| Popis: |
The acoustic reflection from an ice sheet in the arctic, as observed by an upward looking sonar, is simulated. The reflection from a smooth ice sheet is modeled using OASES, using material properties that may be found in the published literature. Depending on the bandwidth of the signal, specular reflections from the top and bottom of the ice, as well as one or more resonances that are identified as leaky Lamb waves should be detectable. If the speed of the Lamb wave is faster than the speed of sound in water, it will leak energy back into the water. The leaky Lamb wave has a characteristic resonant frequency that is a function of the ice thickness and shear speed. The reflection and backscatter from a rough ice sheet is modeled using SPECFEM2D. Scattering from a rough interface may obscure the expected signals, depending on the severity of the roughness. [Work supported by ONR, Ocean Acoustics Program.] |
