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Metadata Report for BODC Series Reference Number 667740

Metadata Summary

Data Description

Data Category Hydrography time series at depth
Instrument Type
Sea-Bird SBE 43 Dissolved Oxygen Sensor  dissolved gas sensors
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
Instrument Mounting propelled unmanned submersible
Originating Country United Kingdom
Originator Mr James Perrett
Originating Organization Southampton Oceanography Centre (now National Oceanography Centre, Southampton)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Autosub Under Ice

Data Identifiers

Originator's Identifier ASUB324CTD
BODC Series Reference 667740

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2003-03-25 15:17
End Time (yyyy-mm-dd hh:mm) 2003-03-26 05:12
Nominal Cycle Interval 2.0 seconds

Spatial Co-ordinates

Start Latitude 70.53420 S ( 70° 32.1' S )
End Latitude 70.38010 S ( 70° 22.8' S )
Start Longitude 98.50510 W ( 98° 30.3' W )
End Longitude 98.28270 W ( 98° 17.0' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 0.0 m
Maximum Sensor or Sampling Depth 201.7 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 -


BODC CODERankUnitsTitle
AADYAA011DaysDate (time from 00:00 01/01/1760 to 00:00 UT on day)
AAFDZZ011DaysTime (time between 00:00 UT and timestamp)
ACYCAA011DimensionlessSequence number
ALATGR011DegreesLatitude north relative to WGS84 by dead reckoning based on GPS and em-log or ADCP
ALONGR011DegreesLongitude east relative to WGS84 by dead reckoning based on GPS and em-log or ADCP
DEPHPR011MetresDepth (spatial coordinate) relative to water surface in the water body by profiling pressure sensor and conversion to seawater depth using UNESCO algorithm
DOXYSU011Micromoles per litreConcentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by Sea-Bird SBE 43 sensor and no calibration against sample data
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALCU011DimensionlessPractical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
PSALCU021DimensionlessPractical salinity of the water body by CTD (second sensor) and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
SIGTPR011Kilograms per cubic metreSigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPCU011Degrees CelsiusTemperature of the water body by CTD and NO verification against independent measurements
TEMPCU021Degrees CelsiusTemperature of the water body by CTD (second sensor) and NO verification against independent measurements

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

Sea-Bird Dissolved Oxygen Sensor SBE 43 and SBE 43F

The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.

Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.


Housing Plastic or titanium

0.5 mil- fast response, typical for profile applications

1 mil- slower response, typical for moored applications

Depth rating

600 m (plastic) or 7000 m (titanium)

10500 m titanium housing available on request

Measurement range 120% of surface saturation
Initial accuracy 2% of saturation
Typical stability 0.5% per 1000 h

Further details can be found in the manufacturer's specification sheet.

Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers

The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.

Underwater unit

The CTD underwater unit (SBE 9 or SBE 9 plus) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus, that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.

Temperature, conductivity and pressure sensors

The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.

The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

Additional sensors

Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.

Deck unit or SEARAM

Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus.


Specifications for the SBE 9 plus underwater unit are listed below:

Parameter Range Initial accuracy Resolution at 24 Hz Response time
Temperature -5 to 35°C 0.001°C 0.0002°C 0.065 sec
Conductivity 0 to 7 S m-1 0.0003 S m-1 0.00004 S m-1 0.065 sec (pumped)
Pressure 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) 0.015% of full scale 0.001% of full scale 0.015 sec

Further details can be found in the manufacturer's specification sheet.

JR84 Autosub Mission CTD data

BODC Processing

The data were received by BODC in the ASCII .cnv format used by SeaBird for the storage of CTD data.

