Metadata Report for BODC Series Reference Number 87992


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 Institute of Oceanographic Sciences Wormley Laboratory (now National Oceanography Centre, Southampton)
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier 1407
BODC Series Reference 87992
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1975-08-09 08:37
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 5.93000 S ( 5° 55.8' S )
Longitude 44.36000 E ( 44° 21.6' E )
Positional Uncertainty Unspecified
Minimum Sensor Depth 0.0 m
Maximum Sensor Depth 1592.34 m
Minimum Sensor Height -
Maximum Sensor Height -
Sea Floor Depth -
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 -
 

Parameters

BODC CODE Rank Units Short Title Title
PRESPR01 1 Decibars Pres_Z Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
SSALPR01 1 Parts per thousand UspSal Salinity of the water body by conductivity cell
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 Shackleton 7/75 CTD Data Documentation

Introduction

Documentation for CTD data collected on RRS Shackleton Cruise 7/75 (July-August 1975) by the Institute of Oceanographic Sciences Deacon Laboratory, Godalming, Surrey, U.K., under the direction of J. Swallow.

Instrumentation and Protocols

The instrument used was a Neil Brown Instrument Systems CTD which measured pressure, temperature and conductivity. Up to 12 water bottles were put on the wire during the CTD lowering, to provide calibration values and some back-up station data. The output was recorded on magnetic tape and values logged by hand at 100db intervals. Lowering and retrieval rates of 0.5 to 1.5 m/s were employed and the sensors were flushed with distilled water on recovery. The sea water samples were analysed using a Guildline Autolab Salinometer. Reversing thermometers were calibrated before and after the cruise.

Calibration

Pressure

In-situ calibration was possible by comparison between the CTD and the pressure determined from pairs of reversing thermometers (protected and unprotected).

Temperature

In-situ calibration was possible by comparing of the CTD temperatures and reversing thermometers separating the deep and shallow measurements.

Salinity

The salinity data were calibrated using one set of calibration constants for the entire leg of the cruise. These were determined from 10 water samples on each station.

Data Processing

Original values were averaged over an interval of one second and calibration coefficients and correction factors applied. A time constant correction algorithm was employed to compensate for the slower response of the platinum resistance thermometer. Differences between successive values of each parameter were examined; the mean difference and its standard deviation calculated and values greater than several standard deviations from the mean difference were checked. Genuinely suspect data were then replaced by interpolated values. Derived quantities were computed from algorithms published by Fofonoff et al (1974). The data have been averaged to give 1 value approximately every decibar.

References

RRS Shackleton Cruise 7/75, 21 July - 14 August 1975
Current Measurements and Hydrographic Stations between Seychelles, Madagascar and East Africa. Institute of Oceanographic Sciences Cruise Report No. 37. 1975.

Fofonoff, N.P., Hayes, S.P. and Millard Jr., R.C. 1974.
WHOI/Brown CTD microprofiler: methods of calibration and data handling. Woods Hole Oceanographic Institution WHOI-74-89.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name S7/75
Departure Date 1975-07-21
Arrival Date 1975-08-14
Principal Scientist(s)John C Swallow (Institute of Oceanographic Sciences Wormley Laboratory)
Ship RRS Shackleton

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