REFLECTIONS FROM THE OCEAN SURFACE AND BOTTOM.
COLUMBIA UNIV DOBBS FERRY N Y HUDSON LABS
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The arrivals from a shallow acoustic source have a large fluctuation in energy, particularly near interference minima. However, an observed experimental dependence of mean energy upon range was in excellent agreement with a ray calculation which assumed that the surface reflection coefficient is 1. Good experimental agreement was also obtained with a ray solution to the reflections from a compound bottom, although the assumed thickness of the layering was only twice that of the impinging acoustic wavelength. The reflection of acoustic pulses from the ocean surface has been examined experimentally for sea states ranging from 1 to 3 and for frequencies from 160 to 1360 Hz. Power spectra of the time sequence of the intensities of successive reflections show the wave structure of the ocean surface. However, different acoustic wavelengths see the same surface in a different way. Apparently, in order to produce changes of intensity, the surface structure must have dimensions which are several times as great as the acoustic wavelength. Author