Near surface measurements with a Doppler current profiler

The ability of the RD instruments 1200-kHz Doppler current profiler to measure currents in the near-surface layer is discussed. Data are presented from tests where an RD system was mounted on a bottom sled in an upward-looking mode. The sled was towed by a carriage at precise speeds in a test basin with and without waves. Data show mean flow errors with and without waves in all bins to the surface. Data were sampled at sufficient speed to look at wave particle velocities. An evaluation of that data is presented. An evaluation of sidelobe effects and sidelobe deflection techniques to obtain undistorted measurements is presented