ASA 129th Meeting - Washington, DC - 1995 May 30 .. Jun 06
4pUW13. Effects of bottom type variability on modeled backscattered levels
of a high-frequency sonar.
Kristen D. Savage
Roger W. Meredith
Naval Res. Lab., Code 7174, Stennis Space Center, MS 39529
Results investigating the effects of variable bottom composition on
modeled high-frequency backscattered levels are presented for a typical shallow
water, range-dependent environment. The modeled environment consisted of a
single sound-speed profile, a flat sea bottom with range-dependent bottom
composition, and a benign sea surface. Coarse and fine grain sandy areas were
partitioned in range to create range dependence. Bottom backscattering and
reflection loss for each partition were obtained from the recent University of
Texas high-frequency ocean bottom backscatter model [N. P. Chotiros and F. A.
Boyle, 3264(A) (1994)]. Differences of 5 dB were discernible between
the fine--coarse--fine sand bottom and a range-independent fine sand bottom for
ranges <500 m. The trend and structure of the backscattered levels were nearly
identical for both bottom types. Differences of 42 dB for ranges <500 m were
visible in the modeled backscattered level of the fine--coarse--fine sand
bottom and the coarse--fine--coarse sand bottom. The trend and structure of the
backscattered levels were also different. In all cases, surface reverberation
had a strong impact on the backscattered levels, trends, and structures. [Work
supported by MCM Tactical Environmental Data Systems (MTEDS) under Program
Element 62435N.]