Metadata Report for BODC Series Reference Number 1060271
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
LI-COR LI-193 Spherical Quantum Sensor
The LI-193 Underwater Spherical Quantum Sensor measures irradiance over the photosynthetically active radiation (PAR) spectral range (400-700 nm). The instrument measures photon flux from all directions, which is often termed photosynthetic photon flux fluence rate (PPFFR) or quantum scalar irradiance. This measurement is particularly important when studying phytoplankton, which utilize radiation from all directions for photosynthesis.
The LI-193 can operate down to 350 m and is fitted with a blue-enhanced silicon photovoltaic detector. Two versions of the instrument are available (193SA and 193SB). These use different connector types for the underwater cable, but the sensors operate in the same manner.
Sensor Specifications
| Absolute Calibration | ± 5 % in air traceable to NBS. |
|---|---|
| Sensitivity | Typically 7 µA per 1000 µmol s-1 m-2 |
| Linearity | Maximum deviation of 1 % up to 10,000 µmol s-1 m-2. |
| Stability | < ± 2 % change over a 1 year period. |
| Response Time | 10 µs. |
| Temperature Dependence | ± 0.15 % per °C maximum. |
| Angular Response | < ± 4% error up to ± 90° from normal axis. |
| Azimuth | < ± 3 % error over 360 ° at 90 ° from normal axis. |
| Detector | High stability silicon photovoltaic detector (blue enhanced). |
| Sensor Housing | Corrosion resistant metal with acrylic diffuser for both saltwater and freshwater applications with an injection moulded, impact resistant, acrylic diffuser. Units have been tested to 500 psi (3400 kPa) (350 meters). |
| Weights | 142 g |
| Cable | Requires 2222UWB Underwater Cable |
Further information can be found in the manufacturer's specification sheet and instruction manual.
RRS Bransfield Cruise AMT6B CTD Instrumentation
Instrumentation
Sea-Bird Electronics SEACAT CTD V3.1 SN2474.
There was no bottle rosette.
Wet Labs WETStar fluorometer, WS3S-297P
Licor LI-193 Quantum Sensor, SPQA.
Wetlabs C-star redlight 25cm pathlength transmissometer
Sea-Bird SBE 19 and SBE 19plus SEACAT Profiler CTDs
The SBE 19 SEACAT Profiler is a self-contained, battery powered, pumped CTD system designed to measure conductivity, temperature, and pressure in marine or fresh water environments to depths of 10,500 meters. It was replaced by the SBE 19plus model in 2001. An updated version of this instrument is the SBE 19plus V2, which incorporates an electronics upgrade and additional features, with six differentially amplified A/D input channels, one RS-232 data input channel, and 64 MB FLASH memory.
The standard CTD unit comes with a plastic housing (rated to 600 m), although this can be replaced by titanium housing for depths up to 7000 m. It is typically used for CTD profiling although a conversion kit is available for mooring deployments. The CTD can also be attached to an SBE 36 CTD Deck Unit and Power/Data Interface Module (PDIM) for real-time operation on single-core armored cable up to 10,000 m.
Specifications
| Parameter | SBE 19 | SBE 19plus |
|---|---|---|
| Temperature | Range: -5 to +35 °C Accuracy: 0.01 °C Resolution: 0.001 °C Calibration: +1 to +32 °C* | Range: -5 to +35 °C Accuracy: 0.005 °C Resolution: 0.0001 °C Calibration: +1 to +32 °C* |
| Conductivity | Range: 0 to 7 S m-1 (0 to 70 mmho cm-1) Accuracy: 0.001 S m-1 Resolution: 0.0001 S m-1 Calibration: 0 to 7 S m-1. Physical calibration over the range 1.4 - 6 S m-1* | Range: 0 to 9 Sm-1 Accuracy: 0.0005 Resolution: 0.00005 (most oceanic waters, resolves 0.4 ppm in salinity); 0.00007 (high salinity waters, resolves 0.4 ppm in salinity); 0.00001 (fresh waters, resolves 0.1 ppm in salinity) Calibration: 0 to 9 S m-1. Physical calibration over the range 1.4 - 6 S m-1* |
| Strain gauge pressure sensor | Range: 0 to100, 150, 300, 500, 1000, 1500, 3000, 5000, 10000 or 15000 psia Accuracy: 0.25% of full scale range (100 - 1500 psia); 0.15% of full scale range (3000 - 15000 psia) Resolution: 0.015% of full scale Calibration: 0 to full scale in 20% steps | Range: 0 to 20, 100, 350, 1000, 2000, 3500 or 7000 m Accuracy: 0.1% of full scale range Resolution: 0.002% of full scale range Calibration: ambient pressure to full scale range in 5 steps |
*Measurements outside this range may be at slightly reduced accuracy due to extrapolation errors.
