Metadata Report for BODC Series Reference Number 1029803
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
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Parameters |
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Problem Reports
No Problem Report Found in the Database
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
Nortek Aquadopp Open Water Current Meter
This instrument provides 3D acoustic doppler current measurements along with standard measurements of temperature, pressure, tilt and direction. It can be used in real time measurement situations or can log to an internal recorder powered by internal batteries. It can also be configured to measure surface wave height, period and direction concurrently. It has the unique feature of being run in 'diagnostic' mode when set to collect data at 1 Hz frequency in user specified intervals. This allows studies of mooring motion and the performance of other current meters to be conducted. It can be set in various configurations with titanium housings for deployment at greater depths.
Standard Measured Parameters
- 3D current velocity (East/North/Up, X/Y/Z or Beam 1/2/3)
- Acoustic signal strength (Beam 1/2/3)
- Compass
- Tilt
- Temperature
- Pressure
- Battery voltage
- Status code
- Error code
Surface wave monitoring
The standard Aquadopp is suitable for measuring surface wave height, period, and direction, which are calculated using the PUV method whereby spectra are estimated based on a combination of the pressure signal recorded by the instrument (P) and two horizontal components of the wave orbital velocity (U and V). More specifically, the pressure signal is used to provide an estimate of the wave frequency spectrum. The energy in this spectrum is then used to estimate wave height and period. The measurements of the wave orbital velocities are used to provide an estimate of the wave direction. Since these estimates are based on the distribution of wave energy and are not direct measurements of the free surface, they should be considered inferred estimates.
Both the dynamic pressure and the orbital velocities are driven by surface waves. The signals that are associated with these properties are complicated by the fact that they attenuate (that is the signals are weaker) with depth. The exact behaviour of the attenuation is determined by the water depth and the wavelength being observed. The greater the water depth the greater the attenuation; likewise, the shorter the wavelength (or higher the frequency of the wave) the greater the attenuation for a given water depth. This means that the estimation of wave parameters is limited by both water depth and wave frequency.
Specifications
Water Velocity Measurement | |
---|---|
Range | ± 5 m/s (standard 300 m version) ± 3 m/s (3000 m and 6000 m versions - higher ranges available on request) |
Accuracy | 1% of measured value ± 0.5 cm/s |
Max. sampling rate | 1 Hz, 4 Hz also available on request (standard version) |
Internal sampling rate | 23 Hz |
Measurement Area | |
Measurement cell size | 0.75 m |
Measurement cell position | 0.35 - 5.0 m |
Default position | 0.35 - 1.8 m |
Doppler uncertainty (noise) | |
Typical | 0.5 - 1.0 cm/s |
At 1 Hz sampling rate | 1.5 cm/s |
Echo Intensity | |
Acoustic frequency | 2 MHz |
Resolution | 0.45 dB |
Dynamic range | 90 dB |
Sensors | |
Temperature | Thermistor embedded in head |
Range | -4°C to 40°C |
Accuracy/resolution | 0.1°C / 0.01°C |
Time response | 10 min |
Compass | Magnetometer |
Accuracy/Resolution | 2° / 0.1° for tilt < 20° |
Tilt | Liquid level |
Maximum tilt | 30° |
Up or down | Automatic detect |
Pressure | Piezoresistive |
Range | 0 - 300 m (standard), 0 - 3000 m or 0 - 6000 m |
Accuracy/resolution | 0.5% |
Analogue Inputs | |
No. of channels | 2 |
Voltage supply | 12 V |
Voltage input | 16 bit A/D |
Materials | |
Standard version | Delrin with titanium screws |
3000 m version | Delrin with titanium screws |
6000 m version | Titanium with Delrin transducer head |
Environmental | |
Operating temperature | -4°C to 40°C |
Dimensions | |
Cylinder | 568 mm x 75 mm (standard) 619 mm x 84 mm (3000 m version) 625 mm x 84 mm (6000 m version) |
Weight in air | 3.5 kg (standard) 3.6 kg (3000 m version) 7.6 kg (6000 m version) |
Weight in water | Neutral (standard) 1.2 kg (3000 m version) 4.8 kg (6000 m version) |
Further details can be found in the manufacturer's specification sheets for the Aquadopp, Aquadopp 3000 and Aquadopp 6000.
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 CSV files. They were reformatted to QXF format using BODC transfer function 422. The following table shows how the variables within the files were mapped to the appropriate BODC parameter codes:
Original parameter name | Original Units | Description | BODC Parameter Code | BODC Units | Comments |
---|---|---|---|---|---|
Time | DD-MM-YYYY hh:mm | Date and time (GMT) | AADYAA01 + AAFDZZ01 | Day number and day fraction (GMT) | |
SPEED | cm/s | Speed | LCSAEL01 | cm/sec | |
DIR | degrees True | Direction | LCDAEL01 | degrees True | |
TEMPERATURE | degrees Celsius | Sea temperature | TEMPPR01 | degrees Celsius |
Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO.
Originator's Data Processing
Data processing
Data were exported into ASCII text files from Nortek Aquadopp software, for the following processing:
- The record was truncated to exclude times pre and post deployment.
- Time was recorded in GMT.
- u and v were calculated for each 10 minute sampling period, then converted to speed and direction.
- Depth was derived using an assumed gravity constant of 9.8 m.s-1 and an assumed water density of 1024 kg.m-3
- The attitude data (heading, pitch and roll) were examined and found to be well within the operating limits of -20 ° < Θ < 20 °.
