Metadata Report for BODC Series Reference Number 1160930
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 Quality Report for cruise 1611S
Anomalous chlorophyll, oxygen concentration and saturation data were identified and flagged M where aproppriate. Casts with data below 300 m exhibit anomalous attenuance data up to about 500 m. These data have also been flagged M.
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
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
CTD Unit and Auxiliary Sensors
A Sea-Bird Electronics SBE911 plus CTD unit was used. Water samples were collected using a SBE32 carousel. The CTD unit included the following sensors.
| Sensor | Manufacturer | Model | Serial number | Calibration date |
|---|---|---|---|---|
| Pressure | Paroscientific | Digiquartz | 64240 | 2010-08-05 |
| Temperature | Sea-Bird | SBE3 | 2041 and 2105 | 2010-07-22 |
| Conductivity | Sea-Bird | SBE4 | 1615 and 1669 | 2010-07-22 |
| Oxygen | Sea-Bird | SBE43 | 0504 | 2010-08-03 |
| Fluorometer | Wet Labs | ECO_FL | FLRTD-064 | 2003-11-08 |
| Transmissometer | Wet Labs | C-Star | CST-704DR | 2003-08-25 |
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.
WETLabs ECO-FL Fluorometer
The Environmental Characterization Optics series of single channel fluorometers are designed to measure concentrations of natural and synthetic substances in water, and are therefore useful for biological monitoring and dye trace studies. Selected excitation and emission filters allow detection of the following substances: chlorophyll-a, coloured dissolved organic matter (CDOM), uranine (fluorescein), rhodamine, phycoerythrin and phycocyanin.
The ECO-FL can operate continuously or periodically and has two different types of connectors to output the data (analogue and RS-232 serial output). The potted optics block results in long term stability of the instrument and the optional anti-biofouling technology delivers truly long term field measurements.
In addition to the standard model, five variants are available, and the differences between these and the basic ECO-FL are listed below:
- FL(RT): similar to the FL but operates continuously when power is supplied
- FL(RT)D: similar model to the (RT) but has a depth rating of 6000 m
- FLB: includes internal batteries for autonomous operation and periodic sampling
- FLS: similar to FLB but has an integrated anti-fouling bio-wiper
- FLSB: similar to the FLS, but includes internal batteries for autonomous operation
Specifications
| Temperature range | 0 to 30°C |
| Depth rating | 600 m (standard) 6000 m (deep) |
| Linearity | 99 % R2 |
| Chlorophyll-a | |
| Wavelength (excitation/emission) | 470/695 nm |
| Sensitivity | 0.01 µg L-1 |
| Typical range | 0.01 to 125 µg L-1 |
| CDOM | |
| Wavelength (excitation/emission) | 370/460 nm |
| Sensitivity | 0.01 ppb |
| Typical range | 0.09 to 500 ppb |
| Uranine | |
| Wavelength (excitation/emission) | 470/530 nm |
| Sensitivity | 0.07 ppb |
| Typical range | 0.12 to 230 ppb |
| Rhodamine | |
| Wavelength (excitation/emission) | 540/570 nm |
| Sensitivity | 0.01 ppb |
| Typical range | 0.01 to 230 ppb |
| Phycoerythrin | |
| Wavelength (excitation/emission) | 540/570 nm |
| Sensitivity | 0.01 ppb |
| Typical range | 0.01 to 230 ppb |
| Phycocyanin | |
| Wavelength (excitation/emission) | 630/680 nm |
| Sensitivity | 0.15 ppt |
| Typical range | 0.15 to 400 ppt |
Further details can be found in the manufacturer's specification sheet.
Paroscientific Absolute Pressure Transducers Series 3000 and 4000
Paroscientific Series 3000 and 4000 pressure transducers use a Digiquartz pressure sensor to provide high accuracy and precision data. The sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.
The 3000 series of transducers includes one model, the 31K-101, whereas the 4000 series includes several models, listed in the table below. All transducers exhibit repeatability of better than ±0.01% full pressure scale, hysteresis of better than ±0.02% full scale and acceleration sensitivity of ±0.008% full scale /g (three axis average). Pressure resolution is better than 0.0001% and accuracy is typically 0.01% over a broad range of temperatures.
