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dc.contributor.authorRomeyn, Rowan
dc.contributor.authorHanssen, Alfred
dc.contributor.authorRuud, Bent Ole
dc.contributor.authorJohansen, Tor Arne
dc.date.accessioned2021-06-29T08:58:36Z
dc.date.available2021-06-29T08:58:36Z
dc.date.issued2021-06-28
dc.description.abstractAir-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.en_US
dc.identifier.citationRomeyn, Hanssen, Ruud, Johansen. Sea ice thickness from air-coupled flexural waves. The Cryosphere. 2021en_US
dc.identifier.cristinIDFRIDAID 1918999
dc.identifier.doi10.5194/tc-15-2939-2021
dc.identifier.issn1994-0416
dc.identifier.issn1994-0424
dc.identifier.urihttps://hdl.handle.net/10037/21600
dc.language.isoengen_US
dc.publisherEuropean Geosciences Union (EGU)en_US
dc.relation.ispartofRomeyn, R. (2022). Cracking into Cryoseismology. (Doctoral thesis). <a href=https://hdl.handle.net/10037/24344>https://hdl.handle.net/10037/24344</a>.
dc.relation.journalThe Cryosphere
dc.rights.accessRightsopenAccessen_US
dc.rights.holderCopyright 2021 The Author(s)en_US
dc.subjectVDP::Mathematics and natural science: 400::Geosciences: 450en_US
dc.subjectVDP::Matematikk og Naturvitenskap: 400::Geofag: 450en_US
dc.titleSea ice thickness from air-coupled flexural wavesen_US
dc.type.versionpublishedVersionen_US
dc.typeJournal articleen_US
dc.typeTidsskriftartikkelen_US
dc.typePeer revieweden_US


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