Metadata Report for BODC Series Reference Number 1176907
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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Parameters |
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Problem Reports
No Problem Report Found in the Database
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 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.
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.
Alba na Mara CTD Instrument Description
Sampling Strategy
CTD casts were carried out on cruises FRV Alba na Mara 0412A, FRV Alba na Mara 0812A and FRV Alba na Mara 1412A using the instrumentation detailed below.
| Unit | Model | Serial # | Calibration Date (YYYY-MM-DD) |
|---|---|---|---|
| Pressure | Sea-Bird SBE19plus V2 SEACAT | 6029 | 2010-04-29 |
| Temperature | Sea-Bird SBE19plus V2 SEACAT | 6029 | 2010-04-28 |
| Conductivity | Sea-Bird SBE19plus V2 SEACAT | 6029 | 2010-04-30 |
| Fluorometer | Wet Labs ECO FLNTU | 0947 | 2008-03-05 |
No changes to the CTD instrumentation were recorded during these cruises.
BODC CTD Screening
BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.
Header information is inspected for:
- Irregularities such as infeasible values
- Inconsistencies between related information. For example:
- Deepest CTD data cycle is significantly greater than the depth of the sea floor.
- Times of the cruise and the start/end of the data series.
- Length of the record, number of data cycles, cycle interval, clock error and the period over which data were collected.
- Parameters stated as measured and the parameters actually present in the data series.
- Originator's comments on instrument/sampling device performance and data quality.
Documents are written by BODC highlighting irregularities that cannot be resolved.
Data cycles are inspected using depth series plots of all parameters. These presentations undergo screening to detect infeasible values within the data cycles themselves and inconsistencies when comparing adjacent data sets displaced with respect to depth, position or time.
Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value.
The following types of irregularity, each relying on visual detection in the time series plot, are amongst those that may be flagged as suspect:
- Spurious data at the start or end of the record where the instrument was recording in air
- Obvious spikes occurring in the data due electrical problems
- Constant, or near-constant, data channels
If a large percentage of the data is affected by irregularities, deemed abnormal, then instead of flagging the individual suspect values, a caution may be documented.
The following types of inconsistency are detected automatically by software:
- Data points with values outside the expected range for the parameter, as defined by the BODC parameter usage vocabulary.
Inconsistencies between the characteristics of the data set and those of its neighbours are sought, and where necessary, documented. This covers inconsistencies in the following:
- Maximum and minimum values of parameters (spikes excluded).
- Anomalous readings due to the CTD package being bounced through temperature and/or salinity gradients.
This screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC's making are not introduced.
FRV Alba na Mara 1412A CTD Originator's data processing
Sampling Strategy
A total of 43 CTD casts were performed by Marine Scotland as part of on going research funded by the Scottish Government, during cruise FRV Alba Na Mara 1412A. CTD casts were deployed between 20-30 August 2012 in the Wee Bankie, Marr Bank, Berwick's Bank areas off the coast of Edinburgh in the North Sea. A single Knudsen reversing bottle attached to a wire 1 m above the CTD was fired for every cast.
Data Processing
The CTD data were processed by Marine Scotland using the Sea-Bird SeaSoft routines as recommended in the SeaSoft manual for model type Sea-Bird SBE19plus V2 SEACAT. Pressure data were binned to 1 dbar using SeaSoft. The primary temperature and conductivity channels were adjusted to produce 'edit' channels which Marine Scotland regards as the definitive version of the data. The adjustments consisted of a de-spiking process using Marine Scotland in-house visualisation software and, as necessary, application of a low pass filter as described in Sy (1985). The time was recorded in UTC.
Field Calibrations
Conductivity
One water sample was taken for each of the 43 CTD casts deployed to provide calibration for conductivity using the Knudsen reversing bottle mentioned above. These samples (no points discarded) were used by Marine Scotland to generate a calibration equation as follows:
calibrated conductivity (mS cm-1) = measured conductivity x 1.003492 - 0.174913.
