Ocean Velocities from the ADCP

Aside from the CTDs and the moorings, there are also many instruments mounted to the ship that are constantly collecting data as we go. One of these is the Acoustic Doppler Current Profiler (ADCP), which measures how fast the water is moving under the ship. Much like a sonar, the instrument sends out a sound pulse, which is then scattered by small particles or plankton in the water. The ADCP listens to the echo and uses the so-called Doppler effect to calculate the velocity with which the particles (and thus the water) are moving. In this way, we can monitor the currents under the ship almost in real time!

The Antilles Current, just east of the Bahamas. This warm, shallow current flows north in the top 800 m with speeds of up to 60 cm/s (1.2 knots if you prefer) in this example. You can see the subsurface maximum of northward velocities measured by the ADCP.

This figure shows us crossing the Antilles current earlier this week. The ADCP shows strong subsurface currents down as far as 800 meters! 

Charlotte