Metadata Report for BODC Series Reference Number 294014
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
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
Neil Brown MK3 CTD
The Neil Brown MK3 conductivity-temperature-depth (CTD) profiler consists of an integral unit containing pressure, temperature and conductivity sensors with an optional dissolved oxygen sensor in a pressure-hardened casing. The most widely used variant in the 1980s and 1990s was the MK3B. An upgrade to this, the MK3C, was developed to meet the requirements of the WOCE project.
The MK3C includes a low hysteresis, titanium strain gauge pressure transducer. The transducer temperature is measured separately, allowing correction for the effects of temperature on pressure measurements. The MK3C conductivity cell features a free flow, internal field design that eliminates ducted pumping and is not affected by external metallic objects such as guard cages and external sensors.
Additional optional sensors include pH and a pressure-temperature fluorometer. The instrument is no longer in production, but is supported (repair and calibration) by General Oceanics.
Specifications
These specification apply to the MK3C version.
| Pressure | Temperature | Conductivity | |
| Range | 6500 m 3200 m (optional) | -3 to 32°C | 1 to 6.5 S cm-1 |
| Accuracy | 0.0015% FS 0.03% FS < 1 msec | 0.0005°C 0.003°C < 30 msec | 0.0001 S cm-1 0.0003 S cm-1 < 30 msec |
Further details can be found in the specification sheet.
RRS Challenger Cruise 23/87 CTD Data Documentation
Introduction
Documentation for the CTD data collected on RRS Challenger Cruise 23/87 (8 December 1987 - 21 December 1987) by the School of Ocean Sciences, University College of North Wales, Menai Bridge, U.K., under the direction of A.E. Hill.
Data Collection
The instrument used was a Neil Brown Instruments System Mark III CTD. Observed parameters were pressure, temperature and conductivity. The instrument was lowered as slowly as possible, at about 1 m/s. In general the CTD was lowered to within 5-10 metres of the seabed, except on some slope stations when a rising slope prevented this. The data were logged on a BBC microcomputer.
Calibration
There were some rogue calibration data points. On examination these were found to have been collected in areas of strong temperature or salinity gradients and have been omitted from the statistics.
Temperature
The temperature calibration readings were made using a digital thermometer and standard reversing thermometers. The latter were found to give very different readings from the digital thermometer which gave very good agreement with the CTD sensor.
| Mean temperature difference (digital thermometer - CTD) | 0.000 |
|---|---|
| Standard Deviation | 0.002 |
| Variance | 0.000 |
| No. of Points | 78 |
| Temperature Calibration | CTD temperature + 0.000 (°C) |
Salinity
Water samples for salinity determinations were taken on most casts; on some casts, particularly the deeper ones, more than one calibration sample was taken.
| Mean salinity difference (Water sample - CTD) | 0.0147 |
|---|---|
| Standard Deviation | 0.0081 |
| Variance | 0.0000 |
| No. of points | 140 |
| Salinity Calibration | CTD salinity + 0.0147 (PSU) |
Pressure
There was an offset of 1.7 decibars, i.e.
Pressure = CTD pressure - 1.7 (decibars)
Data Processing
The University's mainframe computer was used for processing the data, using an in-house Pascal CTD package. The data were checked for erroneous readings and the up and downcasts were averaged. The calibration details were applied and the data were processed into 1m depth bins.
Reference
Mitchelson-Jacob, E.G., Hill, A.E. and Simpson, J.H. 1989
A report on the CTD data collected west of Scotland during the winter of 1987-88 as part of the Scottish Coastal Current and Autumnal Circulation Experiment (ACE) programmes. School of Ocean Sciences, University College of North Wales. January 1989.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
| Cruise Name | CH23 |
| Departure Date | 1987-12-08 |
| Arrival Date | 1987-12-21 |
| Principal Scientist(s) | A Edward Hill (University of Wales, Bangor School of Ocean Sciences) |
| Ship | RRS Challenger |
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 |
