A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores
The Greenland and Antarctic ice sheets are covered in a thick layer of porous firn. Knowledge of firn structure improves our understanding of ice sheet mass balance, supra- and englacial hydrology, and ice core paleoclimate records. While macroscale firn properties, such as firn density, are relativ...
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Copernicus Publications
2023
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00069623 2023-12-03T10:11:18+01:00 A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores McDowell, Ian E. Keegan, Kaitlin M. Skiles, S. McKenzie Donahue, Christopher P. Osterberg, Erich C. Hawley, Robert L. Marshall, Hans-Peter 2023-11 electronic https://doi.org/10.5194/egusphere-2023-2351 https://noa.gwlb.de/receive/cop_mods_00069623 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068001/egusphere-2023-2351.pdf https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2351/egusphere-2023-2351.pdf eng eng Copernicus Publications https://doi.org/10.5194/egusphere-2023-2351 https://noa.gwlb.de/receive/cop_mods_00069623 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068001/egusphere-2023-2351.pdf https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2351/egusphere-2023-2351.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2023 ftnonlinearchiv https://doi.org/10.5194/egusphere-2023-2351 2023-11-06T00:22:50Z The Greenland and Antarctic ice sheets are covered in a thick layer of porous firn. Knowledge of firn structure improves our understanding of ice sheet mass balance, supra- and englacial hydrology, and ice core paleoclimate records. While macroscale firn properties, such as firn density, are relatively easy to measure in the field or lab, more intensive measurements of grain-scale properties are necessary to reduce uncertainty in remote sensing observations of mass balance, model meltwater infiltration, and constrain ice age – gas age differences in ice cores. Additionally, as the duration and extent of surface melting increases, refreezing meltwater will greatly alter firn structure. Field observations of firn grain size and ice layer stratigraphy are required to inform and validate physical models that simulate the ice sheet-wide evolution of the firn layer. However, visually measuring grain size and ice layer distributions is tedious, time-consuming, and subjective. Here we demonstrate a method to systematically map firn core grain size and ice layer stratigraphy using a near-infrared hyperspectral imager (NIR-HSI; 900–1700 nm). We scanned 14 firn cores spanning ∼1000 km across western Greenland’s percolation zone with the NIR-HSI mounted on a linear translation stage in a cold laboratory. We leverage the relationship between ice grain size and near-infrared absorption to retrieve effective grain radii by inverting measured reflectance to produce high-resolution (0.4 mm) maps of grain size and ice layer stratigraphy. We show the NIR-HSI reproduces visually-identified ice layer stratigraphy and infiltration ice content across all cores. Effective grain sizes change synchronously with traditionally-measured grain radii with depth, although effective grains in each core are 1.5x larger on average, which can be explained by firn grain geometry. To demonstrate the utility of the firn stratigraphic maps produced by the NIR-HSI, we track the 2012 melt event across the transect and assess its impact on deep firn ... Article in Journal/Newspaper Antarc* Antarctic Greenland ice core Ice Sheet Niedersächsisches Online-Archiv NOA Antarctic Greenland |
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Niedersächsisches Online-Archiv NOA |
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ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung McDowell, Ian E. Keegan, Kaitlin M. Skiles, S. McKenzie Donahue, Christopher P. Osterberg, Erich C. Hawley, Robert L. Marshall, Hans-Peter A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
topic_facet |
article Verlagsveröffentlichung |
description |
The Greenland and Antarctic ice sheets are covered in a thick layer of porous firn. Knowledge of firn structure improves our understanding of ice sheet mass balance, supra- and englacial hydrology, and ice core paleoclimate records. While macroscale firn properties, such as firn density, are relatively easy to measure in the field or lab, more intensive measurements of grain-scale properties are necessary to reduce uncertainty in remote sensing observations of mass balance, model meltwater infiltration, and constrain ice age – gas age differences in ice cores. Additionally, as the duration and extent of surface melting increases, refreezing meltwater will greatly alter firn structure. Field observations of firn grain size and ice layer stratigraphy are required to inform and validate physical models that simulate the ice sheet-wide evolution of the firn layer. However, visually measuring grain size and ice layer distributions is tedious, time-consuming, and subjective. Here we demonstrate a method to systematically map firn core grain size and ice layer stratigraphy using a near-infrared hyperspectral imager (NIR-HSI; 900–1700 nm). We scanned 14 firn cores spanning ∼1000 km across western Greenland’s percolation zone with the NIR-HSI mounted on a linear translation stage in a cold laboratory. We leverage the relationship between ice grain size and near-infrared absorption to retrieve effective grain radii by inverting measured reflectance to produce high-resolution (0.4 mm) maps of grain size and ice layer stratigraphy. We show the NIR-HSI reproduces visually-identified ice layer stratigraphy and infiltration ice content across all cores. Effective grain sizes change synchronously with traditionally-measured grain radii with depth, although effective grains in each core are 1.5x larger on average, which can be explained by firn grain geometry. To demonstrate the utility of the firn stratigraphic maps produced by the NIR-HSI, we track the 2012 melt event across the transect and assess its impact on deep firn ... |
format |
Article in Journal/Newspaper |
author |
McDowell, Ian E. Keegan, Kaitlin M. Skiles, S. McKenzie Donahue, Christopher P. Osterberg, Erich C. Hawley, Robert L. Marshall, Hans-Peter |
author_facet |
McDowell, Ian E. Keegan, Kaitlin M. Skiles, S. McKenzie Donahue, Christopher P. Osterberg, Erich C. Hawley, Robert L. Marshall, Hans-Peter |
author_sort |
McDowell, Ian E. |
title |
A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
title_short |
A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
title_full |
A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
title_fullStr |
A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
title_full_unstemmed |
A cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
title_sort |
cold laboratory hyperspectral imaging system to map grain size and ice layer distributions in firn cores |
publisher |
Copernicus Publications |
publishDate |
2023 |
url |
https://doi.org/10.5194/egusphere-2023-2351 https://noa.gwlb.de/receive/cop_mods_00069623 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068001/egusphere-2023-2351.pdf https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2351/egusphere-2023-2351.pdf |
geographic |
Antarctic Greenland |
geographic_facet |
Antarctic Greenland |
genre |
Antarc* Antarctic Greenland ice core Ice Sheet |
genre_facet |
Antarc* Antarctic Greenland ice core Ice Sheet |
op_relation |
https://doi.org/10.5194/egusphere-2023-2351 https://noa.gwlb.de/receive/cop_mods_00069623 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00068001/egusphere-2023-2351.pdf https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2351/egusphere-2023-2351.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/egusphere-2023-2351 |
_version_ |
1784277096632156160 |