Environmental Effects on Low Frequency Transmission Loss in the Gulf of Mexico
Final rept. 1 Oct 1979-30 Sep 1980
NAVAL OCEAN RESEARCH AND DEVELOPMENT ACTIVITY STENNIS SPACE CENTER MS
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Acoustic transmission loss data were acquired during Cruise 1 of the CHURCH STROKE III Exercise of July 1979. Initial comparisons of observed transmission loss data, with pre-exercise model predictions made using the ASTRAL model with historical environmental data inputs indicated a considerable degree of disagreement. A series of post-exercise model runs were undertaken to isolate the environmental factors contributing to the observed disagreement. Model runs using a range-dependent normal mode model SNAP were made using a geoacoustic description of seafloor. Good agreement was attained for detailed structure comparisons. Estimates made using the model ASTRAL, together with a bottom loss description derived from the same geoacoustic description of the seafloor, matched the observed levels quite well in an average sense. Since the attenuation estimates were derived from those resulting from the BEARING STAKE Exercise, some implications as to the validity of geoacoustic parameter extrapolation are apparent. Additional implications arise with respect to the degree to which pre-exercise ambient noise estimates agree with observations made during CHURCH STROKE III.
- Physical and Dynamic Oceanography