/articles/15/265/2021/tc-15-265-2021.pdf |
work_keys_str_mv |
AT lsanderson debriscoverandthethinningofkennicottglacieralaskainsitumeasurementsautomatedicecliffdelineationanddistributedmeltestimates AT lsanderson debriscoverandthethinningofkennicottglacieralaskainsitumeasurementsautomatedicecliffdelineationanddistributedmeltestimates AT wharmstrong debriscoverandthethinningofkennicottglacieralaskainsitumeasurementsautomatedicecliffdelineationanddistributedmeltestimates AT wharmstrong debriscoverandthethinningofkennicottglacieralaskainsitumeasurementsautomatedicecliffdelineationanddistributedmeltestimates AT rsanderson debriscoverandthethinningofkennicottglacieralaskainsitumeasurementsautomatedicecliffdelineationanddistributedmeltestimates AT pburi debriscoverandthethinningofkennicottglacieralaskainsitumeasurementsautomatedicecliffdelineationanddistributedmeltestimates |
_version_ |
1724331817856663552 |