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Metadata Report for BODC Series Reference Number 275919


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 Barry Heywood
Originating Organization British Antarctic Survey
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) BIOMASS
 

Data Identifiers

Originator's Identifier JB05/0198
BODC Series Reference 275919
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1985-01-19 17:55
End Time (yyyy-mm-dd hh:mm) 1985-01-19 20:15
Nominal Cycle Interval 1.0 decibars
 

Spatial Co-ordinates

Latitude 62.24200 S ( 62° 14.5' S )
Longitude 57.53100 W ( 57° 31.9' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor or Sampling Depth 0.99 m
Maximum Sensor or Sampling Depth 1730.87 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
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 -
 

Parameters

BODC CODERankUnitsTitle
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
SSALPR011Parts per thousandSalinity of the water body by conductivity cell
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

The data are derived from instruments that were laboratory calibrated but not recalibrated using in-situ sample data, resulting in data of variable quality.

The data originators believe the temperatures to be reasonable but believe the salinity data to be of a quality too poor to be of value to physical oceanographic studies.

Climatological checks indicate that the accuracy is of the order of 0.1 ppt.


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 05 CTD Data Documentation

Introduction

Documentation for the CTD data collected on RRS John Biscoe Cruise 05 (31 Dec 1984 - 29 Mar 1985) by the British Antarctic Survey, Cambridge, U.K., under the direction of R.B. Heywood.

Data Collection

The instrument used was a Neil Brown Instruments System Mark IIIB CTD. Observed parameters were pressure, temperature and conductivity. All sensors were calibrated before and after the cruise. Up to 12 water bottle calibration bottle samples mounted on a Rosette sampler and 4 pairs of reversing thermometers were attached. Water bottles were triggered on the downcast at 10m and at the bottom of the cast, the remainder being fired on the upcast (mainly for chemical samples). Data were collected on the downcast.

Calibration

Reversing thermometers were calibrated at the Deacon Laboratory of the Institute of Oceanographic Sciences. The pressure sensor was compared with a Bourdon gauge which had been calibrated at the National Physical Laboratory. The accuracy of the temperature data is thought to be ±0.01 °C.

Data Processing

Calibrations were applied and the data despiked by rejecting data values outside of predetermined tolerances. Data values were then averaged to provide data at 1 decibar intervals.

Note that it was not possible to recover and reprocess all of the data collected on this cruise to produce 1 decibar values. For those casts that were not reprocessed an earlier version of the data is held by BODC. Few processing details are available for these casts. Calibrations were applied and the data despiked by rejecting data values outside of predetermined tolerances. Derived quantities were computed from algorithms published by Fofonoff and Millard (1983).

The data were averaged to provide values at the following depths:

  • Every 5m from 5m to 100m
  • Every 100m from 110m to 200m
  • 250m, 260m, 280m, 300m, 325m, 350m, 375m, 400m, 425m, 450m, 500m
  • 600m, 700m, 800m, 900m, 1000m, 1200m, 1500m, 2000m

Salinities from the bottle samples were determined at the British Antarctic Survey using a Guildline Salinometer. Some time after these data were supplied to BODC the salinometer was found to be faulty which casts doubt on the accuracy of the salinity values. The CTD casts that were not reprocessed by BAS and to which these comments apply are as follows:

BODC Series
Reference No.
Originator's
Reference
BODC Series
Reference No.
Originator's
Reference
72747 JB05/0095 72760 JB05/0116
72827 JB05/0181 72888 JB05/0235
72907 JB05/0242 72919 JB05/0252
72920 JB05/0265 72932 JB05/0270
73068 JB05/0395 73148 JB05/0507
73265 JB05/0631 73289 JB05/0658

Data Quality

The deep water salinity data from the CTD have been compared with other measurements made in this region and also with the Levitus Atlas. The data which have not been reprocessed are within less than 0.01 ppt of data collected on various cruises including Discovery II (1929-31) and within about 0.01 ppt of the Levitus Atlas salinities. The reprocessed salinity data are between approximately 0.08ppt lower than the data which has not been reprocessed.

References

Fofonoff, N.P. and Millard Jr., R.C. 1983.
Algorithms for the computation of fundamental properties of sea water. UNESCO Technical Paper on Marine Science 44

Levitus, S. 1982.
Climatological Atlas of the World Ocean. NOAA Professional Paper No. 13. US Government Printing Office. 173pp


Project Information

Biological Investigations of Marine Antarctic Systems and Stocks (BIOMASS)

BIOMASS was a major multi-national scientific programme for the study of the Antarctic marine ecosystem and its living resources, with emphasis on krill (Euphausia superba). It was co-sponsored by the Scientific Committee on Antarctic Research (SCAR) and the Scientific Committee on Oceanic Research (SCOR) in collaboration with the International Association for Biological Oceanography and the Advisory Committee on Marine Resources Research of the Food and Agriculture Organization of the UN.

Data were collected by 20 vessels from 12 countries during 3 field experiments. These were: the First International BIOMASS Experiment (FIBEX), November 1980 to April 1981; the Second International BIOMASS Experiment (SIBEX), Part 1, October 1983 to May 1984 and Part 2, November 1984 to April 1985.

The aim of FIBEX was to carry out a quasi-synoptic survey over a wide area of the South Atlantic, Indian Ocean and Pacific sectors of the Southern Ocean. SIBEX 1 and 2 were designed to produce a temporal sequence of observations focused on much smaller areas of the Bransfield Strait and Prydz Bay regions.

Data were collected on krill distribution from acoustic surveys and krill population structure from net-hauls. Supporting data from ichthyoplankton net-hauls, oceanographic stations (temperature, salinity, nutrients and chlorophyll-a) and observations of sea-birds at sea were also collected.

Data were collated and standardised by the BIOMASS Data Centre, at the British Antarctic Survey, Cambridge, UK. The validation and correction of the data were carried out during data analysis workshops, by the BIOMASS scientists who collected the data. The majority of the BIOMASS data have been utilized during BIOMASS workshops. However, some have not been used and must be regarded as unvalidated. The documentation accompanying the BIOMASS data set lists the known problems and validation status of the data.

At the end of the BIOMASS Programme, the BIOMASS data were made freely available to any researchers. This is on the understanding that due acknowledgement to the BIOMASS Programme and the original data collectors is made in any resulting publications.


Data Activity or Cruise Information

Cruise

Cruise Name JB05
Departure Date 1984-12-31
Arrival Date 1985-03-29
Principal Scientist(s)
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
B nominal value
Q value below limit of quantification