Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021
Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding of the evolution of the combined ice and air content within the firn column. In the absence of suitable techniques to observe the changes to the firn column across the entirety of an ice sheet, the firn column...
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2022
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ftdoajarticles:oai:doaj.org/article:cf51ae82b1974a16b0a606e5b9d53658 2023-05-15T14:04:16+02:00 Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 B. Medley T. A. Neumann H. J. Zwally B. E. Smith C. M. Stevens 2022-10-01T00:00:00Z https://doi.org/10.5194/tc-16-3971-2022 https://doaj.org/article/cf51ae82b1974a16b0a606e5b9d53658 EN eng Copernicus Publications https://tc.copernicus.org/articles/16/3971/2022/tc-16-3971-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-3971-2022 1994-0416 1994-0424 https://doaj.org/article/cf51ae82b1974a16b0a606e5b9d53658 The Cryosphere, Vol 16, Pp 3971-4011 (2022) Environmental sciences GE1-350 Geology QE1-996.5 article 2022 ftdoajarticles https://doi.org/10.5194/tc-16-3971-2022 2022-12-30T20:53:21Z Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding of the evolution of the combined ice and air content within the firn column. In the absence of suitable techniques to observe the changes to the firn column across the entirety of an ice sheet, the firn column processes are typically modeled. Here, we present new simulations of firn processes over the Greenland and Antarctic ice sheets (GrIS and AIS) using the Community Firn Model and atmospheric reanalysis variables for more than four decades. A data set of more than 250 measured depth–density profiles from both ice sheets provides the basis of the calibration of the dry-snow densification scheme. The resulting scheme results in a reduction in the rate of densification, relative to a commonly used semi-empirical model, through a decreased dependence on the accumulation rate, a proxy for overburden stress. The 1980–2020 modeled firn column runoff, when combined with atmospheric variables from MERRA-2, generates realistic mean integrated surface mass balance values for the Greenland ( +390 Gt yr −1 ) and Antarctic ( +2612 Gt yr −1 ) ice sheets when compared to published model-ensemble means. We find that seasonal volume changes associated with firn air content are on average approximately 2.5 times larger than those associated with mass fluxes from surface processes for the AIS and 1.5 times larger for the GrIS; however, when averaged over multiple years, ice and air-volume fluctuations within the firn column are of comparable magnitudes. Between 1996 and 2019, the Greenland Ice Sheet lost nearly 5 % of its firn air content, indicating a reduction in the total meltwater retention capability. Nearly all (94 %) of the meltwater produced over the Antarctic Ice Sheet is retained within the firn column through infiltration and refreezing. Article in Journal/Newspaper Antarc* Antarctic Greenland Ice Sheet The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Greenland Merra ENVELOPE(12.615,12.615,65.816,65.816) The Cryosphere 16 10 3971 4011 |
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 B. Medley T. A. Neumann H. J. Zwally B. E. Smith C. M. Stevens Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
Conversion of altimetry-derived ice-sheet volume change to mass requires an understanding of the evolution of the combined ice and air content within the firn column. In the absence of suitable techniques to observe the changes to the firn column across the entirety of an ice sheet, the firn column processes are typically modeled. Here, we present new simulations of firn processes over the Greenland and Antarctic ice sheets (GrIS and AIS) using the Community Firn Model and atmospheric reanalysis variables for more than four decades. A data set of more than 250 measured depth–density profiles from both ice sheets provides the basis of the calibration of the dry-snow densification scheme. The resulting scheme results in a reduction in the rate of densification, relative to a commonly used semi-empirical model, through a decreased dependence on the accumulation rate, a proxy for overburden stress. The 1980–2020 modeled firn column runoff, when combined with atmospheric variables from MERRA-2, generates realistic mean integrated surface mass balance values for the Greenland ( +390 Gt yr −1 ) and Antarctic ( +2612 Gt yr −1 ) ice sheets when compared to published model-ensemble means. We find that seasonal volume changes associated with firn air content are on average approximately 2.5 times larger than those associated with mass fluxes from surface processes for the AIS and 1.5 times larger for the GrIS; however, when averaged over multiple years, ice and air-volume fluctuations within the firn column are of comparable magnitudes. Between 1996 and 2019, the Greenland Ice Sheet lost nearly 5 % of its firn air content, indicating a reduction in the total meltwater retention capability. Nearly all (94 %) of the meltwater produced over the Antarctic Ice Sheet is retained within the firn column through infiltration and refreezing. |
format |
Article in Journal/Newspaper |
author |
B. Medley T. A. Neumann H. J. Zwally B. E. Smith C. M. Stevens |
author_facet |
B. Medley T. A. Neumann H. J. Zwally B. E. Smith C. M. Stevens |
author_sort |
B. Medley |
title |
Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 |
title_short |
Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 |
title_full |
Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 |
title_fullStr |
Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 |
title_full_unstemmed |
Simulations of firn processes over the Greenland and Antarctic ice sheets: 1980–2021 |
title_sort |
simulations of firn processes over the greenland and antarctic ice sheets: 1980–2021 |
publisher |
Copernicus Publications |
publishDate |
2022 |
url |
https://doi.org/10.5194/tc-16-3971-2022 https://doaj.org/article/cf51ae82b1974a16b0a606e5b9d53658 |
long_lat |
ENVELOPE(12.615,12.615,65.816,65.816) |
geographic |
Antarctic The Antarctic Greenland Merra |
geographic_facet |
Antarctic The Antarctic Greenland Merra |
genre |
Antarc* Antarctic Greenland Ice Sheet The Cryosphere |
genre_facet |
Antarc* Antarctic Greenland Ice Sheet The Cryosphere |
op_source |
The Cryosphere, Vol 16, Pp 3971-4011 (2022) |
op_relation |
https://tc.copernicus.org/articles/16/3971/2022/tc-16-3971-2022.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-16-3971-2022 1994-0416 1994-0424 https://doaj.org/article/cf51ae82b1974a16b0a606e5b9d53658 |
op_doi |
https://doi.org/10.5194/tc-16-3971-2022 |
container_title |
The Cryosphere |
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16 |
container_issue |
10 |
container_start_page |
3971 |
op_container_end_page |
4011 |
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