Metadata Report for BODC Series Reference Number 1745835
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags
Metadata Summary
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Problem Reports
No Problem Report Found in the Database
Data Access Policy
Open 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.
If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:
"Contains public sector information licensed under the Open Government Licence v1.0."
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.
Specifications
Housing | Plastic or titanium |
Membrane | 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.
Instrument Description for JR20091212 (JR228) CTD
CTD Unit and Auxiliary Sensors
The CTD unit comprised a Sea-Bird Electronics (SBE) 9plus underwater unit, an SBE 11plus deck unit, a BAS 24-way frame and 24x12 L OTE Water Samplers; all of which were mounted on a stainless steel 24-way CTD frame. Attached to the CTD were two SBE 3P temperature sensors, two SBE 4C conductivity sensors, one Paroscientific Digiquartz pressure sensor, one SBE 43 dissolved oxygen sensor, one CTG Aquatracka MKIII fluorometer and one CTG WETLabs C-Star transmissometer an a Biospherical QCD-905L underwater PAR sensor. An additional independent SBE35 temperature sensor was attached to the frame to perform observations each time a bottle is fired.
Sensor unit | Model | Serial number | Full specification | Calibration dates (YYYY/MM/DD) | Comments |
---|---|---|---|---|---|
CTD underwater unit | SBE 9plus | SBE 9plus | |||
CTD deck unit | SBE 11plus | ||||
Pressure sensor | Paroscientific Digiquartz | 0541-75429 | Paroscientific Digiquartz | 18/07/2007 | |
Temperature sensor | SBE 3P | 5042 | SBE 03P | 12/04/2008 | |
Temperature sensor | SBE 3P | 5043 | SBE 03P | 18/07/2007 | |
Conductivity sensor | SBE 4C | 3488 | SBE 04C | 22/04/2008 | cpcor= -9.57x10-8 |
Conductivity sensor | SBE 4C | 3491 | SBE 04C | 09/04/2008 | cpcor= -9.57x10-8 |
Dissolved oxygen sensor | SBE 43 | 0245 | SBE 43 | 12/06/2007 | |
Irradiance sensor (DWIRR) | Biospherical QCL PAR sensor | 7274 | Biospherical QCP PAR sensor | Measuring downwelling irradiance | |
Fluorometer | Chelsea Aquatracka III | 088-249 | Chelsea MKII Aquatracka | 13/09/2007 | |
Transmissometer | WETLabs C-Star - 25 cm path | CST-527DR | Alphatracka MKII | 14/08/2007 |
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
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.
Chelsea Technologies Group Aquatracka MKIII fluorometer
The Chelsea Technologies Group Aquatracka MKIII is a logarithmic response fluorometer. Filters are available to enable the instrument to measure chlorophyll, rhodamine, fluorescein and turbidity.
It uses a pulsed (5.5 Hz) xenon light source discharging along two signal paths to eliminate variations in the flashlamp intensity. The reference path measures the intensity of the light source whilst the signal path measures the intensity of the light emitted from the specimen under test. The reference signal and the emitted light signals are then applied to a ratiometric circuit. In this circuit, the ratio of returned signal to reference signal is computed and scaled logarithmically to achieve a wide dynamic range. The logarithmic conversion accuracy is maintained at better than one percent of the reading over the full output range of the instrument.
Two variants of the instrument are available, both manufactured in titanium, capable of operating in depths from shallow water down to 2000 m and 6000 m respectively. The optical characteristics of the instrument in its different detection modes are visible below:
Excitation | Chlorophyll a | Rhodamine | Fluorescein | Turbidity |
---|---|---|---|---|
Wavelength (nm) | 430 | 500 | 485 | 440* |
Bandwidth (nm) | 105 | 70 | 22 | 80* |
Emission | Chlorophyll a | Rhodamine | Fluorescein | Turbidity |
Wavelength (nm) | 685 | 590 | 530 | 440* |
Bandwidth (nm) | 30 | 45 | 30 | 80* |
* The wavelengths for the turbidity filters are customer selectable but must be in the range 400 to 700 nm. The same wavelength is used in the excitation path and the emission path.
The instrument measures chlorophyll a, rhodamine and fluorescein with a concentration range of 0.01 µg l-1 to 100 µg l-1. The concentration range for turbidity is 0.01 to 100 FTU (other wavelengths are available on request).
