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Metadata Report for BODC Series Reference Number 490261

Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
Neil Brown MK3 CTD  CTD; water temperature sensor; salinity sensor; dissolved gas sensors
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization University of Wales, Bangor School of Ocean Sciences (now Bangor University School of Ocean Sciences)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) -

Data Identifiers

Originator's Identifier PM3/95/F2
BODC Series Reference 490261

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1995-06-21 23:08
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 decibars

Spatial Co-ordinates

Latitude 53.66700 N ( 53° 40.0' N )
Longitude 5.83300 W ( 5° 50.0' W )
Positional Uncertainty Unspecified
Minimum Sensor or Sampling Depth 1.5 m
Maximum Sensor or Sampling Depth 59.0 m
Minimum Sensor or Sampling Height 7.0 m
Maximum Sensor or Sampling Height 64.5 m
Sea Floor Depth 66.0 m
Sea Floor Depth Source -
Sensor or Sampling Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface


BODC CODERankUnitsTitle
ACYCAA011DimensionlessSequence number
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALPR011DimensionlessPractical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPST011Degrees CelsiusTemperature of the water body by CTD or STD

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

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.


These specification apply to the MK3C version.

Pressure Temperature Conductivity

6500 m

3200 m (optional)

-3 to 32°C 1 to 6.5 S cm-1

0.0015% FS

0.03% FS < 1 msec


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.

RV Prince Madog Cruise PM3/95 CTD Data Documentation


Documentation for the CTD data from a series of cruises in the western Irish Sea carried out by University of Wales, Bangor during 1995 on the RV Prince Madog under the direction of Dr A.E. Hill. The work was supported by NERC grant GR3/9601, "Seasonal Gyres in Shelf Seas".

The data are already calibrated. Coefficients and method are given below. Density has been derived using the formulation recommended in Unesco Tech. reports 36,38,40 (1981).


Neil Brown Instruments System Mark III CTD In all cases, observed parameters were pressure, temperature and conductivity.

Sampling Protocols

The typical instrument descent rate was 1 m/s. Data were logged on an IBM compatible PC.

Data from the Neil Brown was collected with EG&G CTD data acquisition module Version 2.02.

Data Processing

Data from the Neil Brown were processed with EG&G Post Processing module Version 1.22

In all cases, data were checked for rogue values and averaged into 1m depth bins. Calibration coefficients were subsequently applied using an in-house program which created the files sent here.


Temperature was calibrated using standard reversing thermometers (0.001 °C accuracy) and salinity samples from a rosette. Salinity samples were measured with Autosal Model 8400A. Samples were collected from well mixed regions of the water column to ensure good calibration.


The temperature calibration was calculated as a difference:

Temperature = CTD temperature + dT (°C)


Salinity calibration was calculated as a ratio:

Salinity = CTD salinity / Sr Cruise PM3_95

Number of samples 13
Mean dT 0.018
Standard deviation dT 0.005
Mean Sr 1.009
Standard deviation Sr 0.0003

Project Information

No Project Information held for the Series

Data Activity or Cruise Information


Cruise Name PM3/95
Departure Date 1995-06-20
Arrival Date 1995-06-22
Principal Scientist(s)
Ship Prince Madog

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