Metadata Report for BODC Series Reference Number 641988
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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Time Co-ordinates(UT) |
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Parameters |
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Problem Reports
No Problem Report Found in the Database
Data Access Policy
Open 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.
If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:
"Contains public sector information licensed under the Open Government Licence v1.0."
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.
Data Quality Report: Series 641988
This cast starts at 14m.
James Clark Ross JR06 CTD Data Document
Sampling strategy
A Conductivity-Temperature-Depth (CTD) probe was used to vertically profile the temperature and salinity of the water column. A total of 108 CTD casts were performed during the cruise.
Instrumentation and data processing by originator
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CTD unit and auxiliary sensors
The CTD system used on the JR06 was the MKIII CTD and the RVS CTD level A.
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Sampling device
Salinity samples were taken from all bottles at the beginning and end of the CTD transects. These samples were processed on the Guildline Autosal.
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Data Acquisition and Initial Processing
CTD Data
The majority of the CTD data for Leg 1 and all the data from Leg 2 have been transferred onto the RVS Level 'C' system. The data on the Level 'C' have been calibrated using the 1993 instrument calibrations and the pressure has been corrected for the 3 to 4m offset noted on the deck unit when the CTD was at the water surface. These data have not yet been finally corrected using in situ corrections. In situ temperature has been determined on the CTD casts using digital reversing thermometers. The Level 'C' system was calibrated using the calibration file provided by IOS for the WOCE cruise preceding cruise JR06.
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Problems
While the MKIII CTD performed faultlessly the RVS CTD level A did not. It had a tendency to suddenly stop transmitting data to the Level B which required CTD casts to be restarted on more than one occasion. The new rosette system worked well although there were a few problems the more serious one being the loss of one of the bottle caps which have a tendency to unscrew themselves.
BODC post-processing and screening
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Reformatting
The data were converted from Ascii format into BODC internal format (QXF) to allow use of in-house visualisation tools.
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Screening
Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor SERPLO. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.
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Banking
Once BODC quality control screening was complete, the CTD QXF files were archived in the BODC National Oceanographic Database and the associated metadata were loaded into an ORACLE Relational Database Management System.
Quality control report
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Salinity
The data are erratic with "loops" throughout the downcasts. These have not been flagged but caution should be taken when using the data. Spikes in salinity have been flagged. Data quality reports have been made where casts have started well below the surface as well as where the presence of "looping" is quite extreme and may affect the overall quality of the data.
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Temperature
The data are erratic with "loops" throughout the downcasts. These have not been flagged but caution should be taken when using the data. Spikes in temperature have been flagged. Data quality reports have been made where casts have started well below the surface as well as where the presence of "looping" is quite extreme and may affect the overall quality of the data.
General Data Screening carried out by BODC
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:
- Times for instrument deployment and for start/end of data series
- Length of record and the number of data cycles/cycle interval
- Parameters expected 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 or depth 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 data values will not be altered.
The following types of irregularity, each relying on visual detection in the 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 then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.
Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:
- Maximum and minimum values of parameters (spikes excluded).
- The occurrence of meteorological events.
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.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
Cruise Name | JR19940101 (JR06 Leg 1) |
Departure Date | 1994-01-01 |
Arrival Date | 1994-02-01 |
Principal Scientist(s) | Martin G White (British Antarctic Survey) |
Ship | RRS James Clark Ross |
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 |
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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 |
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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 |