The influence of the physical properties of ice on reflectivity

Abstract

A model for the plane-wave reflection coefficient from a layered elastic solid bounded on either side by a fluid half-space is developed and applied to study environmental factors affecting the reflectivity of smooth arctic ice. Experimental measurements of the internal friction in ice and snow are reviewed and applied to compute realistic attenuation profiles. An examination of the effect of ice layers conforming with measured temperature profiles in floe ice shows that the use of average values for sound speed and attenuation is an acceptable approximation for modeling purposes. A study of the reflectivity due to the absorption of shear and compressional waves demonstrates that shear wave attenuation is the most important loss mechanism from 20° to 60° incidence. The effect of an additional snow layer is to produce more attenuation without shifting the pattern of reflection nulls. Major results are presented for a frequency of 2 kHz. Data comparisons are performed from 0.5–3 kHz that show a limited qualitative agreement with the model.