The calibration was not applied to the data by the Originator.
Fluorescence
42 water samples were taken for calibration of the fluorescence data using the Knudsen sample bottle as mentioned above. These samples were used by Marine Scotland to generate a calibration equation as follows:
calibrated chlorophyll concentration (µg l-1) = measured fluorescence x 0.637 + 0.006986.
The calibration was not applied to the data by the Originator.
Temperature
Marine Scotland examined the latest and the previous manufacturer's calibrations to look at the differences in the temperature recorded. There were no significant differences and therefore Marine Scotland concluded that no further calibrations needed to be undertaken.
Reference
Sy A., 1985. An alternative editing technique for oceanographic data. Deep Sea Research, 32 (12), 1591-1599,
Processing by BODC of Alba na Mara CTD data
The data arrived at BODC in 3 concatenated ASCII format files representing all 60 of the CTD casts taken during 3 cruises, FRV Alba na Mara 0412A, FRS Alba na Mara 0812A and FRS Alba na Mara 1412A. The CTD casts were split into 60 files, one for each cast, using BODC in house Matlab software. These were reformatted to the internal BODC format using transfer function 340. The following table shows how the variables within the files were mapped to appropriate BODC parameter codes:
| Originator's Variable | Units | Description | BODC Parameter Code | Units | Comment |
|---|---|---|---|---|---|
| Pressure | dbar | Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level | PRESPR01 | dbar | - |
| Temperature (edit) | Centigrade | Temperature of the water body by CTD or STD | TEMPST01 | °C | Celsius = Centigrade |
| Conductivity (edit) | mS cm-1 | Electrical conductivity of the water body by CTD | CNDCST01 | S m-1 | Conversion of Originators units to BODC units: conductivity(edit) * 0.1. BODC applied Originator calibration during transfer |
| Temperature (pri) | Centigrade | Un-adjusted temperature data | N/A | N/A | Primary Temperature. Data were not loaded by BODC as Originator stated Temperature (edit) channel was a quality controlled version of the primary channel. |
| Conductivity (pri) | mS cm-1 | Un-adjusted conductivity data | N/A | N/A | Primary Conductivity. Data were not loaded by BODC as Originator stated Conductivity (edit) channel was a quality controlled version of the primary channel. |
| Temperature (sec) | Centigrade | No data supplied | N/A | N/A | Secondary Temperature |
| Conductivity (sec) | mS cm-1 | No data supplied | N/A | N/A | Secondary Conductivity |
| Fluorescence * | µg l-1 | Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate phase] by in-situ chlorophyll fluorometer. | CPHLPR01 | mg m-3 | FRS Alba Na Mara 0412A and 0812A not calibrated against water samples. |
| 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 calibration against sample data | CPHLPS01 | mg m-3 | FRS Alba Na Mara 1412A calibrated against water samples. BODC applied calibration during transfer. |
| Turbidity | NTU | Turbidity of the water body by in-situ optical backscatter measurement and laboratory calibration against formazin | TURBPR01 | NTU | - |
| - | - | Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm | PSALST01 | Dimensionless | Derived from TEMPST01 and CNDCST01 in transfer using Fofonoff and Millard (1983). |
| - | - | Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm | SIGTPR01 | kg m-3 | Derived from PSALST01, TEMPST01 and PRESPR01 in transfer using Fofonoff and Millard (1983). |
* Originators variable name is Fluorescence but BODC have identified that the data have had manufacturer's calibrations applied and are therefore chlorophyll values.
The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.
Reference
Fofonoff, P., Millard Jr, R.C., 1983. Algorithms for computation of fundamental properties of seawater.Unesco Technical Papers in Marine Sciences 44, 53 pp.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
| Cruise Name | 1412A |
| Departure Date | 2012-08-13 |
| Arrival Date | 2012-09-01 |
| