SAR imagery and surface truth comparisons of internal waves in Georgia Strait, British Columbia, Canada

Abstract

The surface roughness patterns caused by internal waves in Georgia Strait on the west coast of Canada were used as an imagery target for the SEASAT synthetic aperture radar (SAR) on July 30, 1978. In these patterns there is strong modulation of short surface waves including the Bragg wavelength for resonant microwave reflection. In the sheltered waters of the strait, the complicating effects of longer waves are greatly reduced. The roughness patterns were also observed with an airborne SAR, by aerial photography, and by shipborne surface roughness and subsurface current measurements. The data show the response of the SAR's to the anisotropic roughness patterns measured by the ship. The SAR signal intensity is shown to be moderately correlated with Bragg wave or total roughness energy, but not with the facet area aligned to give specular reflection.