Metadata Report for BODC Series Reference Number 1762494
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 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
A Sea-Bird 9plus CTD system was used on cruise KN221-2. This was mounted on a WHOI made 24-way stainless steel rosette frame (serial number WHOI-01). The CTD was fitted with the following scientific sensors:
| Sensor | Serial Number | Last calibration date | Comments |
|---|---|---|---|
| Sea-Bird 9plus underwater unit | 09P-462 | - | - |
| Sea-Bird 3P Temperature Sensor (primary) | 03P-4195 | 11th October 2013 | Data not submitted to BODC |
| Sea-Bird 4C Conductivity Sensor (primary) | 04C-2147 | 17th October 2013 | Data not submitted to BODC |
| Digiquartz Temperature Compensated Pressure Sensor | 63505 | 15th March 2012 | - |
| Sea-Bird 3P Temperature Sensor (secondary) | 03P-4252 | 10th October 2013 | - |
| Sea-Bird 4C Conductivity Sensor (secondary) | 04C-2768 | 10th October 2013 | - |
| Sea-Bird 5T Submersible Pump (primary) | 05T-2148-3K | - | - |
| Sea-Bird 5T Submersible Pump (secondary) | 05T-3107-3K | - | - |
| Sea-Bird SBE 43 dissolved oxygen sensor | 43-1679 | 23rd October 2013 | - |
| WETLABS ECO-AFL Fluorometer | FLNTURTD-304 | 10th March 2018 | - |
| WETLabs C-Star Transmissometer | CST-1118DR | 31st January 2014 | Data not submitted to BODC |
| WETLabs ECO-NTU Turbidity Meter | FLNTURTD-304 | 10th March 2008 | - |
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 FLNTU fluorescence and turbidity sensor
The Environmental Characterization Optics (ECO) Fluorometer and Turbidity (FLNTU) sensor is a dual wavelength, single-angle instrument that simultaneously determines chlorophyll fluorescence and turbidity. It is easily integrated in CTD packages and provides a reliable turbidity measurement that is not affected by Colored Dissolved Organic Matter (CDOM) concentration.
The FLNTU can operate continuously or periodically and has two different types of connectors to output the data. There are 5 other models that operate the same way as this instrument but have slight differences, as stated below:
- FLNTU(RT) - has an analog an RS-232 serial output and operates continuously, when power is supplied
- FLNTU(RT)D - similar to the FLNTU(RT) but has a depth rating of 6000 m
- FLNTUB - has internal batteries for autonomous operation
- FLNTUS - has an integrated anti-fouling bio-wiper
- FLNTUSB - has the same characteristics as the FLNTUS but with internal batteries for autonomous operation
Specifications
| Temperature range | 0 to 30°C |
| Depth rating | 600 m (standard) 6000 m (deep) |
| Turbidity | |
| Wavelength | 700 nm |
| Sensitivity | 0.01 NTU |
| Typical range | 0.01 to 25 NTU |
| Fluorescence | |
| Wavelength | 470 nm (excitation), 695 nm (emission) |
| Sensitivity | 0.01 µg L-1 |
| Typical range | 0.01 to 50 µg L-1 |
| Linearity | 99% R2 |
Further details can be found in the manufacturer's specification sheet.
BODC Processing
The CTD data were supplied to BODC as 75 Ascii files and converted to the BODC internal format (QXF).
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 |
|---|---|---|---|---|---|
| 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 | degC | Temperature of the water body by CTD or STD | TEMPST01 | degC | The data were chosen as the best of temp1 and temp2 by the originator. |
| Dissolved Oxygen | umol/kg | Concentration of oxygen {O2 CAS 7782-44-7} per unit mass of the water body [dissolved plus reactive particulate phase] | DOXYSC01 | umol/l | Converted from kg to litres |
| - | - | Saturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase] | OXYSZZ01 | % | Calculated by BODC |
| Fluorescence | ug/l | 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/m3 | ug/l=mg/m3 |
| Salinity | pss-78 | Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm | PSALST01 | pss-78 | Calculated from calibrated conductivity measurements. The data were chosen as the best of psal1 or psal2 by the originator. |
| Turbidity | NTU | Turbidity of the water body | TURBXXXX | NTU | - |
| Potential Temp. | degC | Potential Temperature | - | - | Not transferred - can be calculated from pressure, salinity and temperature |
| - | - | Potential temperature of the water body by computation using UNESCO 1983 algorithm | POTMCV01 | degC | Calculated by BODC |
| - | - | Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm | SIGTPR01 | kg/m3 | Calculated by BODC |
| - | - | Conversion factor (volume to mass) for the water body by CTD and computation of density (in-situ potential temperature surface pressure) reciprocal from pressure, temperature and salinity | TOKGPR01 | l/kg | Calculated by BODC |
Following transfer the data were screened using BODC in-house visualisation software. Suspect data values were assigned the appropriate BODC data quality flag. Missing data values, where present, were changed to the missing data value and assigned a BODC data quality flag.
Originator's Data Processing
Sampling strategy
A Conductivity-Temperature-Depth (CTD) unit was used on cruise KN221-2 to produce vertical profiles of the temperature and salinity of the water column. A total of 75 casts were made including one test cast.
Data processing
The data were processed using Sea-Bird software according to SBE data processing guidelines. Raw files were directly logged to a PC from the SBE deck unit using software version Seasave Win 32 V7.21k.
The data were then submitted to BODC for banking as 75 ascii files.
Project Information
UK - Overturning in the Subpolar North Atlantic Programme (UK-OSNAP) Programme
UK-OSNAP is part of an international collaboration to establish a transoceanic observing system in the subpolar North Atlantic. The aim is to quantify and understand the Subpolar Gyre's response to local and remote forcing of mass, heat and freshwater fluxes, within the conceptual framework of the Atlantic Meridional Overturning Circulation (AMOC).
UK-OSNAP is developing a new observing system to provide a continuous record of full-depth, trans-basin mass, heat, and freshwater fluxes. Combining these sustained measurements with innovative modelling techniques will enable the project to characterise the circulation and fluxes of the North Atlantic Subpolar Gyre.
UK-OSNAP is funded by the Natural Environment Research Council (NERC). The project is led by the National Oceanography Centre (NOC) with partners in the University of Liverpool, the University of Oxford and the Scottish Association for Marine Science (SAMS). It is a part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. The project involves fieldwork at sea and model studies.
The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line.
NERC have added an extension to UK-OSNAP, until October 2024. This will result in the UK-OSNAP-Decade: 10 years of observing and understanding the overturning circulation in the subpolar North Atlantic (2014-2024).
Data Activity or Cruise Information
Cruise
| Cruise Name | KN221-2 |
| Departure Date | 2014-07-06 |
| Arrival Date | 2014-08-01 |
| Principal Scientist(s) | William E Johns (Rosenstiel School of Marine and Atmospheric Science) |
| Ship | RV Knorr |
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 |
