Metadata Report for BODC Series Reference Number 667567
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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Time Co-ordinates(UT) |
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Spatial Co-ordinates | |||||||||||||||||||||||||||||||||||||
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Parameters |
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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.
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 Auxillary Sensors
| Sensor | Serial Number | Last calibration date | Comments |
|---|---|---|---|
| Digiquartz Pressure | 82991 | 18th December 2000 | - |
| Temperature SBE-3P | 03P-4051 | 12th January 2001 | - |
| Conductivity SBE-4C | 04C-2537 | 30th January 2001 | - |
| Beckman/YSI dissolved oxygen sensor | 13B-0555 | 6th May 2000 | Used on stations 396-402 |
| Sea-Bird SBE 43 dissolved oxygen sensor | 43-0631 | 31st January 2004 | Used on stations 403-470 |
| Dr. Haardt fluorometer | 14010 | - | Used on stations 404-470 |
| RD Instruments Workhorse monitor 300 KHz | 876 | - | Downward looking/master. Used on stations 404-470 |
| RD Instruments Workhorse monitor 300 KHz | 839 | - | Upward looking/slave. Used on stations 404-470 |
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.
Dr Haardt BackScat 1302 fluorometer
The Dr Haardt BackScat 1302 is a backscatter fluorometer designed to detect concentrations of a variety of substances in the water column. The instrument uses a Xe-flashlight source and exhibits a fast response and low power consumption.
Each BackScat sensor is custom-built to measure substances of interest. The BackScat 1302 comprises three optical sensors integrated into one housing and includes 2 xenon flash tubes and filters for the detection of chlorophyll, yellow substance (gelbstoff) and Mie backscattering.
BODC Processing
The CTD data were supplied to BODC in 73 PStar files and converted BODC's internal format, a netCDF subset.
During transfer the originator's variables were mapped to unique BODC parameter codes. The following table shows the parameter mapping.
| Originator's variable | Units | Description | BODC Code | Units | Comments |
|---|---|---|---|---|---|
| time | - | Time | - | - | Not transferred - will be superseded in BODC processing |
| press | db | Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level. | PRESPR01 | db | - |
| temp | °C | Temperature of the water body by CTD or STD | TEMPST01 | °C | - |
| cond | mS/cm | Electrical conductivity of the water body by CTD | CNDCST01 | S/m | cond divided by 10 |
| salinity | psu | Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm | PSALST01 | Dimensionless | - |
| oxygen | µmol/l | Concentration of oxygen {O2} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ sensor | DOXYZZ01 | Micromoles per litre | - |
| - | - | Saturation of oxygen {O2} in the water body | OXYSSC01 | % | Calculated by the BODC transfer |
| chla | mg/m3 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer | CPHLPR01 | Milligrams per cubic metre | - |
Following transfer the data were screened using BODC in-house visualisation software. Suspect data values were identified during screening and appropriate quality flags were applied. Missing data values were changed to the missing data value and assigned a BODC data quality flag.
Originator's Data Processing
Sampling strategy
In total, 73 CTD stations were completed on cruise PO314 to produce vertical profiles of the temperature and salinity of the water column. Depths of the profiles ranged from 27m to 2685m. In addition to temperature, conductivity and pressure sensors, the last 65 CTDs included sensors for dissolved oxygen and chlorophyll. All CTDs were done at fixed stations along the Extended Ellett Line (EEL) transect between Iceland and Scotland.
Data Acquisition and Initial Processing
The data were processed using PEXEC (pstar) routines. Further details on the processing can be found in the cruise report. The data were calibrated post-cruise.
The processed data, together with the raw Sea-Bird, configuration and bottle files, were supplied to BODC for banking.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
| Cruise Name | PO314 |
| Departure Date | 2004-07-11 |
| Arrival Date | 2004-07-23 |
| Principal Scientist(s) | Jane F Read (Southampton Oceanography Centre) |
| Ship | FS Poseidon |
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 |
