SAR Detection of Ship-Generated Turbulent and Vortex Wakes
Abstract
A frequently observed ship wake feature in Synthetic Aperture Radar (SAR) images is a dark, narrow line along the ship track. These features have been termed turbulent wakes, although it is not clear that turbulence alone is responsible for their appearance. It has been suggested that vortices produced by the ship's hull may be responsible for the suppression of surface waves near the ship track and an enhancement of the waves near the edge of the smoothed area. The primary purpose of this study was to use a hydrodynamic model for ship-generated vortices as input to existing radar backscatter models, and to use this hybrid model to produce simulated SAR ship wake signatures for comparison with actual measurements. For the limited number of cases considered, the simulated wake signatures agreed closely to those observed in actual SAR data. Our results also indicated that the SAR signatures are related to the vortex currents under low wind conditions and to the strain rates associated with the ship-generated vortices under high winds. Additional studies included the radar resolution dependence of SAR ship wake features as well as examination of the Fourier transform of a ship wake image for information which could be used in an automatic detection algorithm. Keywords: Radar images; Radar/ship signatures; Optical radar; Surface waves perturbations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 01, 1985
- Accession Number
- ADA221563
Entities
People
- C. V. Swanson
- David R. Lyzenga
- J. D. Lyden
- R. A. Shuchman