ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06

3aUW6. Seismoacoustic ultrasonic modeling characterization of sea ice processes.

Jacques R. Chamuel

Sonoquest Adv. Ultrason. Res., P.O. Box 81153, Wellesley Hills, MA 02181-0001

Sea ice processes affect the elastic properties, structure, and boundaries of the ice cover, and change the composition and acoustic properties of the top water layer underneath the ice. Upward refraction in the water creates substantial interaction between underwater acoustic waves and the ice cover influencing long-range low-frequency propagation. In order to develop a basic understanding of sea ice processes, it is essential to characterize seismoacoustic phenomena associated with sea ice growth, melting, refreezing, cracking, ridging, and rafting. Controlled laboratory experiments were conducted to study diverse transient liquid/solid seismoacoustic wave phenomena. Examples from scaled ultrasonic modeling results are presented characterizing near-grazing Scholte wave backscattering from trenches at liquid/solid interfaces, effective attenuation of flexural waves from horizontal refraction, seismic profiling from 45(degrees) oblique boreholes, viscous waves in ice suspensions, variability of shear wave speed in sea ice cores, edge wave propagation along truncated and range-dependent apex angle wedges, focused multiple scattering, and finger-rafting. The findings provide physical insight into high-latitude seismoacoustic oceanography and contribute to the interpretation of Arctic field data. [Work supported by ONR.]