Sea bottom topography with X-band SLAR: the relation between radar imagery and bathymetry

On 19 January 1988, and experiment was carried out to establish the positional relation between corresponding features in radar imagery and bottom topography. The radar measurements were done with the Dutch Digital SLAR, an X-band HH polarized SLAR system. The experiment look place in an area 30 km off the Dutch coast where the bottom topography is dominated by sand waves with a height between 2 and 6 m and a crest-to-crest distance of typically 500 m at a depth of 22 m. Ground data were recorded from two ships near the centre of the test area and from the Measuring Platform Noordwijk, 20 km from the test area. By comparing the radar images showing sand waves with digitized maps of depth and bottom slope it is concluded that the extremes in the radar backscatter are located right above regions with maximum bottom slope, within a positional accuracy of 30 m. This is in excellent agreement with predictions by simple relaxation models of the imaging mechanism.