Vol. 6, No. 2, 67-81, 2007

Abstract
An improved radar imaging theory of marine sand wave signatures based on quasi-specular scattering is presented. For quasi-specular scattering from a rough ocean surface, the normalised radar cross section (NRCS) is proportional to the total variance of slopes created by ocean surface waves. Quasi-specular scattering becomes dominant at higher radar frequencies. The formulated theory is applicable to the X-band synthetic aperture radar (SAR) of TerraSAR-X, Germany's first civil national remote sensing satellite realised by a public-private partnership. The improved quasi-scattering theory contains the additional dependences on the up- and crosswind wave slopes, the angle between the upwind and perpendicular current direction to the sand wave crest, and the angle between the radar range direction and the upwind direction. The current-short surface wave interaction is described by weak hydrodynamic interaction theory in the relaxation time approximation. Detailed TerraSAR-X data with a spatial resolution of up to 1 m and up to 1.5 dB radiometric resolution will be used with the advantage to be nearly weather independent. The investigation area is the tidal channel of the Lister Tief in the German Bight of the North Sea characterised by large morphological changes of four-dimensional submarine bedforms in time and space. Due to the high spatial resolution of the TerraSAR-X data it will be possible to identify sea surface roughness variations caused by meso-scale sand waves < 300 m widths at water depths < 40 m and associated unique oceanographic phenomena such as up- and downwelling events, turbulence, and eddies. The proposed measurement configuration and all needed in situ data are described. Advanced knowledge of transport characteristics of marine sand waves is very important for ship navigation and coastal zone management.

ISSN 1729-3782