Options and accessories
Additional sensors can be attached to the CTD, including:
- high accuracy Paroscientific Digiquartz pressure sensor (depth range 0 to 20, 60, 130, 200, 270, 680, 1400, 2000, 4200, 7000 or 10500 m; accuracy 0.02% of full scale; resolution 0.0025% of full scale)
- Dissolved Oxygen (SBE 43 DO Sensor)
- pH* (SBE 18 pH Sensor or SBE 27 pH/ORP Sensor)
- fluorescence
- radiance (PAR)
- light transmission
- optical backscatter (turbidity)
The standard SBE 5M pump may be replaced by an SBE 5P (plastic housing) or 5T (titanium housing) pump for use with dissolved oxygen and/or other pumped sensors. Further details can be found in the manufacturer's SBE 19plus V2 instrument specification or theSBE 19 andSBE 19 plus user guides.
WET Labs WETStar Fluorometers
WET Labs WETStar fluorometers are miniature flow-through fluorometers, designed to measure relative concentrations of chlorophyll, CDOM, uranine, rhodamineWT dye, or phycoerythrin pigment in a sample of water. The sample is pumped through a quartz tube, and excited by a light source tuned to the fluorescence characteristics of the object substance. A photodiode detector measures the portion of the excitation energy that is emitted as fluorescence.
Specifications
By model:
| Chlorophyll WETStar | CDOM WETStar | Uranine WETStar | Rhodamine WETStar | Phycoerythrin WETStar | |
|---|---|---|---|---|---|
| Excitation wavelength | 460 nm | 370 nm | 485 nm | 470 nm | 525 nm |
| Emission wavelength | 695 nm | 460 nm | 530 nm | 590 nm | 575 nm |
| Sensitivity | 0.03 µg l-1 | 0.100 ppb QSD | 1 µg l-1 | - | - |
| Range | 0.03-75 µg l-1 | 0-100 ppb; 0-250 ppb | 0-4000 µg l-1 | - | - |
All models:
| Temperature range | 0-30°C |
|---|---|
| Depth rating | 600 m |
| Response time | 0.17 s analogue; 0.125 s digital |
| Output | 0-5 VDC analogue; 0-4095 counts digital |
Further details can be found in the manufacturer's specification sheet, and in the instrument manual.
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.
RRS Bransfield Cruise AMT6B CTD Processing
Originator's Processing
The CTD profiles were processed onboard using Sea-Bird's data processing software.
Nominal fluorescence was calculated from fluorometer voltage during processing of the raw Sea-Bird files. Manufacturer's calibrations were applied.
PAR was calculated from PAR sensor voltage output during processing of the raw Sea-Bird data files. Manufacturer's calibrations were applied.
Beam attenuation was calculated from transmissometer voltage output during the processing of the raw Sea-Bird files. Manufacturer's calibrations were applied.
BODC data processing
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Reformatting
The data files were sent to BODC in Sea-Bird's data processing software output. All available channels were listed into ASCII format. Non-null channels were then converted to PXF, a BODC internal format. The data were processed from 1Hz averaged down- and upcast data. Sigma-theta was calculated and output from the raw data during the conversion to PXF format.
Parameters
Originator's Parameter Originator's Units Description BODC code BODC Units Comments Pressure decibars Pressure PRESPR01 decibars - Temperature °C Temperature TEMPCU01 °C - Salinity - Salinity PSALCU01 - - chlorophyll concentration mg m-3 Nominal fluorescence CPHLPM01 mg m-3 - Irradiance µE m-2 s-1 Downwelling PAR irradiance IRRDPP01 µE m-2 s-1 Calculated from PAR meter voltage using manufacturer's coefficients Beam attenuation coefficient m-1 Beam attenuation ATTNMS01 m-1 Calibrated to zero in clear water - - Salinity - calibrated PSALCC01 - Calibrated against bottle salinity data - - Calibrated fluorescence CPHLPS01 mg m-3 Calibrated against bottle extracted chl-a data - - Potential temperature POTMCV01 °C Computed using UNESCO POTEMP function - - Sigma-theta SIGTPR01 kg m-3 Computed using UNESCO SVAN function -
Screening
The PXF data were compared with the original data files to ensure that no errors had been introduced during the conversion process. The data channels were then screened on a graphics workstation using in-house visualisation software. This allows multiple channels to be viewed simultaneously. It was obvious from initial screening that the upcast data were of higher quality than the downcast data - this was confirmed by the data originator, Gerald Moore. The start and end-points of the upcast, therefore, were marked. All spurious and null data were flagged with appropriate BODC quality control flags.
