Metadata Report for BODC Series Reference Number 1046843
No Problem Report Found in the Database
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."
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.
Benthos Programmable Sonar Altimeter (PSA) 916 and 916T
The PSA 916 is a submersible altimeter that uses the travel time of an acoustic signal to determine the distance of the instrument from a target surface. It provides the user with high resolution altitude or range data while simultaneously outputting data through a digital serial port. A wide beam angle provides for reliable and accurate range measurements under the most severe operational conditions. The instrument is electronically isolated to eliminate any potential signal interference with host instrument sensors. The PSA 916 is an upgrade of the PSA 900.
The standard model (PSA 916) has an operational depth range of 0 - 6000 m, while the titanium PSA 916T has a depth range of 0 - 10000 m. All other specifications for the two versions are the same.
|Transmit frequency||200 kHz|
|Transmit pulse width||250 µs|
|Beam pattern||14° conical|
|Pulse repetition rate|| |
internal selection: 5 pps
external selection: up to 5 pps- user controlled
100 m full scale
1.0 m guaranteed minimum
0.8 m typical
1 cm for RS232 output
2.5 cm for analog output
|Operating depth||6000 m (PSA 916) or 10000 m (PSA 916T)|
CTD Unit and Auxiliary Sensors
|Sensor||Model||Serial Number||Calibration (UT)||Comments|
|CTD underwater unit||Sea-Bird 9 plus underwater unit||09P-0869||-||-|
|CTD deck unit||Sea-Bird 11 plus underwater unit||11P-0502||-||-|
|24-position carousel||Sonardyne 24-position carousel||234002-001||-||-|
|Pressure transducer||Paroscientific Digiquartz 42K-101||46253||31/07/2009||-|
|Conductivity sensor 1||SBE 4||04C-2450||10/02/2010||-|
|Conductivity sensor 2||SBE 4||04C-2571||29/01/2010||-|
|Temperature sensor 1||SBE 3 plus||03P-2919||13/02/2010||-|
|Temperature sensor 2||SBE 3 plus||03P-4782||12/02/2010||-|
|Dissolved oxygen||SBE 43||43-0619||27/10/2009||Oxygen sensor changed to S/N 43-0242 after cast 68|
|Transmissometer||Chelsea Alphatracka MKII||0971007-001||2010-03-22||-|
|Fluorometer||Chelsea Aquatracka MKIII||088195||2008-05-27||-|
|Altimeter||Benthos PSA-916T 7Hz||874||-||-|
|Light scattering sensor||WetLabs Light scattering sensor||BBRTD-168||-||-|
|Thermometer||SeaBird SBE35 Deep Ocean Standards Thermometer||0005||-||-|
|LADCP||RDI WorkHorse Monitor||13191||-||Downward-looking, LADCP changed to S/N 12369 after cast 20|
|24x 20 litre water samplers||Ocean Test Equipment ES-20L water samplers||01-24||-||-|
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.
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.
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.
The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.
The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.
Further details can be found in the manufacturer's specification sheet.
The data were received in one netcdf file per station and contained data from primary and secondary sensors, with various filtered versions. Most of the uncalibrated filtered data (excluding fluor_filt) were not loaded as they had been superseded by calibrated data. The transmittance and optical backscatter channels were not loaded as these were problematic (see cruise report p.17). The originator derived channels were also not loaded, with potential temperature and sigma-theta re-derived by BODC. In addition, press_filt was not required as press_filt_bin_average was a more appropriate pressure variable to use. The remaining data channels were converted into the internal BODC format.
The reformatted data were visualised using the in-house EDSERPLO software. The data were screened and quality control flags were applied to data as necessary. The conductivity primary sensor 1 was found to have malfunctioned for three of the casts, 27, 38 and 39. This lead to pronounced salinity and density inversions of >0.5 in these profiles. The conductivity from the secondary sensor 2 appeared to be unaffected, whilst sensor 1 and sensor 2 data compared well for the other casts. Therefore, for casts 27, 38 and 39 only sensor 2 data (all variables) have been included and all BODC derived channels have been calculated using sensor 2 data only. The remaining 92 casts have data from the primary sensors only and all derived channels have been calculated from these.
The following table shows how the variables within the netCDF files were mapped to appropriate BODC parameter codes:
|Originator's Parameter Name||Units||Description||BODC Parameter Code||Units||Comments|
|press_filt_bin_average||dbar||Average pressure (rather than bin midpoint).||PRESPR01||dbar||-|
|press_filt||dbar||Pressure exerted by the water column (bin midpoint).||-||-||Not loaded.|
|pressure_temp||°C||Internal temperature measured from CTD pressure sensor.||-||-||Not loaded.|
|scan||number||CTD record number.||-||-||Not loaded.|
|flag||number||Flag channel.||-||-||Not loaded as originator did not use.|
|time||seconds||Time from switching on CTD.||-||-||Not loaded, time taken from header.|
|cond1_filt||mS cm-1||Conductivity from sensor 1, processed, cleaned but uncalibrated.||-||-||Not loaded.|
|cond2_filt||mS cm-1||Conductivity from sensor 2, processed, cleaned but uncalibrated.||-||-||Not loaded.|
|temp1_filt||°C||Temperature from sensor 1, processed, cleaned but uncalibrated.||-||-||Not loaded.|
|temp2_filt||°C||Temperature from sensor 2, processed, cleaned but uncalibrated.||-||-||Not loaded.|
|oxygen_filt||µmol kg-1||Dissolved oxygen concentration, processed, cleaned but uncalibrated.||-||-||Not loaded.|
|altimeter||m||Height above bed from CTD, no processing.||AHSFZZ01||m||-|
|fluor_filt||µg l-1||Concentration of chlorophyll from CTD, no processing or samples available for calibration.||CPHLPM01||mg m-3||-|
|transmittance_filt||Percent||Transmittance, processed, cleaned but uncalibrated.||-||-||Not loaded.|
|backscatter_filt||-||Optical backscatter.||-||-||Not loaded.|
|temp1_cal||°C||Temperature from sensor 1, processed, cleaned and calibrated from SBE35 data.||TEMPCC01||°C||All casts except for 27, 38 and 39. Calibrated against reference thermometer SeaBird SBE35.|
|temp2_cal||°C||Temperature from sensor 2, processed, cleaned and calibrated from SBE35 data.||TEMPCC02||°C||For casts 27, 38 and 39 only. Calibrated against reference thermometer SeaBird SBE35.|
|cond1_cal||mS cm-1||Conductivity from sensor 1, processed, cleaned and calibrated from bottle samples.||CNCLCCI1||S m-1||All casts except for 27, 38 and 39. Converted to siemens per metre by dividing the original by 10.|
|cond2_cal||mS cm-1||Conductivity from sensor 2, processed, cleaned and calibrated from bottle samples.||CNCLCCI2||S m-1||For casts 27, 38 and 39 only. Converted to siemens per metre by dividing the original by 10.|
|oxygen_cal||µmol kg-1||Dissolved oxygen concentration, processed, cleaned and calibrated from bottle samples.||DOXYCZ01||µmol l-1||Converted to micromoles per litre by multiplying the original value by 44.66.|
|psal_cal||pss-78||Practical salinity calculated from calibrated conductivity and temperature data from sensors 1, using the equation of state from UNESCO (1978).||PSALCU01||Dimensionless||All casts except for 27, 38 and 39.|
|psal2_cal||pss-78||Practical salinity calculated from calibrated conductivity and temperature data from sensors 2, using the equation of state from UNESCO (1978).||PSALCU02||Dimensionless||For casts 27, 38 and 39 only.|
|potemp_cal||°C||Potential temperature calculated from calibrated data from primary sensors.||-||-||Not loaded.|
|potemp2_cal||°C||Potential temperature calculated from calibrated data from secondary sensors.||-||-||Not loaded.|
|sigma0_cal||kg m-3||Potential density computed at the surface.||-||-||Not loaded.|
|sigma2_cal||kg m-3||Potential density computed at 2000 dbar.||-||-||Not loaded.|
|sigma4_cal||kg m-3||Potential density computed at 4000 dbar.||-||-||Not loaded.|
|-||-||Sigma-theta.||SIGTPR01||kg m-3||Generated by BODC using the Fofonoff and Millard (1983) algorithm.|
|-||-||Potential temperature.||POTMCV01||°C||Generated by BODC using the Fofonoff and Millard (1983) algorithm.|
|-||-||Oxygen saturation.||OXYSZZ01||Percent||Generated by BODC using the Benson and Krause (1984) algorithm.|
Benson, B.B. and Krause, D., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnology and oceanography, No.29(3), 620-632pp.
Fofonoff, N.P. and Millard, R.C., 1983. Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science, No.44, 53pp.
UNESCO, 1978. Eighth report of the joint panel on oceanographic tables and standards. UNESCO Technical Papers in Marine Science, No.28, 35pp.
Originator's Data Processing
Ninety six CTD profiles were performed during the cruise, 95 were received (cast 5 abandoned as pumped blocked, cast 6 at same location). CTD casts are labelled from 1 to 98. Cast 1 is a test cast, and casts 69, 76 and 81 were cancelled due to time constraints. Data were measured at 24 Hz and averaged to 2 dbar.
Further details of sampling problems and sensor failures can be found in the cruise report.
Bottle samples were drawn for salinity and oxygen from each available bottle depth for every CTD cast. Some bottles were leaking badly and were excluded from any sampling. The bottle depths were chosen from the depths: surface, 25, 50, 75, 100, 150, 200, 300, 400, 600, 800, 1000, (1250), 1500, (1750), 2000, (2250), 2500, (2750), 3000, (3250), 3500, (3750), 4000, (4250), 4500, (4750), 5000, bottom-200, bottom-150, bottom-100, bottom-50, bottom with depths in brackets being dropped (shallowest first) where necessary. On some casts some bottles (especially bottle 20) were double fired, at the expense of another depth, as they were deemed likely to leak. On some casts the bottle depths differed from this scheme due to errors; either deeper depths were dropped in favour of shallower or due to transcription errors.
