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On the propagation of acoustic-gravity waves under elastic ice sheets

Abdolali, Ali, Kadri, Usama, Parsons, Wade and Kirby, James T. 2018. On the propagation of acoustic-gravity waves under elastic ice sheets. Journal of Fluid Mechanics 837 , pp. 640-656. 10.1017/jfm.2017.808

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Abstract

The propagation of wave disturbances in water of varying depth bounded above by ice sheets is discussed, accounting for gravity, compressibility and elasticity effects. Considering the more realistic scenario of elastic ice sheets reveals a continuous spectrum of acoustic–gravity modes that propagate even below the cutoff frequency of the rigid surface solution where surface (gravity) waves cannot exist. The balance between gravitational forces and oscillations in the ice sheet defines a new dimensionless quantity Ka. When the ice sheet is relatively thin and the prescribed frequency is relatively low (Ka≪1), the free-surface bottom-pressure solution is retrieved in full. However, thicker ice sheets or propagation of relatively higher frequency modes (Ka≫1) alter the solution fundamentally, which is reflected in an amplified asymmetric signature and different characteristics of the eigenvalues, such that the bottom pressure is amplified when acoustic–gravity waves are transmitted to shallower waters. To analyse these scenarios, an analytical solution and a depth-integrated equation are derived for the cases of constant and varying depths, respectively. Together, these are capable of modelling realistic ocean geometries and an inhomogeneous distribution of ice sheets.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Mathematics
Publisher: Cambridge University Press (CUP)
ISSN: 0022-1120
Date of First Compliant Deposit: 5 March 2019
Date of Acceptance: 5 November 2017
Last Modified: 19 Jul 2019 13:55
URI: http://orca.cf.ac.uk/id/eprint/118857

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