On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet
It is highly uncertain how the humidity flux between the snow surface and the atmosphere contributes to the surface mass balance (SMB) of the interior Greenland Ice Sheet (GrIS). Due to sparse observations, evaluations of the simulated humidity flux are limited. Model-based estimates of the humidity...
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2024
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ftdoajarticles:oai:doaj.org/article:c17779de19b2404395790cd5bcbee158 2024-02-11T10:03:28+01:00 On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet L. J. Dietrich H. C. Steen-Larsen S. Wahl A.-K. Faber X. Fettweis 2024-01-01T00:00:00Z https://doi.org/10.5194/tc-18-289-2024 https://doaj.org/article/c17779de19b2404395790cd5bcbee158 EN eng Copernicus Publications https://tc.copernicus.org/articles/18/289/2024/tc-18-289-2024.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-18-289-2024 1994-0416 1994-0424 https://doaj.org/article/c17779de19b2404395790cd5bcbee158 The Cryosphere, Vol 18, Pp 289-305 (2024) Environmental sciences GE1-350 Geology QE1-996.5 article 2024 ftdoajarticles https://doi.org/10.5194/tc-18-289-2024 2024-01-21T01:41:59Z It is highly uncertain how the humidity flux between the snow surface and the atmosphere contributes to the surface mass balance (SMB) of the interior Greenland Ice Sheet (GrIS). Due to sparse observations, evaluations of the simulated humidity flux are limited. Model-based estimates of the humidity flux contribution to the SMB are, therefore, unconstrained and even disagree in magnitude and sign. In this study, we evaluate the regional climate model MAR at the EGRIP (East Greenland Ice-Core Project) site in the accumulation zone of the GrIS. We use a combined dataset of continuous one-level bulk estimates of the humidity flux covering the period of May 2016–August 2019 and eddy-resolving eddy-covariance humidity flux measurements from all four summer seasons. In summer, we document a bias of too little sublimation ( − 1.3 W m −2 , − 1.65 mm w.e.) caused by a cold bias in both air and surface temperature, leading to a reduced humidity gradient. In winter, MAR overestimates vapor deposition by about 1 order of magnitude. This is a consequence of an overestimated temperature gradient in too stable atmospheric conditions compared to observations. Both systematic errors cause a large discrepancy in the annual net humidity flux between the model and observations of − 9 mm w.e. yr −1 . Remarkably, the simulated net annual humidity flux contributes positively to the SMB, contrary to observations documenting a net sublimation flux. We correct the systematic errors by applying a simple but effective correction function to the simulated latent heat flux. Using this correction, we find that 5.1 % of the annual mass gain at the EGRIP site sublimates again, and 4.3 % of the total mass gain is deposited vapor from the near-surface air. The estimated net humidity flux contribution to the annual SMB is about − 1 % (net sublimation) compared to + 5.6 % for the uncorrected simulation. In summer, the corrected MAR simulation shows that vapor deposition accounts for 9.6 % of the total mass gain and that 31 % of the total mass gain ... Article in Journal/Newspaper East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project ice core Ice Sheet The Cryosphere Directory of Open Access Journals: DOAJ Articles Greenland The Cryosphere 18 1 289 305 |
institution |
Open Polar |
collection |
Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 L. J. Dietrich H. C. Steen-Larsen S. Wahl A.-K. Faber X. Fettweis On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
It is highly uncertain how the humidity flux between the snow surface and the atmosphere contributes to the surface mass balance (SMB) of the interior Greenland Ice Sheet (GrIS). Due to sparse observations, evaluations of the simulated humidity flux are limited. Model-based estimates of the humidity flux contribution to the SMB are, therefore, unconstrained and even disagree in magnitude and sign. In this study, we evaluate the regional climate model MAR at the EGRIP (East Greenland Ice-Core Project) site in the accumulation zone of the GrIS. We use a combined dataset of continuous one-level bulk estimates of the humidity flux covering the period of May 2016–August 2019 and eddy-resolving eddy-covariance humidity flux measurements from all four summer seasons. In summer, we document a bias of too little sublimation ( − 1.3 W m −2 , − 1.65 mm w.e.) caused by a cold bias in both air and surface temperature, leading to a reduced humidity gradient. In winter, MAR overestimates vapor deposition by about 1 order of magnitude. This is a consequence of an overestimated temperature gradient in too stable atmospheric conditions compared to observations. Both systematic errors cause a large discrepancy in the annual net humidity flux between the model and observations of − 9 mm w.e. yr −1 . Remarkably, the simulated net annual humidity flux contributes positively to the SMB, contrary to observations documenting a net sublimation flux. We correct the systematic errors by applying a simple but effective correction function to the simulated latent heat flux. Using this correction, we find that 5.1 % of the annual mass gain at the EGRIP site sublimates again, and 4.3 % of the total mass gain is deposited vapor from the near-surface air. The estimated net humidity flux contribution to the annual SMB is about − 1 % (net sublimation) compared to + 5.6 % for the uncorrected simulation. In summer, the corrected MAR simulation shows that vapor deposition accounts for 9.6 % of the total mass gain and that 31 % of the total mass gain ... |
format |
Article in Journal/Newspaper |
author |
L. J. Dietrich H. C. Steen-Larsen S. Wahl A.-K. Faber X. Fettweis |
author_facet |
L. J. Dietrich H. C. Steen-Larsen S. Wahl A.-K. Faber X. Fettweis |
author_sort |
L. J. Dietrich |
title |
On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet |
title_short |
On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet |
title_full |
On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet |
title_fullStr |
On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet |
title_full_unstemmed |
On the importance of the humidity flux for the surface mass balance in the accumulation zone of the Greenland Ice Sheet |
title_sort |
on the importance of the humidity flux for the surface mass balance in the accumulation zone of the greenland ice sheet |
publisher |
Copernicus Publications |
publishDate |
2024 |
url |
https://doi.org/10.5194/tc-18-289-2024 https://doaj.org/article/c17779de19b2404395790cd5bcbee158 |
geographic |
Greenland |
geographic_facet |
Greenland |
genre |
East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project ice core Ice Sheet The Cryosphere |
genre_facet |
East Greenland East Greenland Ice-core Project Greenland Greenland ice core Greenland Ice core Project ice core Ice Sheet The Cryosphere |
op_source |
The Cryosphere, Vol 18, Pp 289-305 (2024) |
op_relation |
https://tc.copernicus.org/articles/18/289/2024/tc-18-289-2024.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-18-289-2024 1994-0416 1994-0424 https://doaj.org/article/c17779de19b2404395790cd5bcbee158 |
op_doi |
https://doi.org/10.5194/tc-18-289-2024 |
container_title |
The Cryosphere |
container_volume |
18 |
container_issue |
1 |
container_start_page |
289 |
op_container_end_page |
305 |
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1790599700723793920 |