The following processing steps were taken:
1) Temperature 1 and temperature 2 calibrated from SBE35 thermometer (see section 3c).
2) Bottle conductivity 1 and conductivity 2 back calculated
3) Conductivity calibrations found and applied
4) Salinity recalculated
5) Salinity checked
6) Oxygen calibrated
Conductivity was calibrated rather than salinity using bottle samples from the CTD rosette compared to CTD conductivity. Overall sensor performance was assessed to be good. Bottle sample salinity and CTD salinity were also compared to demonstrate behaviour of sensors. It was concluded that CTD salinity 1 did not have an offset, although temperature 1 did, and so conductivity 1 was calibrated. Salinity 2 had a slight pressure-dependent offset and was therefore calibrated.
The following method provided by Brian King is the standard National Oceanography Centre Southampton scientists' approach for calibrating conductivity;
1) Bottle salinity, as measured by the bench salinometer, is converted to 'potential conductivity' at the CTD bottle location using in situ temperature and pressure, and the CSIRO EOS-80 Seawater algorithms.
2) CTD conductivity is calibrated against this 'potential conductivity'.
3) CTD salinity is derived using the corrected conductivity data and the PSS-78 algorithm.
Temperature data were calibrated using independent temperature values from SBE35 thermometer compared to CTD temperature. Both primary and secondary sensors were calibrated independently.
Oxygen data were calibrated against dissolved oxygen measurements taken from discrete bottles and determined using the Winkler method on board the ship. The CTD oxygen sensor behaviour was observed to have jumped between casts 23 and 26. The sensor was changed after cast 68. See cruise report for further calibration details.
BAS Long Term Monitoring and Survey
The Long Term Monitoring and Survey project (LTMS) has been running since the British Antarctic Survey (BAS) was created. This project is one of the BAS core projects, with several groups of scientists collecting various types of data e.g biological, geological, atmospheric, among others.
Data collection is achievable through a wide scope of instruments and platforms, e.g. the Antarctic research stations, autonomous instrument platforms deployed on or from BAS research ships, BAS aircrafts, satellite remote sensing and others.
This project was implemented in order to measure change and variability in the Earth system. Its long term duration allows for the monitoring of processes that could be missed in shorter term studies and experiments. The data collected is also used to check and improve the reliability of models used to stimulate and predict the behavior of the Earth system.
The main objectives are:
- Topographic survey
- Geosciences survey
- Biological survey and monitoring
- Atmospheric and oceanographic monitoring
The data sets obtained through this project are available to the academic community.
|Cruise Name||JR20100315 (JR235, JR236, JR239)|
|Principal Scientist(s)||Mike Meredith (British Antarctic Survey)|
|Ship||RRS James Clark Ross|
Complete Cruise Metadata Report is available here
Fixed Station Information
|Station Name||WOCE section A23|
WOCE Hydrographic Programme Section A23
This section is part of the One-Time Survey of World Ocean Circulation Experiment (WOCE) designated A23. A hydrographic section from Antarctica to Brazil in the South West Atlantica. A full suite of physical, chemical, biological, meterological and tracer measurements were made. During WOCE in 1995 (James Clark Ross, cruise JR10) the A23 section area encompassed 20-70° S and 20-70° S. Part of this A23 section located in the eastern Scotia Sea has been repeated by the ALBATROSS project (James Clark Ross, cruise JR40) in 1999, the US CLIVAR repeat hydrography/CO2 in 2005 (R/V Ronald H. Brown, cruise A16S_2005a) under the CLIVAR/Carbon repeat hydrography program and by theBritish Antarctic Survey Polar Oceans programme in 2010 (James Ross Clark, cruise JR235).
History of Occupations at Section A23
|Cruise||Date begins||Date ends||Latitude begins||Longitude begins||Latitude ends||Longitude ends||Country||PSO|
|James Clark Ross JR10||20-04-1995||06-06-1995||72° S||16° W||26° S||41° S||UK||K. Heywood|
|James Clark Ross JR40||15-03-1999||22-04-1999||60° S||31° W||55° S||34° W||UK||K. Heywood|
|Ronald H. Brown A16S_2005a||11-01-2005||24-02-2005||60° S||31° W||55° S||35° W||US||R. Wanninkhof|
|James Clark Ross JR235||19-03-2010||24-04-2010||63° S||28° W||60° S||31° W||UK||M. Meredith|
Other Series linked to this Fixed Station for this cruise - 1046591 1046609 1046610 1046622 1046634 1046646 1046658 1046671 1046683 1046695 1046702 1046714 1046726 1046738 1046751 1046763 1046775 1046787 1046799 1046806 1046818 1046831 1046855 1046867 1046879 1046880
Other Cruises linked to this Fixed Station (with the number of series) - JR20100315 (JR235, JR236, JR239) (26)
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
|<||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.)|
|E||End of CTD Down/Up Cast|
|G||Non-taxonomic biological characteristic uncertainty|
|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|
|O||Improbable value - user quality control|