Using the SeaBird SeaSoft processing tools, the following operations were carried out:

Align CTD: Values used: Conductivity advance: 0.073 seconds and primary oxygen advance 3 seconds
Cell Thermal Mass: Values used: Primary and Secondary: Alpha = 0.03; Beta = 7
Bin Average: Run using a two second bin
Derive: The following channels were created: depSM: Depth [salt water, m]; sal00: Salinity [PSU]; sal11: Salinity, 2 [PSU]; density00: Density [density, Kg/m^3]; density11: Density, 2 [density, Kg/m^3]; oxsatMg/L: Oxygen Saturation [mg/l]; sigma-é00: Density [sigma-theta, Kg/m^3]; sigma-é11: Density, 2 [sigma-theta, Kg/m^3]
Strip: Stripped first salinity channel and first density channel (as included in originator's files) from the JR84 .CNV files

The data were then transferred to NetCDF using BODC transfer process 357. Following the transfer to NetCDF, the appropriate navigation channels were merged into the file.

BODC Parameter Code Mapping

Raw Data Variable Name Description Units Conversion Factor BODC Parameter Code Units
Date Julian Date month/day/year   AADYAA01 Days since 00:00 01/01/1760
Time UTC hours/minutes/seconds   AAFDZZ01 Fraction of day
  Cycle number     ACYCAA01  
Pos_N Best estimate latitude degrees   ALATGR01 degrees
Pos_E Best estimate longitude degrees   ALONGR01 degrees
depSM Depth in salt water metres   DEPHPR01 metres
sbeox0ML/L Oxygen, SBE 43 milligrams per litre Conversion by transfer DOXYSU01 micromoles per litre
oxsatMg/L  Oxygen Saturation    Calculated by transfer OXYSSC01 Percent
wetBTrans Beam Transmission, Wetlab AC3 Percent   POPTZZ01 Percent
prDM Pressure, Digiquartz decibars   PRESPR01 decibars
sal00 Salinity PSU   PSALCU01  
sal11 Salinity PSU   PSALCU02  
sigma-é00 Density [sigma-theta] kilograms per cubic metre   SIGTPR01 kilograms per cubic metre
sigma-é11 Density [sigma-theta] kilograms per cubic metre   SIGTPR02 kilograms per cubic metre
t090C Temperature [ITS-90] degrees Centigrade   TEMPCU01 degrees Centigrade
t190C Temperature [ITS-90] degrees Centigrade   TEMPCU02 degrees Centigrade

Parameter set rationalisation

Not all of the parameters transferred were suitable for retention in the data series. The transmissometer and fluorometer were not operational and, as the difference between primary and secondary conductivity/temperature pairs was small,only the derived variables associated with the former have been retained.

Data Quality

The data were screened in the BODC EDSERPLO software package in order to check the data quality. The CTD data quality while the platform was at the surface at the beginning and end of each mission was highly varaible in relation to the rest of the series. Consequently, the series were trimmed to include only the sub-surface measurements. Even so, there the quality of the data in some channels at the start of the sereis may still be suspect and some points have been flagged to reflect this.

Autosub Mission 324 CTD data

Data Originator's Comments

On this mission the Autosub was launched outside the ice, programmed to spiral to a holding depth of 100m, run into the ice for 3 miles, perform a grid survey and return to a recovery point. The swath data for this mission were found to be no good, and later a leak was found on a swath system transmitter. Strong currents during this mission were responible for the AUV being 8km east of its programmed track at the end of the mission.

Further details of Autosub operations are avalable in the cruise report.

Project Information

AutoSub Under Ice (AUI) Programme

AutoSub was an interdisciplinary Natural Environment Research Council (NERC) thematic programme conceived to investigate the marine environment of floating ice shelves with a view to advancing the understanding of their role in the climate system.

