On the controversial leaky Rayleigh wave at a water/ice interface

Abstract

To the author's knowledge, no experimental data have been published to date isolating and demonstrating the existence of the controversial leaky Rayleigh wave originating at a water/ice interface. In this paper, ultrasonic laboratory results are presented demonstrating the existence of a leaky Rayleigh wave at a water/ice interface not meeting Brower's (1979) existence condition. The measured phase velocity of transient leaky Rayleigh waves is about 8% higher than the free Rayleigh wave velocity from the air/ice interface. The refracted shear wave amplitude is very small compared to the leaky Rayleigh wave. The received signal is dominated by the leaky Rayleigh wave when the receiver is simultaneously close to the source and at a distance of about one Scholte wavelength from the interface. Substantial energy is associated with the leaky Rayleigh wave indicating that it may be important to account for the contribution of the leaky Rayleigh wave in the problem of scattering from rough water/ice interfaces. The leaky Rayleigh wave is very susceptible to the presence of surface cracks in the ice. The reported findings provide physical insights into arctic acoustics and may contribute to the interpretation of arctic acoustic data. [Work supported by ONR.]