CHARACTERISTICS OF SOUND REFLECTED FROM SEA-ICE

This paper presents a probabilistic analysis of the angular spectra at the water-ice boundary for arctic regions with various hydrophysical characteristics, i.e., in shallow and deep seas. The ice cover of a de ep sea is formed by two-year-old ice and solid ice fields, while the i ce cover of a shallow sea is formed by one-year-old ice, The presence of cold and warm bodies of water separated by a hydrological frontal z one was taken into account for the shallow sea. Two kinds of geoacoust ical-bottom models were considered - a liquid one and an elasto-viscou s one. The calculations of the sound field were made for a frequency r egion of a few kilohertz. The probability distributions of the coeffic ient of coherent reflection from the ice were calculated for ice of di fferent ages: from one-year-old ice of thickness in the range 0.3 - 0. 7 m to solid ice fields of thickness greater. than 2.5 m. The mean and maximum likelihood coefficients of coherent reflection of sound were determined. It is shown that, in cold water, the reflection of sound f rom the ice is lower than in warm water and that taking the shear comp onent of the sound wave in the bottom into account diminishes the refl ection from ice due to changes in the angular spectrum.