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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Published in:The Cryosphere
Main Authors: McDowell, Ian E., Keegan, Kaitlin M., Skiles, S. McKenzie, Donahue, Christopher P., Osterberg, Erich C., Hawley, Robert L., Marshall, Hans-Peter
Format: Article in Journal/Newspaper
Language:English
Published: Copernicus Publications 2024
Subjects:
Online Access:https://doi.org/10.5194/tc-18-1925-2024
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spelling 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
institution Open Polar
collection Niedersächsisches Online-Archiv NOA
op_collection_id ftnonlinearchiv
language English
topic article
Verlagsveröffentlichung
spellingShingle 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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