Metadata Report for BODC Series Reference Number 768885

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Data quality report M9801290D1

In LCDAEL01 (current direction), several datacycles were flagged because they are spikes. In LCEWEL01 (current eastward component), datacycle 3818 was flagged because it is a spike.

Data Access Policy

SIMORC data access conditions

The data collated and held at BODC on behalf of the SIMORC project are restricted. However, the data will be available to download from the Official SIMORC Website, as part of the project protocol. The data set will initially include data from the oil companies TOTAL, Shell and BP.

Narrative Documents

InterOcean Spherical Solid State Sensor Current Meter S4 series

The S4 family are self-contained current measuring sensors enclosing all necessary solid state electronics for acquiring, processing and outputting data. Data retrieval is accomplished through a serial port without opening the instrument.

The spherical shape of the S4 is a contributing factor in the rejection of the vertical components of water movement and there are no protruding parts or sensor support structures to interfere with the water flow.

The S4 measures the magnitude and direction of the horizontal current motion of the water. Water flows through the electromagnetic field created by the instrument, thereby producing a voltage which is proportional to the magnitude of the water velocity past the sensor. This voltage is then sensed by two pairs of titanium electrodes located symmetrically on the equator of the spherical housing which forms the sensor.

Manufacturer's specifications: Meter (sphere, diameter 25cm) is designed for depths down to 1000m (S4 standard: glass-filled cycloaliphalic epoxy construction with grooved surface for hydrodynamic stability) or down to 6000m (S4D, deep: annealed borosilicate glass version with smooth surface). The meter is shackled directly into the mooring cable by means of an axial titanium load bearing shaft.

Meter comprises:-

1. Electromagnetic, 2 axis current speed sensor, range 0 to 350cm/s (standard) 0 to 50 and 0 to 100cm/s (optional), resolution 0.2cm/s (standard) 0.03cm/s (0 to 50 range) 0.06cm/s (0 to 100 range), accuracy 2 per cent reading +/- 1cm/s. The sensor responds to the component of flow normal to its vertical axis.

2. Flux-gate magnetometer compass for heading information used to reference the current direction to magnetic north, compass range 360°, resolution 0.5°, accuracy 2°, tilt +/- 25° for specified accuracy.

3. Temperature stable quartz oscillator clock, accuracy 12 minutes/year.

4. Optional automatic tilt compensation i.e. the allowable tilt of the meter from the vertical at which the vertical cosine response is fully corrected, angle range +/- 45°, resolution 0.6°, accuracy (speed correction) 1 per cent (angle output) 0.25°.

5. Optional semiconductor (thermistor or platinum) temperature sensor, range -5 to +45 °C, resolution 0.05 °C, accuracy 0.2 °C, response time at 63 per cent 1 min (1.5 sec thermistor or 60msec platinum).

6. Optional conductive conductivity sensor, range 5 to 70mS/cm, resolution 0.1mS/cm, accuracy 0.2mS/cm (optional inductive sensor, range 1 to 70mS/cm).

7. Optional semiconductor strain gauge pressure sensor, range 0 to 1000dBar (70M option), resolution 1dBar (4mm with 70M option), accuracy 0.25 per cent fs.

8. Recorder, CMOS static RAM microprocessor, 64KByte (128K or 256KByte optional) performs vector averaging, burst sampling and adaptive sampling.

Available versions of the S4 are listed in the table below:

Further details are available from the manufacturer's specification sheet.

BODC Current Meter Screening

BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.

Header information is inspected for:

• Irregularities such as unfeasible values
• Inconsistencies between related information. For example:
  • Depths of meter and sea bed.
  • Times for mooring deployment and for start/end of data series.
  • Length of record or number of data cycles, the cycle interval, the clock error and the period over which accrued.
  • Parameters stated as measured and the parameters actually present in the data cycles.
• Originator's comments on meter/mooring performance and data quality.

Documents are written by BODC highlighting irregularities which cannot be resolved.

Data cycles are inspected using time series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non- oceanographic origin may be tagged with the BODC flag denoting suspect value.

The following types of irregularity, each relying on visual detection in the time series plot, are amongst those which may be flagged as suspect:

• Spurious data at the start or end of the record.
• Obvious spikes occurring in periods free from meteorological disturbance.
• A sequence of constant values in consecutive data cycles.

