Metadata Report for BODC Series Reference Number 295982


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
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
Project(s) -
 

Data Identifiers

Originator's Identifier CH24/K910
BODC Series Reference 295982
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1988-02-14 23:30
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 metres
 

Spatial Co-ordinates

Latitude 57.92170 N ( 57° 55.3' N )
Longitude 9.17670 W ( 9° 10.6' W )
Positional Uncertainty Unspecified
Minimum Sensor Depth 1.0 m
Maximum Sensor Depth 169.0 m
Minimum Sensor Height 11.0 m
Maximum Sensor Height 179.0 m
Sea Floor Depth 180.0 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor 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
 

Parameters

BODC CODE Rank Units Short Title Title
CNDCPR01 1 Siemens per metre InSituCond Electrical conductivity of the water body by in-situ conductivity cell
DEPHPR01 1 Metres CmpDep Depth below surface of the water body by profiling pressure sensor and converted to seawater depth using UNESCO algorithm
PSALPR01 1 Dimensionless P_sal Practical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPST01 1 Degrees Celsius WC_temp_CTD Temperature 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.

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 24/88 CTD Data Documentation

Introduction

Documentation for the CTD data collected on RRS Challenger Cruise 24/88 (3 December 1988 - 15 December 1988) by the School of Ocean Sciences, University College of North Wales, Menai Bridge, U.K., under the direction of J.H. Simpson.

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 digital thermometers (RMT4002). These gave very good agreement with the CTD sensor.

Mean temperature difference
(digital thermometer - CTD)
0.000
Standard Deviation 0.003
Variance 0.000
No. of Points 60
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)
0.0168
Standard Deviation 0.0036
Variance 0.0000
No. of Points 135
Salinity Calibration CTD salinity + 0.0168 (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 CH24
Departure Date 1988-02-03
Arrival Date 1988-02-15
Principal Scientist(s)John H Simpson (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