ASA 124th Meeting New Orleans 1992 October

5pUW5. Low-frequency volume scatter and accompanying bioacoustic measurements in the Gulf of Alaska.

Mark J. Vaccaro

Joseph M. Monti

Naval Undersea Warfare Ctr., Detachment New London, New London, CT 06320

Al Brooks

Omni Analysis, Waterford, CT

Volume scattering from 200 to 1500 Hz was measured during the Gulf of Alaska surface scatter and air/sea interaction experiment occurring in February 1992. Scattering strength as a function of frequency and depth was measured and layer strength and column strength were calculated using a vertically bistatic measurement technique developed by Stockhausen and Figoli [SACLANT ASW Research Center Technical Report No. 225, 15 May 1973]. These measurements were accompanied by concurrent measurements of size/depth distributions of the fish population present using a dual beam echosounder system. Fish distributions were used to predict layer and column strength by employing the NUWC Interval Column Strength Model developed by Saenger et al. [Naval Underwater Systems Center Technical Report No. 9001 (31 December 1991)]. Comparisons of the measured and predicted results show that low-frequency scattering resonances may be related to biologics.