气候变化领域集成服务门户(CCPortal): Sea ice thickness from air-coupled flexural waves

CCPortal

DOI	10.5194/tc-15-2939-2021
	Sea ice thickness from air-coupled flexural waves
	Romeyn R.; Hanssen A.; Ruud B.O.; Johansen T.A.
发表日期	2021
ISSN	19940416
起始页码	2939
结束页码	2955
卷号	15 期号:6
英文摘要	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 g1/4g20-80gcm 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 g1/4g48gHzgm. Our field data include ice ranging from g1/4g20-80gcm thickness with corresponding air-coupled flexural frequencies from 240gHz for the thinnest ice to 60gHz 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. © Author(s) 2021.
语种	英语
来源期刊	Cryosphere
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/202415
作者单位	Department of Geosciences, University of Tromsø - the Arctic University of Norway, Tromsø, 9037, Norway; Department of Earth Science, University of Bergen, Bergen, 5007, Norway; Department of Arctic Geology, The University Centre in Svalbard (UNIS), Longyearbyen, 9171, Norway
推荐引用方式 GB/T 7714	Romeyn R.,Hanssen A.,Ruud B.O.,et al. Sea ice thickness from air-coupled flexural waves[J],2021,15(6).
APA	Romeyn R.,Hanssen A.,Ruud B.O.,&Johansen T.A..(2021).Sea ice thickness from air-coupled flexural waves.Cryosphere,15(6).
MLA	Romeyn R.,et al."Sea ice thickness from air-coupled flexural waves".Cryosphere 15.6(2021).