Differences between the models lie in their pressure and operating temperature ranges, as detailed below:
| Model | Max. pressure (psia) | Max. pressure (MPa) | Temperature range (°C) |
|---|---|---|---|
| 31K-101 | 1000 | 6.9 | -54 to 107 |
| 42K-101 | 2000 | 13.8 | 0 to 125 |
| 43K-101 | 3000 | 20.7 | 0 to 125 |
| 46K-101 | 6000 | 41.4 | 0 to 125 |
| 410K-101 | 10000 | 68.9 | 0 to 125 |
| 415K-101 | 15000 | 103 | 0 to 50 |
| 420K-101 | 20000 | 138 | 0 to 50 |
| 430K-101 | 30000 | 207 | 0 to 50 |
| 440K-101 | 40000 | 276 | 0 to 50 |
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.
BODC Processing
Data were received by BODC in one ASCII format file that was subsequently split into 83 separate files, one for each CTD profile. The series were reformatted to the internal QXF format using BODC established procedures. Sample calibrations derived by the data originator were applied to the conductivity data. The following table details mapping of variables to BODC parameter codes.
| Original parameter name | Original Units | Description | BODC Parameter Code | BODC Units | Comments |
|---|---|---|---|---|---|
| Pressure | Decibars | Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level | PRESPR01 | Decibars | |
| Temperature | °C | Temperature of the water body by CTD or STD | TEMPST01 | °C | |
| Conductivity | mS cm-1 | Electrical conductivity of the water body by in-situ conductivity cell and calibration against independent measurements | CNCLCCI1 | S m-1 | Conversion by transfer (mS cm-1 x 0.1). Sample calibrations applied by transfer. |
| Salinity | Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and calibration against independent measurements | PSALCC01 | Dimensionless | Derived by the transfer | |
| Fluorescence | µg l-1 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate phase] by in-situ chlorophyll fluorometer and manufacturer's calibration applied | CPHLPM01 | mg m-3 | |
| Oxygen (ml l-1) | cm-3dm-3 | 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 | DOXYZU01 | µmol l-1 | Conversion by transfer (cm-3dm-3 x 44.66) |
| Saturation of oxygen {O2} in the water body [dissolved phase] | OXYSZZ01 | % | Derived by the transfer | ||
| Beam Attenuation | volts | Attenuance (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer | ATTNMR01 | m-1 |
Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. Any data considered as suspect were flagged. Flags from the originator marking suspect data were retained during transfer.
Originator's Data Processing
Sampling Strategy
A total of 83 CTD casts were performed on FRV Scotia cruise 1611S (11 December 2011 - 23 December 2011) in Faroe-Shetland Channel. The data were collected between 15:11 hours on 11 December 2011 and 13:19 hours on 21 December 2011.
Water samples were collected in order to obtain independent salinity measurements. The sample data were used to derive calibrations for the conductivity profiles collected by the CTD.
Data Processing
The raw CTD data files were processed through the SeaBird Electronics SeaSoft data processing software following standard procedures. The originators used in-house interactive visual display editing software to edit out individual spikes in the primary temperature and conductivity channels. In addition, a low-pass filter (Sy 1985) was applied to particularly noisy data. An ASCII file was generated for each CTD cast and all files from a cruise were concatenated into one ASCII file which was submitted to BODC.
Sy A., 1985. An alternative editing technique for oceanographic data. Deep Sea Research Part A: Oceanographic Research Papers, 32 (12), 1591-1599.
Field Calibrations
Independent salinity samples, obtained from the sample bottles and spread throughout the cruise, were used to calibrate the CTD conductivity data. Outlying points were discarded, and 118 data points were used to derive the calibrations. The sample analyses yielded a straight line conductivity calibration of the form y = mx+c, where m=0.999696 and c = 0.013893.
| Parameter | Value of m (y=mx+c) | Value of c (y=mx+c) | Equation |
|---|---|---|---|
| Conductivity | 0.999696 | 0.013893 | C(cal) = 0.999696C(obs)+0.013893 |
The uncalibrated data and calibrations were submitted to BODC, who applied the appropriate corrections.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
| Cruise Name | 1611S |
| Departure Date | 2011-12-11 |
| Arrival Date | 2011-12-23 |
| Principal Scientist(s) | John Dunn (Marine Scotland Aberdeen Marine Laboratory) |
| Ship | FRV Scotia |
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 |
