author_facet Rosier, Sebastian H. R.
Gudmundsson, G. Hilmar
Rosier, Sebastian H. R.
Gudmundsson, G. Hilmar
author Rosier, Sebastian H. R.
Gudmundsson, G. Hilmar
spellingShingle Rosier, Sebastian H. R.
Gudmundsson, G. Hilmar
The Cryosphere
Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf
Earth-Surface Processes
Water Science and Technology
author_sort rosier, sebastian h. r.
spelling Rosier, Sebastian H. R. Gudmundsson, G. Hilmar 1994-0424 Copernicus GmbH Earth-Surface Processes Water Science and Technology http://dx.doi.org/10.5194/tc-14-17-2020 <jats:p>Abstract. 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. </jats:p> Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf The Cryosphere
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title Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf
title_unstemmed 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_short 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
topic Earth-Surface Processes
Water Science and Technology
url http://dx.doi.org/10.5194/tc-14-17-2020
publishDate 2020
physical 17-37
description <jats:p>Abstract. 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. </jats:p>
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author Rosier, Sebastian H. R., Gudmundsson, G. Hilmar
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author_sort rosier, sebastian h. r.
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description <jats:p>Abstract. 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. </jats:p>
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spelling Rosier, Sebastian H. R. Gudmundsson, G. Hilmar 1994-0424 Copernicus GmbH Earth-Surface Processes Water Science and Technology http://dx.doi.org/10.5194/tc-14-17-2020 <jats:p>Abstract. 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. </jats:p> Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf The Cryosphere
spellingShingle Rosier, Sebastian H. R., Gudmundsson, G. Hilmar, The Cryosphere, Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf, Earth-Surface Processes, Water Science and Technology
title 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_short 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
title_unstemmed Exploring mechanisms responsible for tidal modulation in flow of the Filchner–Ronne Ice Shelf
topic Earth-Surface Processes, Water Science and Technology
url http://dx.doi.org/10.5194/tc-14-17-2020