Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf
An extensive network of GPS sites on the Filchner–Ronne Ice Shelf and adjoining ice streams shows strong tidal modulation of horizontal ice flow at a range of frequencies. A particularly strong (horizontal) response is found at the fortnightly (Msf) frequency. Since this tidal constituent is absent...
Published in: | The Cryosphere |
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Language: | English |
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Copernicus Publications
2020
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ftnonlinearchiv:oai:noa.gwlb.de:cop_mods_00050009 2023-05-15T16:13:14+02:00 Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf Rosier, Sebastian H. R. Gudmundsson, G. Hilmar 2020-01 electronic https://doi.org/10.5194/tc-14-17-2020 https://noa.gwlb.de/receive/cop_mods_00050009 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00049626/tc-14-17-2020.pdf https://tc.copernicus.org/articles/14/17/2020/tc-14-17-2020.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-14-17-2020 https://noa.gwlb.de/receive/cop_mods_00050009 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00049626/tc-14-17-2020.pdf https://tc.copernicus.org/articles/14/17/2020/tc-14-17-2020.pdf https://creativecommons.org/licenses/by/4.0/ uneingeschränkt info:eu-repo/semantics/openAccess CC-BY article Verlagsveröffentlichung article Text doc-type:article 2020 ftnonlinearchiv https://doi.org/10.5194/tc-14-17-2020 2022-02-08T22:37:05Z An extensive network of GPS sites on the Filchner–Ronne Ice Shelf and adjoining ice streams shows strong tidal modulation of horizontal ice flow at a range of frequencies. A particularly strong (horizontal) response is found at the fortnightly (Msf) frequency. Since this tidal constituent is absent in the (vertical) tidal forcing, this observation implies the action of some non-linear mechanism. Another striking aspect is the strong amplitude of the flow perturbation, causing a periodic reversal in the direction of ice shelf flow in some areas and a 10 %–20 % change in speed at grounding lines. No model has yet been able to reproduce the quantitative aspects of the observed tidal modulation across the entire Filchner–Ronne Ice Shelf. The cause of the tidal ice flow response has, therefore, remained an enigma, indicating a serious limitation in our current understanding of the mechanics of large-scale ice flow. A further limitation of previous studies is that they have all focused on isolated regions and interactions between different areas have, therefore, not been fully accounted for. Here, we conduct the first large-scale ice flow modelling study to explore these processes using a viscoelastic rheology and realistic geometry of the entire Filchner–Ronne Ice Shelf, where the best observations of tidal response are available. We evaluate all relevant mechanisms that have hitherto been put forward to explain how tides might affect ice shelf flow and compare our results with observational data. We conclude that, while some are able to generate the correct general qualitative aspects of the tidally induced perturbations in ice flow, most of these mechanisms must be ruled out as being the primary cause of the observed long-period response. We find that only tidally induced lateral migration of grounding lines can generate a sufficiently strong long-period Msf response on the ice shelf to match observations. Furthermore, we show that the observed horizontal short-period semidiurnal tidal motion, causing twice-daily flow reversals at the ice front, can be generated through a purely elastic response to basin-wide tidal perturbations in the ice shelf slope. This model also allows us to quantify the effect of tides on mean ice flow and we find that the Filchner–Ronne Ice Shelf flows, on average, ∼ 21 % faster than it would in the absence of large ocean tides. Article in Journal/Newspaper Filchner Ronne Ice Shelf Filchner-Ronne Ice Shelf Ice Shelf Ronne Ice Shelf The Cryosphere Niedersächsisches Online-Archiv NOA Ronne Ice Shelf ENVELOPE(-61.000,-61.000,-78.500,-78.500) The Cryosphere 14 1 17 37 |
institution |
Open Polar |
collection |
Niedersächsisches Online-Archiv NOA |
op_collection_id |
ftnonlinearchiv |
language |
English |
topic |
article Verlagsveröffentlichung |
spellingShingle |
