Retrieval of underwater bottom topography by using synthetic aperture radar (SAR)
Synthetic aperture radar (SAR) is an active instrument which yields high-resolution images in the microwave frequency band. When applied to image the ocean, it detects small variations in the small-scale sea surface roughness. These roughness variations can result, for example, from variations in surface current speed caused by a tidal flow over shallow sandbanks. Although the microwaves cannot penetrate into the water body, SAR can retrieve information on underwater bottom topography (or bathymetry) indirectly by measuring variations in the small-scale sea surface roughness.
Underwater bottom topographic features, such as sandbanks and ridges, become visible on radar images of the sea surface only when there is a current present (usually a tidal current) which flows over them. This causes local perturbations to the current which in turn modulates the sea surface...
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