ASA 124th Meeting New Orleans 1992 October

5pUW7. Low-frequency distant surface/near-surface reverberation measurements in the Gulf of Alaska.

Roger C. Gauss

Raymond J. Soukup

Naval Res. Lab., Washington, DC 20375

C. Scott Hayek

Johns Hopkins Univ.

Distant reverberation measurements in the surface/near-surface and air--sea interaction experiment in the Gulf of Alaska (February/March 1992) were designed to assess the Doppler and spatial characters of primarily low grazing angle reverberation as functions of frequency environmental conditions, and source steering angle. Twenty-two tests using cw and HFM pulses of 8- to 12-s duration were conducted during a variety of sea conditions, at wind speeds ranging from 4 to 19 m/s. These data were collected simultaneously at two frequencies (usually 250 and 1000 Hz). The data illustrate the contrast in the spectral and temporal characteristics of long-range reverberation (20 to 30 km) between low sea states where fish scattering is important and higher sea states where subsurface bubbles are important.