Laser doppler velocimetry on the sea floor

Advantages of the laser Doppler velocimetry method, as well as current status are reviewed. The unique problems of applying this tecnnique to sediment transport studies in the deep sea are discussed, followed by how these problems were overcome. An autonomous two-axis backscatter instrument is described which profiles the horizontal velocity in the bottom 0-0.5 m of the benthic boundary layer under microprocessor control. Data is stored as velocity time series on a Sea Data tape recorder following in-situ processing of the Doppler signal.