The AUI programme had the following aims:

  • To attain the programme's scientific objectives through an integrated programme based on interdisciplinary collaborations and an international perspective
  • To develop a data management system for the archiving and collation of data collected by the programme, and to facilitate the eventual exploitation of this record by the community
  • To provide high-quality training to develop national expertise in the use of autonomous vehicles in the collection of data from remote environments and the integration of such tools in wider programmes of research
  • To stimulate and facilitate the parameterising of sub-ice shelf processes in climate models, and to further demonstrate the value of autonomous vehicles as platforms for data collection among the wider oceanographic and polar community

Following the invitation of outline bids and peer review of fully developed proposals, eight research threads were funded as part of AUI:

Physical Oceanography

  • ISOTOPE: Ice Shelf Oceanography: Transports, Oxygen-18 and Physical Exchanges.
  • Evolution and impact of Circumpolar Deep Water on the Antarctic continental shelf.
  • Oceanographic conditions and processes beneath Ronne Ice Shelf (OPRIS).

Glaciology and Sea Ice

  • Autosub investigation of ice sheet boundary conditions beneath Pine Island Glacier.
  • Observations and modelling of coastal polynya and sea ice processes in the Arctic and Antarctic.
  • Sea ice thickness distribution in the Bellingshausen Sea.

Geology and Geophysics

  • Marine geological processes and sediments beneath floating ice shelves in Greenland and Antarctica: investigations using the Autosub AUV.


  • Controls on marine benthic biodiversity and standing stock in ice-covered environments.

The National Oceanography Centre Southampton (NOCS) hosted the AUI programme with ten further institutions collaborating in the project. The project ran from April 2000 until the end of March 2005, with some extensions to projects beyond this date because of research cruise delays. The following cruises were the fieldwork component of the AUI project:

Table 1: Details of the RRS James Clark Ross AUI cruises.

Cruise No. Cruise No. synonyms Dates Areas of study
JR20030218 JR84 28 February 2003 to 4 April 2003 Amundsen Sea, Antarctica
JR20040813 JR106, JR106a, JR106N (North) 10 August 2004 to 30 August 2004 Northeast Greenland Continental Shelf, Greenland
JR20040830 JR106b, JR106S (South) 30 August 2004 to 16 September 2004 Kangerlussuaq Fjord, Greenland
JR20050203 JR97, JR097 3 February 2005 to 11 March 2005 Fimbul Ice Shelf and Weddell Sea, Antarctica . This cruise was redirected from the Filcner-Ronne Ice Shelf to the Fimbul Ice Shelf because of unfavourable sea-ice conditions.

All the cruises utilised the AutoSub autonomous, unmanned and untethered underwater vehicle to collect observations beneath sea-ice and floating ice shelves. AutoSub can be fitted with a range of oceanographic sensors such as:

  • Conductivity Temperature Depth (CTD) instruments
  • Acoustic Doppler Current Profillers (ADCP)
  • A water sampler
  • Swath bathymetry systems
  • Cameras

In addition to use of AutoSub during each cruise measurements were taken from ship. These varied by cruise but included:

  • Ship underway measurements and sampling for parameters such as:
    • Salinity
    • Temperature
    • Fluorescence
    • Oxygen 18 isotope enrichment in water
    • Bathymetry using a swath bathymetry system
  • Full-depth CTD casts for with observations of samples taken for parameters such as:
    • Salinity
    • Temperature
    • Fluorescence
    • Optical transmissivity
    • Dissolved oxygen
    • Oxygen 18 isotope enrichment in water
    • Water CFC content
  • Sea floor photography and video using the WASP system
  • Sea floor sampling with trawls/rock dredges
  • Sea ice observations (ASPeCt), drifters and sampling

The AutoSub project also included numerical modelling work undertaken at University College London, UK.

The project included several firsts including the first along-track observations beneath an ice shelf using an autonomous underwater vehicle. The AutoSub vehicle was developed and enhanced throughout this programme and has now become part of the NERC equipment pool for general use by the scientific community. Further information for each cruise can be found in the respective cruise reports (links in Table 1).

Data Activity or Cruise Information


Cruise Name JR20030218 (JR84)
Departure Date 2003-02-28
Arrival Date 2003-04-04
Principal Scientist(s)Adrian Jenkins (British Antarctic Survey)
Ship RRS James Clark Ross

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