If a large percentage of the data is affected by irregularities, deemed abnormal, then instead of flagging the individual suspect values, a caution may be documented. Likewise documents will highlight irregularities seen in the current vector scatter plots such as incongruous centre holes, evidence of mooring 'knock-down', abnormal asymmetry in tidally dominated records or gaps as when a range of speeds or directions go unregistered due to meter malfunction.

The term 'knock-down' refers to the situation when the 'drag' exerted on a mooring at high current speeds may cause instruments to tilt beyond the angle at which they are intended to operate. At this point the efficiency of the current sensors to accurately record the flow is reduced.

Inconsistencies between the characteristics of the data set and those of its neighbours are sought, and where necessary, documented. This covers inconsistencies in the following:

• Maximum and minimum values of parameters (spikes excluded).
• The orientation and symmetry of the current vector scatter plot.
• The direction of rotation of the current vectors.
• The approximate amplitude and periodicity of the tidal currents.
• The occurrence of meteorological events and, finally, for series for which no time check was possible, the phase.

This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.

BODC Processing

Data were received by BODC in comma separated value ASCII format files. Since the originator files contained several deployment data, BODC split the data per deployment and instrument. Files were renamed with the format: M/year/month/depth(3 digits)/Deployment. For example, M9801040D1.DAT contains data from the mooring from the current meter at 40m depth in January 1998 during the first deployment.

RCM1CURR.DAT was split into 2 files as follows:

• M9801040D1.DAT: from 04/01/1998 12:30:00 to 26/02/1998 11:50:00
• M9802040D2.DAT: from 24/02/1998 01:40:00 to 04/04/1998 09:00:00

RCM2CURR.DAT was split into 2 files as follows:

• M9801140D1.DAT: from 04/01/1998 12:30:00 to 26/02/1998 11:50:00
• M9802140D2.DAT: from 24/02/1998 01:40:00 to 04/04/1998 09:00:00

RCM3CURR.DAT was split into 2 files as follows:

• M9801290D1.DAT: from 04/01/1998 12:30:00 to 26/02/1998 11:50:00
• M9802290D2.DAT: from 24/02/1998 01:40:00 to 04/04/1998 09:00:00

Data of RCM4CURR.DAT from 04/01/1998 12:30:00 to 26/02/1998 11:50:00 were copied to M9801435D1.DAT. Data from the second deployment at 435m depth were provided by the originator but were not transferred because only absent values were present.

These series were reformatted to the internal QXF format using BODC transfer function 420. The following table shows how the variables within the file were mapped to the appropriate BODC parameter codes:

^* The originator did not specify how salinity was calculated.

Project Information

System of Industry Metocean data for the Offshore and Research Communities (SIMORC)

The EU-funded SIMORC project is a collaborative effort between MARIS (Netherlands), BODC (UK), the International Association of Oil and Gas Producers (OGP) and IOC-IODE to provide a harmonised and quality controlled metocean data set from data collected by oil and gas producers, accessible through the SIMORC protocol.

Data Activity or Cruise Information

Data Activity

SIMORC Mooring Myanmar#1

This particular mooring was deployed on 04/01/1998 and was removed on 26/02/1998. It was set from a subsurface mooring on behalf of TOTAL in Myanmar, Block 8 and consisted of the following instruments.

Where MSL = Mean Sea Level

Related Data Activity activities are detailed in Appendix 1

Fixed Station Information

Fixed Station Information

SIMORC: TOTAL Myanmar Fixed Station Document

This site is part of the TOTAL offshore facility and consists of a drilling location in Block M8, offshore Myanmar.

2 moorings consisting of 4 current meters, 2 ADCPs, 1 WLR and 12 temperature recorders were deployed from a subsurface mooring.

The nominal position of the site is 14° 12' 13''N, 94° 09' 37''E. The water depth is 440 m.

Current data were collected by Fugro Geos on behalf of TOTAL from Myanmar Station as follows:

A CTD cast was done before the recovery of the last mooring.

Where

• CM = Current Meter
• ADCP = Acoustic Doppler Current Profiler
• WLR = Water Level Recorder
• HRCD = Hydrography time series at depth

Related Fixed Station activities are detailed in Appendix 2

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Myanmar#1

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Appendix 2: MYANMAR

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.