4pUW5. Measurements and modeling of low-frequency bottom-scattering strengths from the Scotian Continental Rise.

Session: Thursday Afternoon, December 5

Time: 2:37

Author: Roger C. Gauss
Location: Naval Res. Lab., Washington, DC 20375-5350
Author: Charles Holland
Location: Planning Systems, Inc., McLean, VA 22102
Author: Joseph M. Fialkowski
Location: Planning Systems, Inc., McLean, VA 22102
Author: Peter Neumann
Location: Planning Systems, Inc., McLean, VA 22102


A series of low-frequency (190--310 Hz), bottom-backscattering strength measurements were made on the Scotian Continental Rise in August 1993 using combinations of short-duration cw and HFM signals. Grazing angles realized were between 5 and 30 deg. A characteristic of many sites were strong (on the order of 10 dB) oscillations with a grazing angle superimposed on generally Mackenzian backscatter. The oscillatory behavior is due to caustics within the sediment, i.e., a propagation effect. Previous modeling of this general area [P. D. Mourad and D. R. Jackson, J. Acoust. Soc. Am. 94, 344--358 (1993)] predicted such an oscillatory behavior but only for unrealistic sediment sound--speed profiles. An alternative bottom-scattering model is proposed with the goal of predicting the observed scatter using a more realistic geoacoustic model. Measurement/model comparisons will be presented for several representative sites. [Work supported by SPAWAR, NRL, and ONR.]

ASA 132nd meeting - Hawaii, December 1996