Metadata Report for BODC Series Reference Number 897092
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
Data Description |
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Data Identifiers |
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Time Co-ordinates(UT) |
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Spatial Co-ordinates | |||||||||||||||||||||||||||||
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Parameters |
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Problem Reports
No Problem Report Found in the Database
Data quality report
A scatter plot of the current data reveals an unusual distribution of points, which is roughly triangular in shape. This instrument is located at 1 m depth in a sea loch, so would be strongly influenced by wind-driven currents, and such effects may account for the observations.
Salinity data are noisy and highly variable at times. However, given that the environment in which the instrument was deployed would have been subject to fresh water influx, such noise is not unexpected and no data points have been flagged as suspect.
Data Access Policy
Public domain data
These data have no specific confidentiality restrictions for users. However, users must acknowledge data sources as it is not ethical to publish data without proper attribution. Any publication or other output resulting from usage of the data should include an acknowledgment.
The recommended acknowledgment is
"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."
Narrative Documents
Aanderaa Doppler current sensors 4100, 4100R, 4100A and 4100RA
The Aanderaa 4100 current sensor is a rugged, true vector averaging sensor designed to measure current speed and direction in the ocean. Four transducers transmit short pulses (pings) of acoustic energy along narrow beams and receive the backscattered signals from particles in the water. The Doppler shift of the backscattered signal, coupled with data from the internal compass, allows the instrument to determine the current speed and direction. Current measurements are compensated for tilt by the use of an electrolytic tilt sensor whose accuracy is proportional to the square root of the number of pings in a measuring interval. Temperature is measured using a temperature dependent crystal-oscillator-circuit.
Three additional models are available: 4100R, 4100A and 4100RA. These operate in the same manner as the standard 4100, but there are some differences in specifications, as detailed below:
- 4100R: higher ping rate than 4100; uses RS232 communication instead of SR10; can be configured to output data either automatically or when polled via the RS232 line.
- 4100A: current speed range higher than the 4100.
- 4100RA: current speed range higher than the 4100R.
Other specifications are common to all models.
Specifications
| Acoustic frequency | 2 MHz |
| Beam angle | ± 1° (main lobe) |
| Depth capability | 300 m |
| Operating temperature | -10 to 50°C |
| Ping rate | 4100: 10 pings s-1 in intervals of 2 min or less; 1 ping s-1 in intervals > 2 min 4100R: selectable from 4 to 1200 pings per minute |
| Current Speed | |
| Range | 4100 and 4100R: 0 to 300 cm s-1 4100A and 4100RA: 0 to 500 cm s-1 |
| Resolution | 0.1 % full scale |
| Accuracy | ± 0.15 cm s-1 ± 1 % of reading |
| Standard deviation | 0.55 cm s-1 |
| Current Direction | |
| Range | 0 to 360° magnetic |
| Resolution | 0.35° |
| Accuracy | ± 5° for 0 to 15° tilt ± 7.5° for 15 to 35° tilt |
| Temperature | |
| Range | -10 to 43°C |
| Resolution | 0.05°C |
| Accuracy | ± 0.08°C |
| Tilt circuit | |
| Accuracy | ± 1.5° |
| Compass circuit | |
| Accuracy | ± 3° |
| Sensitivity | 0.01 ppb |
| Typical range | 0.01 to 230 ppb |
Further details can be found in the manufacturer's specification sheet.
BODC Processing
Data were received by BODC in ASCII format files. This series was reformatted to the internal QXF format using BODC transfer function 325. The following table shows how the variables within the file 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:MI | date and time | AADYAA01 and AAFDZZ01 | day number and day fraction GMT | Conversion by transfer |
| u + v | cm/s | Eastward and northward current velocity | LCDAEL01 (direction) and LCSAEL01 (speed) | °, cm/s | Converted by transfer to current direction (Eulerian) in the water column by in-situ current meter and correction to true North, and current speed (Eulerian) in the water column by in-situ current meter |
| T | degrees Celsius | Temperature | TEMPPR01 | degrees Celsius | |
| S | dimensionless | Salinity | PSALPR01 | dimensionless |
Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. Any data considered as suspect were flagged 'M'. Flags from the originator marking suspect data were retained during transfer and flagged 'L'.
Originator's Data Processing
Sampling Strategy
The Aanderaa Doppler Current Sensor deployed in Loch Shieldaig had a sampling frequency of 6 readings per hour. The instrument included temperature and conductivity sensors.
Data Processing
FRS applied the standard manufacturers' calibrations to all current, temperature and salinity data, and produced ASCII files for submission to BODC. Data files were named according to the mooring code (726) and the instrument number (1). The current meter file (7261) contained eastward and northward velocities, and temperature. Corresponding salinity data were provided in a separate file (append s).
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Data Activity
| Start Date (yyyy-mm-dd) | 2006-07-11 |
| End Date (yyyy-mm-dd) | 2006-11-16 |
| Organization Undertaking Activity | Fisheries Research Services Aberdeen Marine Laboratory (now Marine Scotland Aberdeen Marine Laboratory) |
| Country of Organization | United Kingdom |
| Originator's Data Activity Identifier | 726 |
| Platform Category | moored surface buoy |
FRS current meter mooring, Loch Shieldaig
The mooring was located at 57° 32.79' N, 005° 41.23' W in a nominal water depth of 140 m.
The mooring was deployed on 11 July 2006 by Fisheries Research Services (FRS, now known as Marine Scotland Aberdeen Marine Laboratory) on cruise Fram 1206H (10 July 2006-14 July 2006), recovered on 16 November 2006, and consisted of the following instruments.
| Instrument type | Serial Number | Deployment start | Deployment end | Instrument depth (m) | Comments |
|---|---|---|---|---|---|
| Aanderaa Doppler Current Sensor | 89 | 2006-07-11 | 2006-11-16 | 1 |
Cruise
| Cruise Name | 1206H |
| Departure Date | 2006-07-10 |
| Arrival Date | 2006-07-14 |
| Principal Scientist(s) | John Beaton (Fisheries Research Services Aberdeen Marine Laboratory) |
| Ship | Fram |
Complete Cruise Metadata Report is available here
Fixed Station Information
No Fixed Station Information held for the Series
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 |