article Verlagsveröffentlichung Rosier, Sebastian H. R. Gudmundsson, G. Hilmar Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf |
topic_facet |
article Verlagsveröffentlichung |
description |
An extensive network of GPS sites on the Filchner–Ronne Ice Shelf and adjoining ice streams shows strong tidal modulation of horizontal ice flow at a range of frequencies. A particularly strong (horizontal) response is found at the fortnightly (Msf) frequency. Since this tidal constituent is absent in the (vertical) tidal forcing, this observation implies the action of some non-linear mechanism. Another striking aspect is the strong amplitude of the flow perturbation, causing a periodic reversal in the direction of ice shelf flow in some areas and a 10 %–20 % change in speed at grounding lines. No model has yet been able to reproduce the quantitative aspects of the observed tidal modulation across the entire Filchner–Ronne Ice Shelf. The cause of the tidal ice flow response has, therefore, remained an enigma, indicating a serious limitation in our current understanding of the mechanics of large-scale ice flow. A further limitation of previous studies is that they have all focused on isolated regions and interactions between different areas have, therefore, not been fully accounted for. Here, we conduct the first large-scale ice flow modelling study to explore these processes using a viscoelastic rheology and realistic geometry of the entire Filchner–Ronne Ice Shelf, where the best observations of tidal response are available. We evaluate all relevant mechanisms that have hitherto been put forward to explain how tides might affect ice shelf flow and compare our results with observational data. We conclude that, while some are able to generate the correct general qualitative aspects of the tidally induced perturbations in ice flow, most of these mechanisms must be ruled out as being the primary cause of the observed long-period response. We find that only tidally induced lateral migration of grounding lines can generate a sufficiently strong long-period Msf response on the ice shelf to match observations. Furthermore, we show that the observed horizontal short-period semidiurnal tidal motion, causing twice-daily flow reversals at the ice front, can be generated through a purely elastic response to basin-wide tidal perturbations in the ice shelf slope. This model also allows us to quantify the effect of tides on mean ice flow and we find that the Filchner–Ronne Ice Shelf flows, on average, ∼ 21 % faster than it would in the absence of large ocean tides. |
format |
Article in Journal/Newspaper |
author |
Rosier, Sebastian H. R. Gudmundsson, G. Hilmar |
author_facet |
Rosier, Sebastian H. R. Gudmundsson, G. Hilmar |
author_sort |
Rosier, Sebastian H. R. |
title |
Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf |
title_short |
Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf |
title_full |
Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf |
title_fullStr |
Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf |
title_full_unstemmed |
Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf |
title_sort |
exploring mechanisms responsible for tidal modulation in flow of the filchner–ronne ice shelf |
publisher |
Copernicus Publications |
publishDate |
2020 |
url |
https://doi.org/10.5194/tc-14-17-2020 https://noa.gwlb.de/receive/cop_mods_00050009 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00049626/tc-14-17-2020.pdf https://tc.copernicus.org/articles/14/17/2020/tc-14-17-2020.pdf |
long_lat |
ENVELOPE(-61.000,-61.000,-78.500,-78.500) |
geographic |
Ronne Ice Shelf |
geographic_facet |
Ronne Ice Shelf |
genre |
Filchner Ronne Ice Shelf Filchner-Ronne Ice Shelf Ice Shelf Ronne Ice Shelf The Cryosphere |
genre_facet |
Filchner Ronne Ice Shelf Filchner-Ronne Ice Shelf Ice Shelf Ronne Ice Shelf 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-14-17-2020 https://noa.gwlb.de/receive/cop_mods_00050009 https://noa.gwlb.de/servlets/MCRFileNodeServlet/cop_derivate_00049626/tc-14-17-2020.pdf https://tc.copernicus.org/articles/14/17/2020/tc-14-17-2020.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-14-17-2020 |
container_title |
The Cryosphere |
container_volume |
14 |
container_issue |
1 |
container_start_page |
17 |
op_container_end_page |
37 |
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1765998886529269760 |