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

Date 2020-05
Temporal extent 2018-08-17 -2019-06-25
Author(s) Cannat MathildeORCID1, Wheeler BenjaminORCID2, Chen Jie2, Sarradin Pierre-MarieORCID3, Legrand JulienORCID3
Affiliation(s) 1 : CNRS, IPGP, France
2 : IPGP, France
3 : Ifremer, France
DOI 10.17882/74378
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, MoMARSAT2018, MoMARSAT2019
Abstract

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.

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

Parameters

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

Location

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

Installation

Cruise: CANNAT Mathilde, LEGRAND Julien MOMARSAT2018 cruise, RV L'Atalante, http://dx.doi.org/10.17600/17000500

Recovery

Cruise: SARRADIN Pierre-Marie, LEGRAND Julien (2019) MOMARSAT2019 cruise, RV Pourquoi pas ?https://doi.org/10.17600/18001110

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
Data
File Size Format Processing Access
Sensor metadata 16 KB XLS, XLSX Open access
Sites 8 KB XLS, XLSX Open access
20 MB TEXTE Raw data Access on demand until 2021-12-31
20 MB TEXTE Raw data Access on demand until 2021-12-31
19 MB TEXTE Raw data Access on demand until 2021-12-31
13 MB TEXTE Raw data Access on demand until 2021-12-31
13 MB TEXTE Raw data Access on demand until 2021-12-31
13 MB TEXTE Raw data Access on demand until 2021-12-31
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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. https://doi.org/10.17882/74378