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 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 ea...
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2024
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00073228 2024-05-19T07:32:13+00:00 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 2024-04 electronic https://doi.org/10.5194/tc-18-1925-2024 https://noa.gwlb.de/receive/cop_mods_00073228 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00071408/tc-18-1925-2024.pdf https://tc.copernicus.org/articles/18/1925/2024/tc-18-1925-2024.pdf eng eng Copernicus Publications The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-18-1925-2024 https://noa.gwlb.de/receive/cop_mods_00073228 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00071408/tc-18-1925-2024.pdf https://tc.copernicus.org/articles/18/1925/2024/tc-18-1925-2024.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess article Verlagsveröffentlichung article Text doc-type:article 2024 ftnonlinearchiv https://doi.org/10.5194/tc-18-1925-2024 2024-04-29T23:46:10Z The Greenland and Antarctic ice sheets are covered in a 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 microstructural 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 test 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, is time-consuming, and can be subjective depending on the method. 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 effective grain size, a measure of NIR light absorption by firn grains, and NIR reflectance to produce high-resolution (0.4 mm) maps of effective 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 1.5× larger on average, which is largely related to the differences in measurement techniques. To demonstrate the utility of the firn stratigraphic maps produced by the NIR-HSI, we track the 2012 melt event across the ... Article in Journal/Newspaper Antarc* Antarctic Greenland ice core Ice Sheet The Cryosphere Niedersächsisches Online-Archiv NOA The Cryosphere 18 4 1925 1946 |
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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 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 microstructural 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 test 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, is time-consuming, and can be subjective depending on the method. 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 effective grain size, a measure of NIR light absorption by firn grains, and NIR reflectance to produce high-resolution (0.4 mm) maps of effective 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 1.5× larger on average, which is largely related to the differences in measurement techniques. To demonstrate the utility of the firn stratigraphic maps produced by the NIR-HSI, we track the 2012 melt event across the ... |
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 |
2024 |
url |
https://doi.org/10.5194/tc-18-1925-2024 https://noa.gwlb.de/receive/cop_mods_00073228 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00071408/tc-18-1925-2024.pdf https://tc.copernicus.org/articles/18/1925/2024/tc-18-1925-2024.pdf |
genre |
Antarc* Antarctic Greenland ice core Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctic Greenland ice core Ice Sheet The Cryosphere |
op_relation |
The Cryosphere -- ˜Theœ Cryosphere -- http://www.bibliothek.uni-regensburg.de/ezeit/?2393169 -- http://www.the-cryosphere.net/ -- 1994-0424 https://doi.org/10.5194/tc-18-1925-2024 https://noa.gwlb.de/receive/cop_mods_00073228 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00071408/tc-18-1925-2024.pdf https://tc.copernicus.org/articles/18/1925/2024/tc-18-1925-2024.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_doi |
https://doi.org/10.5194/tc-18-1925-2024 |
container_title |
The Cryosphere |
container_volume |
18 |
container_issue |
4 |
container_start_page |
1925 |
op_container_end_page |
1946 |
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1799470205421748224 |