Acoustic Doppler Current Profiler (ADCP)

An Acoustic Doppler Current Profiler (ADCP) is an instrument that measures water velocity across a range of depths by transmitting acoustic pings and reading the Doppler shift of energy backscattered from particles and plankton drifting with the flow. Each of three or four slanted transducer beams resolves one velocity component; geometry combines them into a horizontal and vertical current vector. The water column is divided into range bins, so one deployment returns a full velocity profile. ADCPs are mounted on hulls, moorings, and lowered CTD frames. Typical instruments run at 75 kHz to 600 kHz, trading range against bin resolution: lower frequencies reach hundreds of meters.