Metadata Report for BODC Series Reference Number 1196251


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 Dr Carol Pudsey
Originating Organization British Antarctic Survey
Processing Status QC in progress
Project(s) Marine Geophysics Scotia, Bellingshausen
 

Data Identifiers

Originator's Identifier CTD045_REFORMATTED
BODC Series Reference 1196251
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1990-03-12 05:49
End Time (yyyy-mm-dd hh:mm) 1990-03-12 07:53
Nominal Cycle Interval 1.0 seconds
 

Spatial Co-ordinates

Latitude 60.35333 S ( 60° 21.2' S )
Longitude 37.71167 W ( 37° 42.7' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 1.0 m
Maximum Sensor Depth 3031.0 m
Minimum Sensor Height -38.0 m
Maximum Sensor Height 2992.0 m
Sea Floor Depth 2993.0 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 Unspecified -
 

Parameters

No Parameters for BODC Reference Number = 1196251

 

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

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."


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 John Biscoe cruise JB10 Leg 3 BODC data processing

The files were processed and calibrated at the British Antarctic Survey and were sent to BODC in excel format. The following parameters were sent: pres, sal, temp, sigma-t, ptemp,sigma-th, press/10, sal/10, ptemp/10, but not all were transferred as it was not clear how the originator obtained them.

The data were converted to BODC internal format (QXF) using BODC established procedures. Two parameters were derived during the transfer. The following table shows how the variables within the originator's files were mapped to appropriate BODC parameter codes:

Originator's Parameter Name Units Description BODC Parameter Code Units Comments
press - Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level PRESPR01 dbar -
temp - Temperature of the water body by CTD or STD TEMPST01 °C -
sal - Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements PSALCC01 - -
- - Potential temperature of the water body by computation using UNESCO 1983 algorithm POTCMV01 °C Derived during transfer
- - Sigma-T of the water body by computation from salinity and temperature using UNESCO algorithm SIGTPR01 Kg m -3 Derived during transfer

Reformatted CTD data were visualised using the in-house graphical editor EDSERPLO. Quality control flags were applied to data as necessary.

RRS John Biscoe cruise JB10 Leg 3 CTD originator's data processing

Sampling Strategy

A total of 19 CTD profiles were performed during the cruise. The bottles were fired at different depths throughout the water column. Water samples were also collected for studies on phytoplankton, suspended particulate matter, oxygen isotopes and salinity.

Instrument Descriptions

CTD Unit and Auxiliary Sensors

The CTD unit consisted of a Neil Brown MkIII attached to a carousel with 12 x 2.5 l bottles. The CTD sensors were pressure, conductivity and temperature.

Field Calibrations

The salinity data were calibrated against independent measurements. The calculated CTD salinities were higher than autosal salinities by as much as 0.23 ppt. The independent temperature measurements performed with reversing thermometers showed that the CTD sensor was high by about 0.008 to 0.014°C.


Project Information

Marine Geophysics- Scotia and Bellingshausen

Introduction

Marine geoscience in the Scotia and Bellingshausen Seas was one of the main research interests for British Antarctic Survey (BAS). The investigations were carried out by a group of scientists based at the University of Birmingham, which was absorbed by BAS in the mid- 1980's.

The different survey methods included, amongt others, multichannel and single channel seismic reflection, deeptow boomers, GLORIA (Geological Long Range Inclined Asdic) side-scan sonar and HAWAII-MR1 (HIGP Acoustic Wide_Angle Imaging Instrument) swath bathymetry and side-scan sonar.

This project was funded by BAS and most of the surveys were also carried out by this institution.

Scientific Objectives

This project was carried out in order to gain a better understanding of the Southern Ocean's:

Data Availability

Data sets collected during this project are available to the academic community.


Data Activity or Cruise Information

Cruise

Cruise Name JB10 Leg 3
Departure Date 1990-02-28
Arrival Date 1990-03-23
Principal Scientist(s)Carol J Pudsey (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