The following notes were made during the screening of AMT6B CTD data.
The salinity channel on cast B099S2 was very noisy and has been heavily flagged.There was no upcast for B100S1, so the downcast was screened. Beam attenuation and chlorophyll were both very high above 8m, but these have not been flagged as they could be real data.
For B106S, the beam attenuation signal was very noisy with some high values. The downcast showed fairly constant data, so the upcast data have been flagged as suspect. The salinity channel on this cast was very noisy and has been heavily flagged.
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Loading into the BODC database
After the data had been screened and quality controlled, the data were loaded into the BODC database under the Oracle RDBMS.
The data from all 25 casts were loaded into the data tables.
Calibrations
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Pressure
The pressure sensor had a mean reading of 0.4496 decibar while the CTD was logging in air - this was identified during BODC processing. A pressure correction was, therefore, applied to the data when they were listed from the BODC database.
PRESPR01(corr) = PRESPR01(raw) - 0.4496 decibar (BODC calibration 2563).
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Temperature
No reversing thermometer data are available to check the quality of the temperature data, but the sensor was calibrated before and after the cruise.
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Salinity
There were a number of surface bottle samples that were analysed on the bench salinometer at the time of the CTD cast at each station. These were compared with surface data from the CTD in order to check the quality of the salinity data. One outlier was removed from the population data set. The following relationship has been applied to calibrate the CTD salinity channel.
PSALCC01 = 0.9935 * PSALCU01 + 0.2603 (BODC calibration 2823; r2 = 0.9996; N = 21)
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Fluorometer
The nominal chlorophyll-a data from the CTD were compared with data from HPLC measurements made on bottles taken at the time of the CTD cast at each station. Four outliers were removed from the population data set. The following relationship has been applied to the CTD data.
CPHLPS01 = 0.3096 * CPHLPM01 - 0.0679 (BODC calibration 2843; r2 = 0.9605; N= 23)
This relationship was dominated by sample data points at high chlorophyll-a concentrations. The data at low concentrations showed a high degree of scatter.
Project Information
The Atlantic Meridional Transect (AMT) - Phase 1 (1995-2000)
Who was involved in the project?
The Atlantic Meridional Transect (AMT) programme was designed by and implemented as a collaboration between Plymouth Marine Laboratory (PML) and Southampton Oceanography Centre (SOC). The programme was hosted by Plymouth Marine Laboratory and involved additional researchers from UK and international universities throughout its duration.
What was the project about?
When AMT began in 1995 the programme provided a platform for international scientific collaboration, including the calibration and validation of SeaWiFs measurements and products. The programme provided an exceptional opportunity for nationally and internationally driven collaborative research and provided a platform for excellent multi-disciplinary oceanographic research. As an in situ observation system, the data collected by the AMT consortium informed on changes in biodiversity and function of the Atlantic ecosystem during this period of rapid change to our climate and biosphere.
The scientific aims were to assess:
- mesoscale to basin scale phytoplankton processes
- the functional interpretation of bio-optical signatures
- the seasonal, regional and latitudinal variations in mesozooplankton dynamics
When was the project active?
The first phase of the AMT programme ran from 1995 to 2000 and consisted of a total of 12 cruises. A second phase of funding allowed the project to continue for the period 2002 to 2006 with a further 6 cruises.
Brief summary of the project fieldwork/data
The AMT programme undertook biological, chemical and physical oceanographic research during the annual return passage of the RRS James Clark Ross between the UK and the Falkland Islands or the RRS Discovery between the UK and Cape Town, a distance of up to 13,500 km. This transect crossed a range of ecosystems from sub-polar to tropical and from euphotic shelf seas and upwelling systems to oligotrophic mid-ocean gyres. The transect route was covered north-south in September/October and south-north in April/May of each year.
The measurements of hydrographic and bio-optical properties, plankton community structure and primary production completed on the first 12 transects (1995-2000) represent the most coherent set of repeated biogeochemical observations over ocean basin scales. This unique dataset has led to several important discoveries concerning the identification of oceanic provinces, validation of ocean colour algorithms, distributions of picoplankton, identifying new regional sinks of pCO2 and variability in rates of primary production and respiration.
Who funded the project?
The programme was funded by the Natural Environment Research Council (NERC) and further support was received from the National Aeronautics and Space Administration (NASA) with equipment and funding from the Sea-viewing Wild Field-of-view Sensor (SeaWiFS) project.
Data Activity or Cruise Information
Cruise
| Cruise Name | AMT6b |
| Departure Date | 1998-04-05 |
| Arrival Date | 1998-05-04 |
| Principal Scientist(s) | Gerald Moore (Plymouth Marine Laboratory) |
| Ship | RRS Bransfield |
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 |
