NAVAL COMMAND CONTROL AND OCEAN SURVEILLANCE CENTER RDT AND E DIV SAN DIEGO CA
The objective of this effort is to test the practicality of an instrument that uses the reflection coefficient modulated radiance shape from reflection to measure the roughness of the sea surface. Conceptually, this instrument would be used aboard ship to remotely sense the ocean wave spectrum of the sea surface ideally, the ocean wave spectrum covered by this instrument would range from very long wavelengths, on the order of decameters, to very short wavelengths, on the order of centimeters. A series of wave tank measurements made at the Scripps Institution of Oceanography SIO, San Diego, CA, clearly show that the technique is impractical. The technical difficulties are associated with the failure of several necessary assumptions of shape from reflection. The first assumption is that the sky illumination source is nearly isotropic in practice, this assumption is not valid. The second assumption is that the nonlinear relationship between the reflection coefficient and wave slop is not a fundamental limiting factor in practice, the sensitivity of the reflection coefficient to incidence angle appears to be a limiting factor. The technique of measuring the ocean wave spectrum by shape from reflection is not viable and should not be pursued.