Metadata Report for BODC Series Reference Number 1166950
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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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
Quality Control Report
Current speed and direction data, and temperature data where available, appear to be sound. Where salinity values were stable, the signal appears relatively noisy, although noise is low in absolute terms. Salinity spikes beyond the scale of the background noise have been flagged.
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 in ASCII format files. The series were transferred to BODC's in-house format. The following table shows how the variables within the file were mapped to the appropriate BODC parameter codes.
| Original parameter name | Original Units | BODC Parameter Code | BODC Units | Comments |
|---|---|---|---|---|
| Time | DD/MM/YYYY HH:MI (GMT) | AADYAA01, AAFDZZ01 | day number, day fraction | Conversion by transfer |
| Eastward and northward current velocity (u + v) | cm/s | LCDAEL01 (direction) | ° | 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 |
| LCSAEL01 (speed) | cm/s | |||
| Temperature | °C | TEMPPR01 | °C | Where present |
| Salinity | p.p.t. | PSALPR01 | Dimensionless | Where present |
Following reformatting, the data were visually screened. Any data considered suspect were flagged accordingly. The originator's quality control flags were retained during transfer.
Originator's Data Processing
Marine Scotland applied the standard manufacturers' calibrations to all current, temperature and salinity data and produced ASCII files for submission to BODC. Data files (.hmo) were named according to the mooring code and the instrument number. Each current meter file contained eastward and northward velocities and temperature. In cases where the temperature data ran for longer than the current data, the temperature records were saved as separate files appended 't'. Salinity data for each instrument were contained in files appended 's'. Header metadata were collated in additional files (.frm). Speed/Direction distributions (.csd) and harmonic analyses files (.lpr) for the current meter data were also generated.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Data Activity
| Start Date (yyyy-mm-dd) | 2011-04-18 |
| End Date (yyyy-mm-dd) | 2011-07-27 |
| Organization Undertaking Activity | Marine Scotland Aberdeen Marine Laboratory |
| Country of Organization | United Kingdom |
| Originator's Data Activity Identifier | 7991 |
| Platform Category | subsurface mooring |
Marine Scotland mooring (7991), Loch Linnhe
The current meter mooring was located at 56° 43.94' N, 05° 14.99' W in a nominal water depth of 40 m.
The mooring was deployed in Loch Linnhe on 18 April 2011 by Marine Scotland and recovered by the MV Glenmhor on 27 July 2011. Instrumentation details are included in the following table.
| Instrument type | Serial Number | Deployment start | Deployment end | Instrument depth (m) | Comments |
|---|---|---|---|---|---|
| Aanderaa Doppler Current Sensor 4100/4290 | 154 | 18-04-2011 | 27-07-2011 | 1 | - |
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 |
