Donald G. Albert
U.S. Army Cold Regions Res. and Eng. Lab., 72 Lyme Rd., Hanover, NH 03755-1290
The amplitude and waveform shape of atmospheric acoustic pulses propagating horizontally over a seasonal snow cover are profoundly changed by the air forced into the snow pores as the pulses move over the surface. Attenborough's four-parameter, rigid-ice-frame porous treatment of snow is applied to the inverse problem, where the observed waveform is used to determine the acoustic parameters of the snow. Horizontally propagating acoustic pulses were generated using blank pistol shots fired 1 m above various seasonal snow covers and measured by surface microphones 60 m away. Various inversion strategies, both frequency and time domain, were investigated to determine automatically the acoustic parameters that accurately predict the observed waveforms. Preliminary results show that the effective flow resistivity and depth of the snow are the controlling parameters. [Work supported by the Directorate of Research and Development, U.S. Army Corps of Engineers.]