Development of physically based liquid water schemes for Greenland firn-densification models
As surface melt is increasing on the Greenland Ice Sheet (GrIS), quantifying the retention capacity of the firn layer is critical to linking meltwater production to meltwater runoff. Firn-densification models have so far relied on empirical approaches to account for the percolation–refreezing proces...
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Copernicus Publications
2019
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00001464 2023-05-15T16:28:58+02:00 Development of physically based liquid water schemes for Greenland firn-densification models Verjans, Vincent Leeson, Amber A. Stevens, C. Max MacFerrin, Michael Noël, Brice van den Broeke, Michiel R. 2019-07 electronic https://doi.org/10.5194/tc-13-1819-2019 https://noa.gwlb.de/receive/cop_mods_00001464 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00001425/tc-13-1819-2019.pdf https://tc.copernicus.org/articles/13/1819/2019/tc-13-1819-2019.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-13-1819-2019 https://noa.gwlb.de/receive/cop_mods_00001464 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00001425/tc-13-1819-2019.pdf https://tc.copernicus.org/articles/13/1819/2019/tc-13-1819-2019.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2019 ftnonlinearchiv https://doi.org/10.5194/tc-13-1819-2019 2022-02-08T23:01:51Z As surface melt is increasing on the Greenland Ice Sheet (GrIS), quantifying the retention capacity of the firn layer is critical to linking meltwater production to meltwater runoff. Firn-densification models have so far relied on empirical approaches to account for the percolation–refreezing process, and more physically based representations of liquid water flow might bring improvements to model performance. Here we implement three types of water percolation schemes into the Community Firn Model: the bucket approach, the Richards equation in a single domain and the Richards equation in a dual domain, which accounts for partitioning between matrix and fast preferential flow. We investigate their impact on firn densification at four locations on the GrIS and compare model results with observations. We find that for all of the flow schemes, significant discrepancies remain with respect to observed firn density, particularly the density variability in depth, and that inter-model differences are large (porosity of the upper 15 m firn varies by up to 47 %). The simple bucket scheme is as efficient in replicating observed density profiles as the single-domain Richards equation, and the most physically detailed dual-domain scheme does not necessarily reach best agreement with observed data. However, we find that the implementation of preferential flow simulates ice-layer formation more reliably and allows for deeper percolation. We also find that the firn model is more sensitive to the choice of densification scheme than to the choice of water percolation scheme. The disagreements with observations and the spread in model results demonstrate that progress towards an accurate description of water flow in firn is necessary. The numerous uncertainties about firn structure (e.g. grain size and shape, presence of ice layers) and about its hydraulic properties, as well as the one-dimensionality of firn models, render the implementation of physically based percolation schemes difficult. Additionally, the performance of firn models is still affected by the various effects affecting the densification process such as microstructural effects, wet snow metamorphism and temperature sensitivity when meltwater is present. Article in Journal/Newspaper Greenland Ice Sheet The Cryosphere Niedersächsisches Online-Archiv NOA Greenland The Cryosphere 13 7 1819 1842 |
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Niedersächsisches Online-Archiv NOA |
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English |
topic |
article Verlagsveröffentlichung |
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article Verlagsveröffentlichung Verjans, Vincent Leeson, Amber A. Stevens, C. Max MacFerrin, Michael Noël, Brice van den Broeke, Michiel R. Development of physically based liquid water schemes for Greenland firn-densification models |
topic_facet |
article Verlagsveröffentlichung |
description |
As surface melt is increasing on the Greenland Ice Sheet (GrIS), quantifying the retention capacity of the firn layer is critical to linking meltwater production to meltwater runoff. Firn-densification models have so far relied on empirical approaches to account for the percolation–refreezing process, and more physically based representations of liquid water flow might bring improvements to model performance. Here we implement three types of water percolation schemes into the Community Firn Model: the bucket approach, the Richards equation in a single domain and the Richards equation in a dual domain, which accounts for partitioning between matrix and fast preferential flow. We investigate their impact on firn densification at four locations on the GrIS and compare model results with observations. We find that for all of the flow schemes, significant discrepancies remain with respect to observed firn density, particularly the density variability in depth, and that inter-model differences are large (porosity of the upper 15 m firn varies by up to 47 %). The simple bucket scheme is as efficient in replicating observed density profiles as the single-domain Richards equation, and the most physically detailed dual-domain scheme does not necessarily reach best agreement with observed data. However, we find that the implementation of preferential flow simulates ice-layer formation more reliably and allows for deeper percolation. We also find that the firn model is more sensitive to the choice of densification scheme than to the choice of water percolation scheme. The disagreements with observations and the spread in model results demonstrate that progress towards an accurate description of water flow in firn is necessary. The numerous uncertainties about firn structure (e.g. grain size and shape, presence of ice layers) and about its hydraulic properties, as well as the one-dimensionality of firn models, render the implementation of physically based percolation schemes difficult. Additionally, the performance of firn models is still affected by the various effects affecting the densification process such as microstructural effects, wet snow metamorphism and temperature sensitivity when meltwater is present. |
format |
Article in Journal/Newspaper |
author |
Verjans, Vincent Leeson, Amber A. Stevens, C. Max MacFerrin, Michael Noël, Brice van den Broeke, Michiel R. |
author_facet |
Verjans, Vincent Leeson, Amber A. Stevens, C. Max MacFerrin, Michael Noël, Brice van den Broeke, Michiel R. |
author_sort |
Verjans, Vincent |
title |
Development of physically based liquid water schemes for Greenland firn-densification models |
title_short |
Development of physically based liquid water schemes for Greenland firn-densification models |
title_full |
Development of physically based liquid water schemes for Greenland firn-densification models |
title_fullStr |
Development of physically based liquid water schemes for Greenland firn-densification models |
title_full_unstemmed |
Development of physically based liquid water schemes for Greenland firn-densification models |
title_sort |
development of physically based liquid water schemes for greenland firn-densification models |
publisher |
Copernicus Publications |
publishDate |
2019 |
url |
https://doi.org/10.5194/tc-13-1819-2019 https://noa.gwlb.de/receive/cop_mods_00001464 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00001425/tc-13-1819-2019.pdf https://tc.copernicus.org/articles/13/1819/2019/tc-13-1819-2019.pdf |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
Greenland Ice Sheet The Cryosphere |
genre_facet |
Greenland 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-13-1819-2019 https://noa.gwlb.de/receive/cop_mods_00001464 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00001425/tc-13-1819-2019.pdf https://tc.copernicus.org/articles/13/1819/2019/tc-13-1819-2019.pdf |
op_rights |
https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess |
op_rightsnorm |
CC-BY |
op_doi |
https://doi.org/10.5194/tc-13-1819-2019 |
container_title |
The Cryosphere |
container_volume |
13 |
container_issue |
7 |
container_start_page |
1819 |
op_container_end_page |
1842 |
_version_ |
1766018647369711616 |