Metadata Report for BODC Series Reference Number 1003996


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 Peter Saunders
Originating Organization Institute of Oceanographic Sciences Deacon Laboratory (now National Oceanography Centre, Southampton)
Processing Status banked
Project(s) WOCE
UK WOCE
 

Data Identifiers

Originator's Identifier CTD12274
BODC Series Reference 1003996
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1993-01-06 14:27
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 44.98300 S ( 44° 59.0' S )
Longitude 39.76567 W ( 39° 45.9' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 0.99 m
Maximum Sensor Depth 4974.79 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
DOXYPR01 1 Micromoles per litre WC_dissO2 Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ Beckmann probe
OXYSBB01 1 Percent BKBeck Saturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase] by in-situ Beckmann probe and computation from concentration using Benson and Krause algorithm
POTMCV01 1 Degrees Celsius WC_Potemp Potential temperature of the water body by computation using UNESCO 1983 algorithm
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
PSALST01 1 Dimensionless P_sal_CTD Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm
SIGTPR01 1 Kilograms per cubic metre SigTheta Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO 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 Discovery 199 CTD Data Documentation

Introduction

CTD profile data are presented from the WOCE A11 cruise Discovery 199 as reported by Saunders et al. (1993).

Instrumentation and Methodology

Instrumentation Summary

The CTD profiles were taken with a Neil Brown Systems MkIIIb CTD (Deep01) mounted beneath a bottle rosette. The CTD was fitted with a pressure sensor, conductivity cell, platinum resistance thermometer, a SensorMedic dissolved oxygen sensor, a Sea Tech Inc. 100cm path transmissometer s/n 35, a Simrad altimeter model 807-200m and an IOSDL 10 kHz pinger. No fluorometer was attached to the CTD.

Data Acquisition

Lowering rates for the CTD package were generally in the range 0.5-1.0ms -1 but could be up to 1.5ms -1 . CTD data were logged at 16 frames per second. The CTD deck unit passes raw data to a dedicated Level A microcomputer where 1 second averages are assembled. During this process the Level A calculates the rate of change of temperature and a median sorting routine detects and removes pressure spikes. These data are sent to the Level B for archival. The data are then passed to a Level C workstation for conversion to Pstar format and calibration.

A total of 91 stations were occupied (12247 - 12337).

Data Processing

The 1 second data passed to the Level C were converted to Pstar format and initially calibrated with coefficients from laboratory calibrations followed by a number of calibration corrections. The up cast data were extracted for merging with the bottle firing codes, on time, thus the CTD variables were reconciled with the bottle samples. Final calibrations were applied using the sample bottle data. Finally, down cast data were extracted, sorted on pressure and averaged to 2db values, with any gaps filled by linear interpolation.

The data were worked up to WOCE standards by the data originators before being supplied to BODC.

BODC Data Processing

No further calibrations were applied to the data received by BODC. BODC were mainly concerned with the screening and banking of the data.

The CTD data were received as 2db averaged pressure sorted down cast data. Parameters were pressure (dbar), temperature (°C), salinity (psu), and oxygen (µmol/kg). No transmissometer data were received.

The data were converted into the BODC internal format (PXF) to allow the use of in-house software tools, notably the graphics editor. The oxygen data were converted from µmol/kg to µmol/l.

Spikes in the data were manually flagged 'suspect' by modification of the associated quality control flag. In this way none of the original data values were edited or deleted during quality control. Spikiness was seen in some oxygen profiles at depth and these were flagged suspect. The temperature and salinity profiles for 258-263 exhibited many large instabilities and these have been flagged suspect. For profile 320 the T+S is fairly constant between 80-530db.

Once screened, the CTD data were loaded into a database under the Oracle relational database management system. The start time stored in the database is the CTD deployment time, and the end time is the time the CTD was removed from the water. Actually these times are more precisely the start and end of data logging. Latitude and longitude are the mean positions between the start and end times calculated from the master navigation in the binary merged file.

References

Saunders, P.M. et al. (1993). RRS Discovery Cruise 199. Institute of Oceanographic Sciences Deacon Laboratory, Cruise Report No. 234, 69pp.


Project Information

World Ocean Circulation Experiment (WOCE)

The World Ocean Circulation Experiment (WOCE) was a major international experiment which made measurements and undertook modelling studies of the deep oceans in order to provide a much improved understanding of the role of ocean circulation in changing and ameliorating the Earth's climate.

WOCE had two major goals:


UK WOCE

The UK made a substantial contribution to the international World Ocean Circulation Experiment (WOCE) project by focusing on two important regions:

  1. Southern Ocean - links all the worlds oceans, controlling global climate.
  2. North Atlantic - directly affects the climate of Europe.

A major part of the UK effort was in the Southern Ocean and work included:

In the North Atlantic the UK undertook:

Satellite ocean surface topography, temperature and wind data were merged with in situ observations and models to create a complete description of ocean circulation, eddy motion and the way the ocean is driven by the atmosphere.

The surveys were forerunners to the international Global Ocean Observing System (GOOS). GOOS was later established to monitor annual to decadal changes in ocean circulation and heat storage which are vital in the prediction of climate change.


Data Activity or Cruise Information

Cruise

Cruise Name D199
Departure Date 1992-12-22
Arrival Date 1993-02-01
Principal Scientist(s)Peter M Saunders (Institute of Oceanographic Sciences Deacon Laboratory)
Ship RRS Discovery

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameWOCE Hydrographic Programme Section A11
CategoryOffshore route/traverse

WOCE Hydrographic Programme Section A11

This section is part of the One-Time Survey of World Ocean Circulation Experiment (WOCE) designated A11. A hydrographic section from Chile to South Africa was covered and a full suite of physical, chemical, biological, meteorological and tracer measurements were made.

This section was covered by Discovery cruise D199 and took place from 22 December 1992 to 1 February 1993. The map below shows the geographical coverage of section A11.

BODC image

Other Series linked to this Fixed Station for this cruise - 1003695 1003702 1003714 1003726 1003738 1003751 1003763 1003775 1003787 1003799 1003806 1003818 1003831 1003843 1003855 1003867 1003879 1003880 1003892 1003911 1003923 1003935 1003947 1003959 1003960 1003972 1003984 1004011 1004023 1004035 1004047 1004059 1004060 1004072 1004084 1004096 1004103 1004115 1004127 1004139 1004140 1004152 1004164 1004176 1004188 1004207 1004219 1004220 1004232 1004244 1004256 1004268 1004281 1004293 1004300 1004312 1004324 1004336 1004348 1004361 1004373 1004385 1004397 1004404 1004416 1004428 1004441 1004453 1004465 1004477 1004489 1004490 1004508 1004521 1004533 1004545 1004557 1004569 1004570 1004582 1004594 1004601 1004613 1004625 1004637 1004649 1004650 1004662 1004674 1004686


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