Array of Ocean Bottom Tilt Current Meters: data from the EMSO-Azores observatory, 2018-2019

This dataset contains current data acquired between Auguest 2018 and June 2019 using 3 TCM3 Ocean Bottom Tilt Current Meters installed next to the Tour Eiffel, Montségur and Crystal hydrothermal vent sites.

The TCM-3 Ocean Bottom Tilt Current Meter from Lowell Instruments LLC (North Falmouth, MA, USA) measures current using the drag-tilt principle. The logger is buoyant and is anchored to the bottom via a short flexible tether. Drag from moving water tilts the logger in the direction of flow. The logger’s accelerometer and magnetometer channels are used to record the amount of tilt and direction of tilt (compass bearing). The array comprises 3 currentmeters, deployed near the Tour Eiffel, Montségur and Crystal hydrothermal vent sites. It is not connected to an energy node. The currentmeter's internal clocks are set to UTC time before deployment. Clock drift after recovery is not implemented in data but added as metadata in file Sensor Metadata.


Cross-discipline, Physical oceanography


Mid-Atlantic Ridge, EMSO-Azores, EMSO, Hydrothermal Vents, Lucky Strike, Eiffel Tower, Crystal, Montsegur, current velocity, current direction, near seafloor seawater temperature, Time-series, MoMARSAT2018, MoMARSAT2019


37.30134N, 37.2888S, -32.275618E, -32.27982W



  •  temperature (°C)
  • current velocity (m/s)
  • current direction (° from N)


  • Regional node: Emso-Azores
  • Site: Lucky Strike hydrothermal field
  • coordinates: see Table_TCM3EMSO_Azores 2018-2019.xls


Cruise: CANNAT Mathilde, LEGRAND Julien MOMARSAT2018 cruise, RV L'Atalante,


Cruise: SARRADIN Pierre-Marie, LEGRAND Julien (2019) MOMARSAT2019 cruise, RV Pourquoi pas ?

Operating parameters

For deployments near selected hydrothermal vents at the EMSO-Azores observatory, the accelerometer and magnetometer are configured with a burst interval of 1 minute, a burst rate of 8 Hz and a burst duration of 15 seconds. Temperature are recorded with a period of 1 minute.

Sensor metadata

The specifications of the magnetometer, accelerometer and temperature probes are as follows:

  • magnetometer: 3-axis magnetoresistive sensor and 12-bit A/D Converter, range +/- 1.3 Gauss, accuracy +/- 1° typical (nominal compass bearing), resolution < 0.001 Gauss, maximum recording rate 64 Hz, measurement duration 6 mS
  • accelerometer: 3-axis MEMS Accelerometer and 10-bit A/D Converter, software averaging: up to 32 values per measurement (25 samples per measurement are averaged when recording at 64 Hz), range +/- 2 g, accuracy < 0.01 g (enables 1° inclination determination), resolution < 0.001 g, maximum recording rate 64 Hz, measurement duration 0.625 ms per sample, 32 samples per recorded value (15.6 ms total sample time at 64 Hz 20 ms at 32 Hz or less)
  • thermistor: NTC Thermistor and 16-bit A/D Converter, low-pass filter rejects 50/60 Hz noise, range -5 to 30 °C (standard), -20 to 50 °C (extended), accuracy +/-0.1 °C (standard), +/-0.2 °C (extended), resolution < 0.01 °C, maximum rate 1 Hz, time constant 4 minutes typical (when plunged into an ice bath).

Sensor setup

Test and calibration A set of calibration coefficients for the magnetometer, accelerometer, and temperature channels are stored in the logger. The magnetometer and accelerometer coefficients are unique to each instrument while temperature coefficients are specific to each manufacturing lot. The calibration coefficients are applied upon recovery when the binary data is converted to text data. Data is provided as text, and not corrected for the time drift. Time drift is provided as metadata in Table_TCM3EMSO_Azores 2018-2019.xls.

Data management

  • Real time data transmission: No
  • Data storage in the Communication and storage unit (COSTOF2): No
  • Data storage in the instrument: Full


Sensor metadata
Current Data TCM3_1
20 MoTEXTRaw data
Current Data TCM3_2
20 MoTEXTRaw data
Current Data TCM3_3
19 MoTEXTRaw data
Temperature data TCM3_1
13 MoTEXTRaw data
Temperature data TCM3_2
13 MoTEXTRaw data
Temperature data TCM3_3
13 MoTEXTRaw data
Current Data TCM3_1
5 MoNetCDFRaw data
Current Data TCM3_2
5 MoNetCDFRaw data
Current Data TCM3_3
5 MoNetCDFRaw data
How to cite
Cannat Mathilde, Wheeler Benjamin, Chen Jie, Sarradin Pierre-Marie, Legrand Julien (2020). Array of Ocean Bottom Tilt Current Meters: data from the EMSO-Azores observatory, 2018-2019. SEANOE.

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