Ocean Surface Roughness from Infrared Measurements: A Failure of Shape from Reflection
Abstract
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1993
- Accession Number
- ADA278008
Entities
People
- K. D. Anderson
Organizations
- Naval Command, Control and Ocean Surveillance Center