Array of Ocean Bottom Tilt Current Meters: data from the EMSO-Azores observatory, 2019-2021

Date 2021-08-07
Temporal extent 2019-07-01 -2021-06-01
Author(s) Cannat MathildeORCID1, Matabos MarjolaineORCID2, Van Audenhaege LoicORCID2, Gayet Nicolas2, Wheeler BenjaminORCID3, Souradeep Mahato3, Sarradin Pierre-MarieORCID2, Sarrazin JozeeORCID2, Legrand JulienORCID2
Affiliation(s) 1 : CNRS, IPGP, FRANCE
2 : IFREMER Institut Carnot EDROME
3 : IPGP, France
DOI 10.17882/76001
Publisher SEANOE
Keyword(s) Mid-Atlantic Ridge, EMSO-Azores, EMSO, Hydrothermal Vents, Lucky Strike, Eiffel Tower, Crystal, Montsegur, current velocity, current direction, near seafloor seawater temperature, Time-series, MoMARSAT2019, MoMARSAT2020, MoMARSAT2021

This dataset contains current data acquired between july 2019 and June 2021 using 6 TCM-3 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 6 TCM-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 the metadata file.

Licence CC-BY
Utilisation EMSO data are published without any warranty, express or implied. The user assumes all risk arising from his/her use of EMSO data. EMSO data are intended to be research-quality and include estimates of data quality and accuracy, but it is possible that these estimates or the data themselves contain errors. It is the sole responsibility of the user to assess if the data are appropriate for his/her use, and to interpret the data, data quality, and data accuracy accordingly. EMSO welcomes users to ask questions and report problems to the contact addresses listed in the data files or on the EMSO web page.
Sensor metadata


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


  • Regional node: Emso-Azores
  • Site: Lucky Strike hydrothermal field
  • coordinates: see Tthe metadata file


Momarsat 2019 and 2020 cruises and


Momarsat 2021 cruise

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_Azores2019_2021.doc.

Sensor setup - Data management

  • Real time data transmission: No
  • Data storage in the Communication and storage unit (COSTOF2): No
  • Data storage in the instrument: Full
File Size Format Processing Access
Metadata 53 KB PDF Open access
42 MB TEXTE Raw data Access on demand until 2023-01-01
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How to cite 

Cannat Mathilde, Matabos Marjolaine, Van Audenhaege Loic, Gayet Nicolas, Wheeler Benjamin, Souradeep Mahato, Sarradin Pierre-Marie, Sarrazin Jozee, Legrand Julien (2021). Array of Ocean Bottom Tilt Current Meters: data from the EMSO-Azores observatory, 2019-2021. SEANOE.