The instrument accuracy is ± 0.02 µg l-1 (or ± 3% of the reading, whichever is greater) for chlorophyll a, rhodamine and fluorescein. The accuracy for turbidity, over a 0 - 10 FTU range, is ± 0.02 FTU (or ± 3% of the reading, whichever is greater).
Further details are available from the Aquatracka MKIII specification sheet.
Biospherical Instruments Log Quantum Cosine Irradiance Sensor QCD-905L
The QCD-905L is a submersible radiometer designed to measure irradiance over Photosynthetically Active Radiation (PAR) wavelengths (400-700 nm). It features a cosine directional response when fully immersed in water.
The sensor is a blue-enhanced high stability silicon photovoltaic detector with dielectric and absorbing glass filter assembly, and produces a logarithmic output. Normal output range is -1 to 6 volts with 1 volt per decade. Typically, the instrument outputs 5 volts for full sunlight and has a minimum output of 0.001% full sunlight, where typical noon solar irradiance is 1.5 to 2 x 1017 quanta cm-2 s-1. The instrument can be calibrated with constants for µE cm-2 s-1 or quanta cm-2 s-1.
The QCD-905L can be coupled to a fixed range data acquisition system like a CTD (Conductivity-Temperature-Depth) profiler or current meter. It has an aluminium and PET housing, and a depth rating of 7000 m.
Specifications
Wavelength | 400 to 700 nm |
Output range | -1 to 6 V, with 1 V decade-1 |
Operating temperature | -2 to 35°C |
Depth range | 0 - 7000 m |
Further details can be found in the manufacturer's manual.
Tritech Digital Precision Altimeter PA200
This altimeter is a sonar ranging device that gives the height above the sea bed when mounted vertically. When mounted in any other attitude the sensor provides a subsea distance. It can be configured to operate on its own or under control from an external unit and can be supplied with simultaneous analogue and digital outputs, allowing them to interface to PC devices, data loggers, telemetry systems and multiplexers.
These instruments can be supplied with different housings, stainless steel, plastic and aluminum, which will limit the depth rating. There are three models available: the PA200-20S, PA200-10L and the PA500-6S, whose transducer options differ slightly.
Specifications
Transducer options | PA200-20S | P200-10L | PA500-6S |
Frequency (kHz) | 200 | 200 | 500 |
Beamwidth (°) | 20 Conical | 10 included conical beam | 6 Conical |
Operating range | 1 to 100 m 0.7 to 50 m | - | 0.3 to 50 m 0.1 to 10 m |
Common specifications are presented below
Digital resolution | 1 mm |
Analogue resolution | 0.25% of range |
Depth rating | 700 , 2000, 4000 and 6800 m |
Operating temperature | -10 to 40°C |
Further details can be found in the manufacturer's specification sheet.
WETLabs C-Star transmissometer
This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.
Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.
This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.
Specifications
Pathlength | 10 or 25 cm |
Wavelength | 370, 470, 530 or 660 nm |
Bandwidth | ~ 20 nm for wavelengths of 470, 530 and 660 nm ~ 10 to 12 nm for a wavelength of 370 nm |
Temperature error | 0.02 % full scale °C-1 |
Temperature range | 0 to 30°C |
Rated depth | 600 m (plastic housing) 6000 m (aluminum housing) |
Further details are available in the manufacturer's specification sheet or user guide.
Originator's processing document for JR20091212 (JR228) CTD data
Sampling strategy
A total of 12 CTD casts were performed during JR20091212 (JR228), which sailed from Rothera (Antarctica) on 12 December 2009 and docked in Stanley (Falkland Islands) on 30 December 2009.
Data Processing
CTD data were collected at 24Hz and logged via the deck unit to a PC running Seasave Win32 version 5.30b (Sea-Bird Electronics, Inc.), which allows real-time viewing of the data. The procedure was to start data logging, deploy the CTD, then stop the instrument at 10m wire out, where the CTD package was left for at least two minutes to allow the seawater-activated pumps to switch on and the sensors to equilibrate with ambient conditions.
The following processing was performed by the Originator using the SBE Data Processing software (Seasave Version 5.30b):
- 1.Data conversion to convert raw data to engineering units
- 2. Align advanced the oxygen data by +5 seconds to ensure that calculations of oxygen are made using measurements from the same parcel of water.
