Metadata Report for BODC Series Reference Number 1746678
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.
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.
Specifications
| 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 |
| Range | 100 m full scale 1.0 m guaranteed minimum 0.8 m typical |
| Range | 1 cm for RS232 output 2.5 cm for analog output |
| Operating depth | 6000 m (PSA 916) or 10000 m (PSA 916T) |
Further details can be found in the manufacturer's specification sheets for the PSA 916 and the PSA 916T.
Instrument Description
CTD Unit and Auxillary Sensors
A Sea-Bird 9plus CTD system used on cruises DY053 and DY054. This was mounted on a 24-way stainless steel rosette frame (serial number SBE CTD8). The CTD was fitted with the following scientific sensors:
| Sensor | Serial Number | Last calibration date | Comments |
|---|---|---|---|
| Sea-Bird 9plus underwater unit | 09P-39607-0803 | - | - |
| Sea-Bird 3P Temperature Sensor (primary) | 03P-4381 | 21st July 2015 | - |
| Sea-Bird 4C Conductivity Sensor (primary) | 04C-3054 | 16th June 2015 | - |
| Digiquartz Temperature Compensated Pressure Sensor | 93896 | 9th July 2014 | - |
| Sea-Bird 3P Temperature Sensor (secondary) | 03P-4712 | 21st July 2015 | - |
| Sea-Bird 4C Conductivity Sensor (secondary) | 04C-3529 | 21st July 2015 | - |
| Sea-Bird 5T Submersible Pump (primary) | 05T-6320 | - | - |
| Sea-Bird 5T Submersible Pump (secondary) | 05T-6916 | - | - |
| Sea-Bird SBE 43 dissolved oxygen sensor | 43-2575 | 31st July 2015 | - |
| Benthos PSAA-916T Altimeter | 59494 | 29th November 2012 | - |
| Chelsea Aquatracka MkIII Fluorometer | 088244 | 6th August 2014 | - |
| WETLabs C-Star Transmissometer | CST-1759TR | 22nd December 2015 | - |
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.
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
The CTD data were supplied to BODC as nine MStar 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 |
|---|---|---|---|---|---|
| scan | - | Scan number | - | - | Not transferred - will be superseded in BODC processing |
| time | - | Time | - | - | Not transferred - will be superseded in BODC processing |
| press | decibars | Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level. | PRESPR01 | decibars | - |
| pressure_temp | degC | - | - | - | Not transferred - not an environmental variable |
| temp | 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. |
| temp1 | degC | - | - | - | Data from primary temperature sensor. Not included in final BODC data set. |
| temp2 | degC | - | - | - | Data from secondary temperature sensor. Not included in final BODC data set. |
| cond | mS/cm | Electrical conductivity of the water body by CTD | CNDCST01 | Siemens per metre | cond divided by 10. The data were chosen as the best of cond1 and cond2 by the originator. |
| cond1 | mS/cm | - | - | - | Data from primary sensor. Not included in final BODC data set. |
| cond2 | mS/cm | - | - | - | Data from secondary sensor. Not included in final BODC data set. |
| altimeter | m | Height above bed in the water body | AHSFZZ01 | m | - |
| 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 |
| fluor | 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 |
| transmittance | % | Transmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer | POPTDR01 | % | - |
| latitude | degrees | - | - | - | Not transferred. Superceded in BODC processing. |
| longitude | degrees | - | - | - | Not transferred. Superceded in BODC processing. |
| psal | 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. |
| psal1 | pss-78 | - | - | - | Data from primary sensor. Not included in final BODC data set. |
| psal2 | pss-78 | - | - | - | Data from secondary sensor. Not included in final BODC data set. |
| depth | m | Depth below surface of the water body by profiling pressure sensor and converted to seawater depth using UNESCO algorithm | DEPHPR01 | m | - |
| potemp | degC | Potential Temperature | - | - | Not transferred - can be calculated from pressure, salinity and temperature |
| potemp1 | degC | Potential Temperature | - | - | Not transferred - can be calculated from pressure, salinity and temperature |
| potemp2 | 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 cruises DY053 and DY054 to produce vertical profiles of the temperature and salinity of the water column.
The CTD data were collected in the Sea-Bird Seasave version 7.23.2 software, and saved. The data were then processed using Sea-Bird software and the mstar software suite (also known as mexec), developed at the National Oceanography Centre (NOC).
The processed data, together with the raw Sea-Bird, configuration and bottle files, were supplied to BODC for banking.
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 | DY054 |
| Departure Date | 2016-07-27 |
| Arrival Date | 2016-08-17 |
| Principal Scientist(s) | N Penny Holliday (National Oceanography Centre, Southampton) |
| Ship | RRS Discovery |
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 |
