Sea ice thickness from air-coupled flexural waves
Air-coupled flexural waves (ACFWs) appear as wave trains of constant frequency that arrive in advance of the direct air wave from an impulsive source travelling over a floating ice sheet. The frequency of these waves varies with the flexural stiffness of the ice sheet, which is controlled by a combi...
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Online Access: | https://hdl.handle.net/10037/21600 https://doi.org/10.5194/tc-15-2939-2021 |
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ftunivtroemsoe:oai:munin.uit.no:10037/21600 2023-05-15T16:40:38+02:00 Sea ice thickness from air-coupled flexural waves Romeyn, Rowan Hanssen, Alfred Ruud, Bent Ole Johansen, Tor Arne 2021-06-28 https://hdl.handle.net/10037/21600 https://doi.org/10.5194/tc-15-2939-2021 eng eng European Geosciences Union (EGU) Romeyn, R. (2022). Cracking into Cryoseismology. (Doctoral thesis). https://hdl.handle.net/10037/24344 . The Cryosphere Romeyn, Hanssen, Ruud, Johansen. Sea ice thickness from air-coupled flexural waves. The Cryosphere. 2021 FRIDAID 1918999 doi:10.5194/tc-15-2939-2021 1994-0416 1994-0424 https://hdl.handle.net/10037/21600 openAccess Copyright 2021 The Author(s) VDP::Mathematics and natural science: 400::Geosciences: 450 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 Journal article Tidsskriftartikkel Peer reviewed publishedVersion 2021 ftunivtroemsoe https://doi.org/10.5194/tc-15-2939-2021 2022-03-09T23:57:52Z Air-coupled flexural waves (ACFWs) appear as wave trains of constant frequency that arrive in advance of the direct air wave from an impulsive source travelling over a floating ice sheet. The frequency of these waves varies with the flexural stiffness of the ice sheet, which is controlled by a combination of thickness and elastic properties. We develop a theoretical framework to understand these waves, utilizing modern numerical and Fourier methods to give a simpler and more accessible description than the pioneering yet unwieldy analytical efforts of the 1950s. Our favoured dynamical model can be understood in terms of linear filter theory and is closely related to models used to describe the flexural waves produced by moving vehicles on floating plates. We find that air-coupled flexural waves are a real and measurable component of the total wave field of floating ice sheets excited by impulsive sources, and we present a simple closed-form estimator for the ice thickness based on observable properties of the air-coupled flexural waves. Our study is focused on first-year sea ice of ∼ 20–80 cm thickness in Van Mijenfjorden, Svalbard, that was investigated through active source seismic experiments over four field campaigns in 2013, 2016, 2017 and 2018. The air-coupled flexural wave for the sea ice system considered in this study occurs at a constant frequency thickness product of ∼ 48 Hz m. Our field data include ice ranging from ∼ 20–80 cm thickness with corresponding air-coupled flexural frequencies from 240 Hz for the thinnest ice to 60 Hz for the thickest ice. While air-coupled flexural waves for thick sea ice have received little attention, the readily audible, higher frequencies associated with thin ice on freshwater lakes and rivers are well known to the ice-skating community and have been reported in popular media. The results of this study and further examples from lake ice suggest the possibility of non-contact estimation of ice thickness using simple, inexpensive microphones located above the ice sheet or along the shoreline. While we have demonstrated the use of air-coupled flexural waves for ice thickness monitoring using an active source acquisition scheme, naturally forming cracks in the ice are also shown as a potential impulsive source that could allow passive recording of air-coupled flexural waves. Article in Journal/Newspaper Ice Sheet Sea ice Svalbard The Cryosphere Van Mijenfjorden University of Tromsø: Munin Open Research Archive Svalbard Van Mijenfjorden ENVELOPE(14.667,14.667,77.717,77.717) The Cryosphere 15 6 2939 2955 |
institution |
Open Polar |
collection |
University of Tromsø: Munin Open Research Archive |
op_collection_id |
ftunivtroemsoe |
language |
English |
topic |
VDP::Mathematics and natural science: 400::Geosciences: 450 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 |
spellingShingle |
