Present and future variations in Antarctic firn air content
A firn densification model (FDM) is used to assess spatial and temporal (1979–2200) variations in the depth, density and temperature of the firn layer covering the Antarctic ice sheet (AIS). A time-dependent version of the FDM is compared to more commonly used steady-state FDM results. Although the...
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ftdoajarticles:oai:doaj.org/article:af7bc90534324038b0defa6e4028114a 2023-05-15T13:46:45+02:00 Present and future variations in Antarctic firn air content S. R. M. Ligtenberg P. Kuipers Munneke M. R. van den Broeke 2014-09-01T00:00:00Z https://doi.org/10.5194/tc-8-1711-2014 https://doaj.org/article/af7bc90534324038b0defa6e4028114a EN eng Copernicus Publications http://www.the-cryosphere.net/8/1711/2014/tc-8-1711-2014.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-8-1711-2014 https://doaj.org/article/af7bc90534324038b0defa6e4028114a The Cryosphere, Vol 8, Iss 5, Pp 1711-1723 (2014) Environmental sciences GE1-350 Geology QE1-996.5 article 2014 ftdoajarticles https://doi.org/10.5194/tc-8-1711-2014 2022-12-31T05:15:27Z A firn densification model (FDM) is used to assess spatial and temporal (1979–2200) variations in the depth, density and temperature of the firn layer covering the Antarctic ice sheet (AIS). A time-dependent version of the FDM is compared to more commonly used steady-state FDM results. Although the average AIS firn air content (FAC) of both models is similar (22.5 m), large spatial differences are found: in the ice-sheet interior, the steady-state model underestimates the FAC by up to 2 m, while the FAC is overestimated by 5–15 m along the ice-sheet margins, due to significant surface melt. Applying the steady-state FAC values to convert surface elevation to ice thickness (i.e., assuming flotation at the grounding line) potentially results in an underestimation of ice discharge at the grounding line, and hence an underestimation of current AIS mass loss by 23.5% (or 16.7 Gt yr −1 ) with regard to the reconciled estimate over the period 1992–2011. The timing of the measurement is also important, as temporal FAC variations of 1–2 m are simulated within the 33 yr period (1979–2012). Until 2200, the Antarctic FAC is projected to change due to a combination of increasing accumulation, temperature, and surface melt. The latter two result in a decrease of FAC, due to (i) more refrozen meltwater, (ii) a higher densification rate, and (iii) a faster firn-to-ice transition at the bottom of the firn layer. These effects are, however, more than compensated for by increasing snowfall, leading to a 4–14% increase in FAC. Only in melt-affected regions, future FAC is simulated to decrease, with the largest changes (−50 to −80%) on the ice shelves in the Antarctic Peninsula and Dronning Maud Land. Integrated over the AIS, the increase in precipitation results in a similar volume increase due to ice and air (both ~150 km 3 yr −1 until 2100). Combined, this volume increase is equivalent to a surface elevation change of +2.1 cm yr −1 , which shows that variations in firn depth remain important to consider in future mass balance ... Article in Journal/Newspaper Antarc* Antarctic Antarctic Peninsula Dronning Maud Land Ice Sheet Ice Shelves The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic The Antarctic Antarctic Peninsula Dronning Maud Land The Cryosphere 8 5 1711 1723 |
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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 S. R. M. Ligtenberg P. Kuipers Munneke M. R. van den Broeke Present and future variations in Antarctic firn air content |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
A firn densification model (FDM) is used to assess spatial and temporal (1979–2200) variations in the depth, density and temperature of the firn layer covering the Antarctic ice sheet (AIS). A time-dependent version of the FDM is compared to more commonly used steady-state FDM results. Although the average AIS firn air content (FAC) of both models is similar (22.5 m), large spatial differences are found: in the ice-sheet interior, the steady-state model underestimates the FAC by up to 2 m, while the FAC is overestimated by 5–15 m along the ice-sheet margins, due to significant surface melt. Applying the steady-state FAC values to convert surface elevation to ice thickness (i.e., assuming flotation at the grounding line) potentially results in an underestimation of ice discharge at the grounding line, and hence an underestimation of current AIS mass loss by 23.5% (or 16.7 Gt yr −1 ) with regard to the reconciled estimate over the period 1992–2011. The timing of the measurement is also important, as temporal FAC variations of 1–2 m are simulated within the 33 yr period (1979–2012). Until 2200, the Antarctic FAC is projected to change due to a combination of increasing accumulation, temperature, and surface melt. The latter two result in a decrease of FAC, due to (i) more refrozen meltwater, (ii) a higher densification rate, and (iii) a faster firn-to-ice transition at the bottom of the firn layer. These effects are, however, more than compensated for by increasing snowfall, leading to a 4–14% increase in FAC. Only in melt-affected regions, future FAC is simulated to decrease, with the largest changes (−50 to −80%) on the ice shelves in the Antarctic Peninsula and Dronning Maud Land. Integrated over the AIS, the increase in precipitation results in a similar volume increase due to ice and air (both ~150 km 3 yr −1 until 2100). Combined, this volume increase is equivalent to a surface elevation change of +2.1 cm yr −1 , which shows that variations in firn depth remain important to consider in future mass balance ... |
format |
Article in Journal/Newspaper |
author |
S. R. M. Ligtenberg P. Kuipers Munneke M. R. van den Broeke |
author_facet |
S. R. M. Ligtenberg P. Kuipers Munneke M. R. van den Broeke |
author_sort |
S. R. M. Ligtenberg |
title |
Present and future variations in Antarctic firn air content |
title_short |
Present and future variations in Antarctic firn air content |
title_full |
Present and future variations in Antarctic firn air content |
title_fullStr |
Present and future variations in Antarctic firn air content |
title_full_unstemmed |
Present and future variations in Antarctic firn air content |
title_sort |
present and future variations in antarctic firn air content |
publisher |
Copernicus Publications |
publishDate |
2014 |
url |
https://doi.org/10.5194/tc-8-1711-2014 https://doaj.org/article/af7bc90534324038b0defa6e4028114a |
geographic |
Antarctic The Antarctic Antarctic Peninsula Dronning Maud Land |
geographic_facet |
Antarctic The Antarctic Antarctic Peninsula Dronning Maud Land |
genre |
Antarc* Antarctic Antarctic Peninsula Dronning Maud Land Ice Sheet Ice Shelves The Cryosphere |
genre_facet |
Antarc* Antarctic Antarctic Peninsula Dronning Maud Land Ice Sheet Ice Shelves The Cryosphere |
op_source |
The Cryosphere, Vol 8, Iss 5, Pp 1711-1723 (2014) |
op_relation |
http://www.the-cryosphere.net/8/1711/2014/tc-8-1711-2014.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 1994-0416 1994-0424 doi:10.5194/tc-8-1711-2014 https://doaj.org/article/af7bc90534324038b0defa6e4028114a |
op_doi |
https://doi.org/10.5194/tc-8-1711-2014 |
container_title |
The Cryosphere |
container_volume |
8 |
container_issue |
5 |
container_start_page |
1711 |
op_container_end_page |
1723 |
_version_ |
1766245170330730496 |