Metadata Report for BODC Series Reference Number 72458
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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Problem Reports
The salinity data are of unknown accuracy due to problems with the bench salinometer used for analysis of the calibration bottle samples.
Climatological checks indicate accuracy of the order of +/- 0.02 PSU. Noise of this magnitude occurs in the profile, particularly between the surface and 500 dbar.
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
Bissett-Bermann 9040 Conductivity Temperature and Depth
The basic configuration of the B-B 9040 CTD incorporates pressure, temperature and conductivity sensors which could be logged digitally. This system also made it possible to derive other parameters, such as salinity, depth and sound velocity.
The instrument was versatile and it was possible to attach a dissolved oxygen sensor or to change the CTD housing, allowing it to obtain data from deeper layers in the water column. The accuracy for salinity is ±0.02 ppt , and ±0.02°C for temperature.
This instrument was also known as the Plessey 9040.
RRS John Biscoe Cruise 02 CTD Data Documentation
Introduction
Documentation for the CTD data collected on RRS John Biscoe Cruise 02 (27 February - 15 April 1980) by the British Antarctic Survey, Cambridge, U.K., under the direction of R.B. Heywood.
Data Collection
The instrument used was a Plessey 90/40 CTD. Observed parameters were pressure, temperature and conductivity. All sensors were calibrated before and after the cruise. Up to 12 water bottles were mounted on a Rosette sampler and 4 pairs of reversing thermometers were attached. Water bottles were triggered on the downcast at 10m and at the bottom of the cast, the remainder being fired on the upcast (mainly for chemical samples). Data were collected on the downcast.
Calibration
Reversing thermometers were calibrated at the Deacon Laboratory of the Institute of Oceanographic Sciences. The pressure sensor was compared with a Bourdon gauge which had been calibrated at the National Physical Laboratory. The salinities were determined at the British Antarctic Survey using a Guildline Salinometer. Some time after these data were supplied to BODC the salinometer was found to have been faulty. However the original data were no longer recoverable from the original magnetic tapes to be reprocessed, so this version of the data has been retained. The salinities should be treated with great caution. The accuracy of the temperature data is thought to be ±0.01 °C.
Data Processing
Calibrations were applied and derived quantities were computed from algorithms published by Fofonoff and Millard (1983). Data were then averaged into 1 decibar intervals, centred on unit values. BODC has visually inspected the data and flagged spikes in the data as appropriate. However the salinity data from this cruise are very noisy (±0.02 psu), especially between 0 and 500 decibars.
Data Quality
The salinity data from the CTD have been compared with other measurements made in the same region and also with the Levitus Atlas. Deep water values are within 0.01 ppt of other data, for example that collected on Discovery II (1929-1931) and within 0.02 ppt of Levitus Atlas values.
References
Fofonoff, N.P. and Millard Jr., R.C. 1983.
Algorithms for the computation of fundamental properties of sea water. UNESCO Technical Paper on Marine Science 44
Levitus, S. 1982.
Climatological Atlas of the World Ocean. NOAA Professional Paper No. 13. US Government Printing Office. 173pp
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
Cruise Name | JB02 |
Departure Date | 1980-02-27 |
Arrival Date | 1980-04-15 |
Principal Scientist(s) | Barry Heywood (British Antarctic Survey) |
Ship | RRS John Biscoe |
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 |