Acoustic Current Meters
Acoustic Current Meters
Aquadopp Current Meters use the Doppler effect to measure current velocities in the ocean environment. The instrument transmits a short pulse of sound, and then listens to its echo to measure the change in pitch or frequency. The change in pitch can determine the velocity of the current. The following diagram shows the major components of an Acoustic Current Meter instrument:
Sensor Head: contains 3 acoustic transducers, a tilt sensor, a temperature sensor and a pressure sensor.
Tilt Sensor: is located on a small daughter board attached to the sensor head. Aquadopp tilt sensors are designed for vertical orientation, but tilt sensors can be mounted at right angles for operating in horizontal orientation. Tilt sensors can be inverted 180 degrees, pointing up or down.
Temperature Sensor: is located internally on the sensor head.
Pressure Sensor: is located on the sensor head.
Compass: measures the earth's magnetic field. Together with the tilt sensor, the compass is able to obtain a heading for the Aquadopp.
Acoustic Current Meters on the Seafloor
Circulation Moorings
The NEPTUNE Regional Network has four Regional Circulation Moorings (RCM) that measure currents within the axial rift valley of Endeavour Ridge at the regional scale, and gauge the effect of hydrothermal venting on regional currents. Each mooring is comprised of three types of instruments including Accoustic Current Meters, CTDs, and Acoustic Doppler Current Profilers (ADCP). These instruments are fixed to a cable at various depths above the seafloor bottom, and measure the current velocity in 3 dimensions and physical properties such as temperature and salinity. The top of the cable is lifted by a large buoy which keeps the line vertical at all times.
NE Mooring
Aquadopp 2MHz 3000m symmetric A2L 2806
Aquadopp 2MHz 3000m symmetric A2L 2808
Aquadopp 2MHz 3000m symmetric A2L 2809
Aquadopp 2MHz 3000m symmetric A2L 2811
NW Mooring
Aquadopp 2MHz 3000m symmetric A2L 2599
Aquadopp 2MHz 3000m symmetric A2L 2781
Aquadopp 2MHz 3000m symmetric A2L 2795
Aquadopp 2MHz 3000m symmetric A2L 2878
SE Mooring
Aquadopp 2MHz 3000m symmetric A2L 2572
Aquadopp 2MHz 3000m symmetric A2L 2935
Aquadopp 2MHz 3000m symmetric A2L 3082
Aquadopp 2MHz 3000m symmetric A2L 3105
SW Mooring
Aquadopp 2MHz 3000m symmetric A2L 2334
Aquadopp 2MHz 3000m symmetric A2L 2760
Aquadopp 2MHz 3000m symmetric A2L 2802
Aquadopp 2MHz 3000m symmetric A2L 2882
Auxiliary Platforms
Nortek Aquadopp 2MHz 3000m symmetric A2L on ODP 889 Seismometer Auxiliary Platform
Nortek Aquadopp 2MHz 3000m symmetric A2L on ODP 1027 Seismometer Auxiliary Platform
Folger Pinnacle Platform
Nortek Aquadopp 2MHz 3000m symmetric A2L on Folger Pinnacle Platform