Climatic control on seasonal variations in mountain glacier surface velocity
<p>Accurate measurements of ice flow are essential to predict future changes in glaciers and ice caps. Glacier displacement can in principle be measured on the large scale by cross-correlation of satellite images. At weekly to monthly scales, the expected displacement is often of the same orde...
| Main Authors: | , , , , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2023-04-01
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| Series: | The Cryosphere |
| Online Access: | https://tc.copernicus.org/articles/17/1567/2023/tc-17-1567-2023.pdf |
| _version_ | 1797848815275868160 |
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| author | U. Nanni U. Nanni D. Scherler D. Scherler F. Ayoub R. Millan F. Herman J.-P. Avouac |
| author_facet | U. Nanni U. Nanni D. Scherler D. Scherler F. Ayoub R. Millan F. Herman J.-P. Avouac |
| author_sort | U. Nanni |
| collection | DOAJ |
| description | <p>Accurate measurements of ice flow are essential to predict future changes in
glaciers and ice caps. Glacier displacement can in principle be measured on
the large scale by cross-correlation of satellite images. At weekly to
monthly scales, the expected displacement is often of the same order as the
noise for the commonly used satellite images, complicating the retrieval of
accurate glacier velocity. Assessments of velocity changes on short timescales and over complex areas such as mountain ranges are therefore still
lacking but are essential to better understand how glacier dynamics are
driven by internal and external factors. In this study, we take advantage of
the wide availability and redundancy of satellite imagery over the western
Pamirs to retrieve glacier velocity changes over 10 d intervals for 7 years
and for a wide range of glacier geometry and dynamics. Our results reveal
strong seasonal trends. In spring/summer, we observe velocity increases of
up to 300 % compared to a slow winter period. These accelerations clearly
migrate upglacier throughout the melt season, which we link to changes in
subglacial hydrology efficiency. In autumn, we observe glacier accelerations
that have rarely been observed before. These episodes are primarily confined
to the upper ablation zone with a clear downglacier migration. We suggest
that they result from glacier instabilities caused by sudden subglacial
pressurization in response to (1) supraglacial pond drainage and/or (2) gradual closure of the hydrological system. Our 10 d resolved measurements
allow us to characterize the short-term response of glaciers to changing
meteorological and climatic conditions.</p> |
| first_indexed | 2024-04-09T18:33:39Z |
| format | Article |
| id | doaj.art-002f7cbb81c447308375765080b4c0f3 |
| institution | Directory Open Access Journal |
| issn | 1994-0416 1994-0424 |
| language | English |
| last_indexed | 2024-04-09T18:33:39Z |
| publishDate | 2023-04-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | The Cryosphere |
| spelling | doaj.art-002f7cbb81c447308375765080b4c0f32023-04-11T12:26:07ZengCopernicus PublicationsThe Cryosphere1994-04161994-04242023-04-01171567158310.5194/tc-17-1567-2023Climatic control on seasonal variations in mountain glacier surface velocityU. Nanni0U. Nanni1D. Scherler2D. Scherler3F. Ayoub4R. Millan5F. Herman6J.-P. Avouac7Division of Geological and Planetary Science, California Institute of Technology, Pasadena, CA, USAnow at: Department of Geosciences, University of Oslo, Oslo, NorwayEarth Surface Geochemistry, GFZ German Research Centre for Geosciences, Potsdam, GermanyInstitute of Geographical Sciences, Freie Universität Berlin, Berlin, GermanyJet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USAUniversity of Grenoble Alpes, CNRS, IRD, IGE, Grenoble, FranceInstitute of Earth Surface Dynamics, University of Lausanne, 1015 Lausanne, SwitzerlandDivision of Geological and Planetary Science, California Institute of Technology, Pasadena, CA, USA<p>Accurate measurements of ice flow are essential to predict future changes in glaciers and ice caps. Glacier displacement can in principle be measured on the large scale by cross-correlation of satellite images. At weekly to monthly scales, the expected displacement is often of the same order as the noise for the commonly used satellite images, complicating the retrieval of accurate glacier velocity. Assessments of velocity changes on short timescales and over complex areas such as mountain ranges are therefore still lacking but are essential to better understand how glacier dynamics are driven by internal and external factors. In this study, we take advantage of the wide availability and redundancy of satellite imagery over the western Pamirs to retrieve glacier velocity changes over 10 d intervals for 7 years and for a wide range of glacier geometry and dynamics. Our results reveal strong seasonal trends. In spring/summer, we observe velocity increases of up to 300 % compared to a slow winter period. These accelerations clearly migrate upglacier throughout the melt season, which we link to changes in subglacial hydrology efficiency. In autumn, we observe glacier accelerations that have rarely been observed before. These episodes are primarily confined to the upper ablation zone with a clear downglacier migration. We suggest that they result from glacier instabilities caused by sudden subglacial pressurization in response to (1) supraglacial pond drainage and/or (2) gradual closure of the hydrological system. Our 10 d resolved measurements allow us to characterize the short-term response of glaciers to changing meteorological and climatic conditions.</p>https://tc.copernicus.org/articles/17/1567/2023/tc-17-1567-2023.pdf |
| spellingShingle | U. Nanni U. Nanni D. Scherler D. Scherler F. Ayoub R. Millan F. Herman J.-P. Avouac Climatic control on seasonal variations in mountain glacier surface velocity The Cryosphere |
| title | Climatic control on seasonal variations in mountain glacier surface velocity |
| title_full | Climatic control on seasonal variations in mountain glacier surface velocity |
| title_fullStr | Climatic control on seasonal variations in mountain glacier surface velocity |
| title_full_unstemmed | Climatic control on seasonal variations in mountain glacier surface velocity |
| title_short | Climatic control on seasonal variations in mountain glacier surface velocity |
| title_sort | climatic control on seasonal variations in mountain glacier surface velocity |
| url | https://tc.copernicus.org/articles/17/1567/2023/tc-17-1567-2023.pdf |
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