- Checks were then run searching for any outliers in the speed data. The median of 5 values was compared to the centre point, allowing a tolerance of 20cm.s-1. Outliers identified by this automated method were then visually examined and flagged. The same check was run on eastward and northward velocity components. Finally, data were visually examined and any remaining spikes flagged.
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
Start Date (yyyy-mm-dd) | 2008-07-25 |
End Date (yyyy-mm-dd) | 2008-11-22 |
Organization Undertaking Activity | Total S.A. |
Country of Organization | France |
Originator's Data Activity Identifier | Tunu 3 |
Platform Category | subsurface mooring |
SIMORC Mooring Indonesia Tunu 3
The position of the mooring was 0.38799° S; 117.6902° E at a depth of 60 metres.
The mooring was deployed on behalf of TOTAL at Tunu 3, Indonesia and consisted of the following instruments.
Instrument type | Parameters | Deployment start | Deployment end | Comments |
---|---|---|---|---|
Teledyne RDI Workhorse Sentinel ADCP 600 kHz | waves | 25/07/2008 | 21/11/2008 | Approx 15 metres below the sea surface. |
Teledyne RDI Workhorse Sentinel ADCP 300 kHz | waves | 25/07/2008 | 21/11/2008 | Approx 0.5 metres above the seabed |
Nortek Aquadopp current meter | currents | 25/07/2008 | 21/11/2008 | Approx 0.5 metres above sea bed |
RBR Ltd XR420CT | Conductivity, temperature | 25/07/2008 | 21/11/2008 | Approx 15 metres below the surface |
RBR Ltd TG1050 tide gauge | Tides | 25/07/2008 | 21/11/2008 | Approx 0.5 metres above seabed |
Related Data Activity activities are detailed in Appendix 1
Cruise
Cruise Name | Petrogas1 |
Departure Date | 2007-12-14 |
Arrival Date | 2009-03-24 |
Principal Scientist(s) | Alan Kemp (Metocean Services International Ltd. (South Africa office)) |
Ship | Petrogas Supply 1 |
Complete Cruise Metadata Report is available here
Fixed Station Information
Fixed Station Information
Station Name | Indonesia Tunu 3 |
Category | Offshore location |
Latitude | 0° 23.28' S |
Longitude | 117° 41.41' E |
Water depth below MSL | 60.0 m |
SIMORC: TOTAL Indonesia Tunu 3 Fixed Station Document
This site is offshore of the Mahakam Delta, north of Balikpapan in the Makassar Strait. A mooring was deployed at this site.
The nominal position of this site is 0.38799° S; 117.6902° E with an approximate water depth of 60 metres.
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:
Flag | Description |
---|---|
Blank | Unqualified |
< | Below detection limit |
> | In excess of quoted value |
A | Taxonomic flag for affinis (aff.) |
B | Beginning of CTD Down/Up Cast |
C | Taxonomic flag for confer (cf.) |
D | Thermometric depth |
E | End of CTD Down/Up Cast |
G | Non-taxonomic biological characteristic uncertainty |
H | Extrapolated value |
I | Taxonomic flag for single species (sp.) |
K | Improbable value - unknown quality control source |
L | Improbable value - originator's quality control |
M | Improbable value - BODC quality control |
N | Null value |
O | Improbable value - user quality control |
P | Trace/calm |
Q | Indeterminate |
R | Replacement value |
S | Estimated value |
T | Interpolated value |
U | Uncalibrated |
W | Control value |
X | Excessive difference |
SeaDataNet Quality Control Flags
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
Flag | Description |
---|---|
0 | no quality control |
1 | good value |
2 | probably good value |
3 | probably bad value |
4 | bad value |
5 | changed value |
6 | value below detection |
7 | value in excess |
8 | interpolated value |
9 | missing value |
A | value phenomenon uncertain |
B | nominal value |
Q | value below limit of quantification |
Appendix 1: Tunu 3
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.
Series Identifier | Data Category | Start date/time | Start position | Cruise |
---|---|---|---|---|
1050332 | Currents -subsurface Eulerian | 2008-07-25 16:00:00 | 0.38799 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1050320 | Currents -subsurface Eulerian | 2008-07-25 16:10:00 | 0.38799 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1022158 | Waves (statistics) | 2008-07-25 23:00:00 | 0.388 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1030017 | Hydrography time series at depth | 2008-07-26 00:00:00 | 0.38798 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1030226 | Sea surface elevation -unspecified | 2008-07-26 00:00:00 | 0.38798 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1022146 | Waves (statistics) | 2008-07-26 01:00:00 | 0.388 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1030029 | Hydrography time series at depth | 2008-07-26 07:53:00 | 0.38798 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
Appendix 2: Indonesia Tunu 3
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.
Series Identifier | Data Category | Start date/time | Start position | Cruise |
---|---|---|---|---|
1050332 | Currents -subsurface Eulerian | 2008-07-25 16:00:00 | 0.38799 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1050320 | Currents -subsurface Eulerian | 2008-07-25 16:10:00 | 0.38799 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1022158 | Waves (statistics) | 2008-07-25 23:00:00 | 0.388 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1030017 | Hydrography time series at depth | 2008-07-26 00:00:00 | 0.38798 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1030226 | Sea surface elevation -unspecified | 2008-07-26 00:00:00 | 0.38798 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1022146 | Waves (statistics) | 2008-07-26 01:00:00 | 0.388 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |
1030029 | Hydrography time series at depth | 2008-07-26 07:53:00 | 0.38798 S, 117.6902 E | Petrogas Supply 1 Petrogas1 |