- 3. Wild edit to flag bad data using two passes; the first estimates the standard deviation and the second replaces the appropriate data with badflag
- 4. Cell thermal mass to remove thermal mass effects from measured conductivity using a recursive filter. Alpha was 0.03 and 1/beta was 7.0
- 5. Translate to create output in ascii format to be read in Matlab
The originator then proceeded to process the data further in Matlab using scripts provided by Hugh venables. The procedures included:
- 1. 6. ctdread.m - reads in the SBE file, stores data in Matlab arrays
- 2. offpress.m - replaces any data where the CTD pumps were off with NaNs. There was no pressure offset applied to the data
- 3. editctd.m - manual removal of the 10 m soak prior to the CTD cast, and any data collected at the end of the upcast when the CTD was out of the water. Selected data for all variables is set to NaN. Followed by interactive despiking of the primary and secondary conductivity and temperature; selected data points, plus for the other sensors, are set to NaN
- 4. interpol.m - linearly interpolates to fill data gaps generated by editctd
- 5. salcalapp.m - calculates salinity, potential temperature and sigma-theta, sigma-2 and sigma-4
- 6. splitcast.m - splits the CTD cast into the downcast and upcast
- 7. fallrate.m - removes any data points on the downcast where pressure is less than the previous record or if the fall rate is <0.25 m s-1
- 8. gridctd.m - averages the downcast and upcast data to 2db
- 9. fill_to_surf.m - missing data at the surface is filled with values from the next non-NaN line
-
Field calibrations
No samples were taken for calibration purposes so data remain uncalibrated.
Processing by BODC of RRS James Clark Ross JR20091212 (JR228) CTD data
The files were processed at the British Antarctic Survey and were sent to BODC in matlab and csv formats. The following parameters were sent: time, press, primary and secondary temperature, salinity, conductivity, potemp1, potemp2, sigma0, sigma2 and sigma4, fluorescence, oxygen, par and transmittance but not all were transferred as they were either not relevant, or it was not clear how the originator obtained them.
In addition to the raw CTD data, BODC were provided with the intermediate versions created at by the different processing procedures. The fully processed CTD data binned to 2 dbar downcast bins were then reformatted to BODC's internal NetCDF format. The following table shows the mapping of the originator's variables to the appropriate BODC parameter codes:
Originator's Variable | Units | Description | BODC Parameter Code | Units | Comment |
---|---|---|---|---|---|
press | db | Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level | PRESPR01 | Decibars | - |
temp1 | °C | Temperature of the water body by CTD or STD | TEMPST01 | °C | - |
cond1 | mS cm-1 | Electrical conductivity of the water body by CTD | CNDCST01 | S m-1 | *0.1 |
salin1 | PSU | Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm | PSALST01 | Dimensionless | derived from temp1 and cond1 |
oxy_ml_l | ml l-1 | Concentration of oxygen {O2} per unit volume of the water body [dissolved phase] by Sea-Bird SBE 43 sensor and no calibration against sample data | DOXYSU01 | µ mol l-1 | *44.66 |
fluor_ug_l | µ g l-1 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate phase] by in-situ chlorophyll fluorometer and calibration against sample data | CPHLPS01 | mg m-3 | µ g l-1 = mg m-3 |
trans | % | Transmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer | POPTDR01 | % | |
Potential temperature of the water body by computation using UNESCO 1983 algorithm | POTMCV01 | °C | Derived from TEMPPR01, PSALST01 and PRESPR01 | ||
Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm | SIGTPR01 | kg m-3 | Derived from POTMCV01, PSALST01 and PRESPR01 | ||
Saturation of oxygen {O2} in the water body [dissolved plus reactive particulate phase] | OXYSZZ01 | % | Derived from TEMPPR01, PSALST01 and DOXYSU01 |
Additional variables (secondary temperature, salinity, conductivity, density, potential temperature) are avaiable upon request.
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, and missing data by setting the data to an appropriate value and applying the quality control flag.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
Cruise Name | JR20091211 (JR228) |
Departure Date | 2009-12-11 |
Arrival Date | 2009-12-30 |
Principal Scientist(s) | Jonathan L Watkins (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 |