Imaging of Ocean Waves by SAR
Abstract
A model is presented for Synthetic Aperture Radar imaging of the ocean surface. The model attempts to avoid making assumptions about the relative importance of various imaging mechanisms. The model is applied to three issues, the focus setting, the asymmetry in the images obtained with obtained with opposite airplane flight directions, and the azimuthal image shift of features on range directed waves. The focus setting depends on a combination of the velocity of the pattern being imaged and on the velocity of the Bragg scatterers. The focus setting does not depend significantly on the imaging mechanism, that is velocity bunching, modulation of Bragg waves, and so on. Comparisons of our model predictions are made with the TOWARD results. A simple analytic prediction is obtained for the complete curve of the observed energy in swell versus the focus setting. The maximum of this curve is predicted to occur at one-half of the phase speed of the swell for azimuthally traveling swell and a simple explanation is provided for this result. The asymmetry in the visibility of the swell obtained by flying with or against the long waves is estimated. The asymmetry arises from competition between velocity bunching and hydrodynamic modulations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 01, 1988
- Accession Number
- ADA203604
Entities
People
- F. S. Henyey
- J. A. Wright
- R. L. Schult