E. J. Yoerger
Naval Res. Lab., Code 7174, Stennis Space Center, MS 39529
Suzanne T. McDaniel
Penn State Univ., State College, PA
The underwater acoustic propagation path for the forward scattering of energy from the sea surface is treated as a linear, time-varying random communications channel in the application of the Helmholtz--Kirchhoff integral formulation of this problem. The model used for data comparisons utilizes the bifrequency system function (Gamma)((omega),(omega)') developed by McDaniel [IEEE J. Ocean. Eng. 17, 216--221 (1992)] for the temporal response from a rough surface. The data analyzed for this work were obtained from a shallow-water high-frequency acoustic experiment conducted on the Baltic Sea during May 1993. Acoustic data included measurements of surface forward-scattering, surface reverberation, and direct-path intensities. These were made utilizing two large stationary towers resting on the seafloor. Each tower was equipped with horizontal and vertical receiving arrays anchored 7.6 m above the flat bottom depth of 30 m. Concurrent environmental measurements including wave heights, sound velocity profiles, and sample cores were made. The results presented here are for the surface forward-scattered measurements made at 20, 40, 60, and 90 kHz. [Work supported by the Office of Naval Research, Program Element 61153N, with technical management provided by the Naval Research Laboratory, Stennis Space Center, MS.]