Effect of horizontal divergence on estimates of firn-air content
Abstract Ice-sheet mass-balance estimates derived from repeat satellite-altimetry observations require accurate calculation of spatiotemporal variability in firn-air content (FAC). However, firn-compaction models remain a large source of uncertainty within mass-balance estimates. In this study, we i...
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crcambridgeupr:10.1017/jog.2020.105 2024-06-23T07:53:49+00:00 Effect of horizontal divergence on estimates of firn-air content Horlings, Annika N. Christianson, Knut Holschuh, Nicholas Stevens, C. Max Waddington, Edwin D. 2020 http://dx.doi.org/10.1017/jog.2020.105 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143020001057 en eng Cambridge University Press (CUP) http://creativecommons.org/licenses/by/4.0/ Journal of Glaciology volume 67, issue 262, page 287-296 ISSN 0022-1430 1727-5652 journal-article 2020 crcambridgeupr https://doi.org/10.1017/jog.2020.105 2024-05-29T08:10:04Z Abstract Ice-sheet mass-balance estimates derived from repeat satellite-altimetry observations require accurate calculation of spatiotemporal variability in firn-air content (FAC). However, firn-compaction models remain a large source of uncertainty within mass-balance estimates. In this study, we investigate one process that is neglected in FAC estimates derived from firn-compaction models: enhanced layer thinning due to horizontal divergence. We incorporate a layer-thinning scheme into the Community Firn Model. At every time step, firn layers first densify according to a firn-compaction model and then thin further due to an imposed horizontal divergence rate without additional density changes. We find that horizontal divergence on Thwaites (THW) and Pine Island Glaciers can reduce local FAC by up to 41% and 18%, respectively. We also assess the impact of temporal variability of horizontal divergence on FAC. We find a 15% decrease in FAC between 2007 and 2016 due to horizontal divergence at a location that is characteristic of lower THW. This decrease accounts for 16% of the observed surface lowering, whereas climate variability alone causes negligible changes in FAC at this location. Omitting transient horizontal divergence in estimates of FAC leads to an overestimation of ice loss via satellite-altimetry methods in regions of dynamic ice flow. Article in Journal/Newspaper Ice Sheet Journal of Glaciology Cambridge University Press Journal of Glaciology 67 262 287 296 |
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Open Polar |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
description |
Abstract Ice-sheet mass-balance estimates derived from repeat satellite-altimetry observations require accurate calculation of spatiotemporal variability in firn-air content (FAC). However, firn-compaction models remain a large source of uncertainty within mass-balance estimates. In this study, we investigate one process that is neglected in FAC estimates derived from firn-compaction models: enhanced layer thinning due to horizontal divergence. We incorporate a layer-thinning scheme into the Community Firn Model. At every time step, firn layers first densify according to a firn-compaction model and then thin further due to an imposed horizontal divergence rate without additional density changes. We find that horizontal divergence on Thwaites (THW) and Pine Island Glaciers can reduce local FAC by up to 41% and 18%, respectively. We also assess the impact of temporal variability of horizontal divergence on FAC. We find a 15% decrease in FAC between 2007 and 2016 due to horizontal divergence at a location that is characteristic of lower THW. This decrease accounts for 16% of the observed surface lowering, whereas climate variability alone causes negligible changes in FAC at this location. Omitting transient horizontal divergence in estimates of FAC leads to an overestimation of ice loss via satellite-altimetry methods in regions of dynamic ice flow. |
format |
Article in Journal/Newspaper |
author |
Horlings, Annika N. Christianson, Knut Holschuh, Nicholas Stevens, C. Max Waddington, Edwin D. |
spellingShingle |
Horlings, Annika N. Christianson, Knut Holschuh, Nicholas Stevens, C. Max Waddington, Edwin D. Effect of horizontal divergence on estimates of firn-air content |
author_facet |
Horlings, Annika N. Christianson, Knut Holschuh, Nicholas Stevens, C. Max Waddington, Edwin D. |
author_sort |
Horlings, Annika N. |
title |
Effect of horizontal divergence on estimates of firn-air content |
title_short |
Effect of horizontal divergence on estimates of firn-air content |
title_full |
Effect of horizontal divergence on estimates of firn-air content |
title_fullStr |
Effect of horizontal divergence on estimates of firn-air content |
title_full_unstemmed |
Effect of horizontal divergence on estimates of firn-air content |
title_sort |
effect of horizontal divergence on estimates of firn-air content |
publisher |
Cambridge University Press (CUP) |
publishDate |
2020 |
url |
http://dx.doi.org/10.1017/jog.2020.105 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143020001057 |
genre |
Ice Sheet Journal of Glaciology |
genre_facet |
Ice Sheet Journal of Glaciology |
op_source |
Journal of Glaciology volume 67, issue 262, page 287-296 ISSN 0022-1430 1727-5652 |
op_rights |
http://creativecommons.org/licenses/by/4.0/ |
op_doi |
https://doi.org/10.1017/jog.2020.105 |
container_title |
Journal of Glaciology |
container_volume |
67 |
container_issue |
262 |
container_start_page |
287 |
op_container_end_page |
296 |
_version_ |
1802645645069123584 |