In-situ measurements of short wave modulation due to bottom topography

Abstract

Radar images often show features of bottom topography although radar waves do not penetrate the water. This imaging process is caused by bottom induced current variations which modulate the short waves and hence the radar backscatter intensity. Principally it is possible to deduce a transfer function from radar images to bottom topography. In the frame of the C-STAR project of the European Commission (Coastal Sediment Transport Assessment using SAR imagery) a field experiment had been performed to study the short wave modulation due to bottom topography. A special buoy system drifted across the study area off the Dutch coast measuring waves, wind and bottom profiles. The results clearly show correlations of short wave modulation and water depths.