VDP::Mathematics and natural science: 400::Geosciences: 450 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 Romeyn, Rowan Hanssen, Alfred Ruud, Bent Ole Johansen, Tor Arne Sea ice thickness from air-coupled flexural waves |
topic_facet |
VDP::Mathematics and natural science: 400::Geosciences: 450 VDP::Matematikk og Naturvitenskap: 400::Geofag: 450 |
description |
Air-coupled flexural waves (ACFWs) appear as wave trains of constant frequency that arrive in advance of the direct air wave from an impulsive source travelling over a floating ice sheet. The frequency of these waves varies with the flexural stiffness of the ice sheet, which is controlled by a combination of thickness and elastic properties. We develop a theoretical framework to understand these waves, utilizing modern numerical and Fourier methods to give a simpler and more accessible description than the pioneering yet unwieldy analytical efforts of the 1950s. Our favoured dynamical model can be understood in terms of linear filter theory and is closely related to models used to describe the flexural waves produced by moving vehicles on floating plates. We find that air-coupled flexural waves are a real and measurable component of the total wave field of floating ice sheets excited by impulsive sources, and we present a simple closed-form estimator for the ice thickness based on observable properties of the air-coupled flexural waves. Our study is focused on first-year sea ice of ∼ 20–80 cm thickness in Van Mijenfjorden, Svalbard, that was investigated through active source seismic experiments over four field campaigns in 2013, 2016, 2017 and 2018. The air-coupled flexural wave for the sea ice system considered in this study occurs at a constant frequency thickness product of ∼ 48 Hz m. Our field data include ice ranging from ∼ 20–80 cm thickness with corresponding air-coupled flexural frequencies from 240 Hz for the thinnest ice to 60 Hz for the thickest ice. While air-coupled flexural waves for thick sea ice have received little attention, the readily audible, higher frequencies associated with thin ice on freshwater lakes and rivers are well known to the ice-skating community and have been reported in popular media. The results of this study and further examples from lake ice suggest the possibility of non-contact estimation of ice thickness using simple, inexpensive microphones located above the ice sheet or along the shoreline. While we have demonstrated the use of air-coupled flexural waves for ice thickness monitoring using an active source acquisition scheme, naturally forming cracks in the ice are also shown as a potential impulsive source that could allow passive recording of air-coupled flexural waves. |
format |
Article in Journal/Newspaper |
author |
Romeyn, Rowan Hanssen, Alfred Ruud, Bent Ole Johansen, Tor Arne |
author_facet |
Romeyn, Rowan Hanssen, Alfred Ruud, Bent Ole Johansen, Tor Arne |
author_sort |
Romeyn, Rowan |
title |
Sea ice thickness from air-coupled flexural waves |
title_short |
Sea ice thickness from air-coupled flexural waves |
title_full |
Sea ice thickness from air-coupled flexural waves |
title_fullStr |
Sea ice thickness from air-coupled flexural waves |
title_full_unstemmed |
Sea ice thickness from air-coupled flexural waves |
title_sort |
sea ice thickness from air-coupled flexural waves |
publisher |
European Geosciences Union (EGU) |
publishDate |
2021 |
url |
https://hdl.handle.net/10037/21600 https://doi.org/10.5194/tc-15-2939-2021 |
long_lat |
ENVELOPE(14.667,14.667,77.717,77.717) |
geographic |
Svalbard Van Mijenfjorden |
geographic_facet |
Svalbard Van Mijenfjorden |
genre |
Ice Sheet Sea ice Svalbard The Cryosphere Van Mijenfjorden |
genre_facet |
Ice Sheet Sea ice Svalbard The Cryosphere Van Mijenfjorden |
op_relation |
Romeyn, R. (2022). Cracking into Cryoseismology. (Doctoral thesis). https://hdl.handle.net/10037/24344 . The Cryosphere Romeyn, Hanssen, Ruud, Johansen. Sea ice thickness from air-coupled flexural waves. The Cryosphere. 2021 FRIDAID 1918999 doi:10.5194/tc-15-2939-2021 1994-0416 1994-0424 https://hdl.handle.net/10037/21600 |
op_rights |
openAccess Copyright 2021 The Author(s) |
op_doi |
https://doi.org/10.5194/tc-15-2939-2021 |
container_title |
The Cryosphere |
container_volume |
15 |
container_issue |
6 |
container_start_page |
2939 |
op_container_end_page |
2955 |
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1766031032420663296 |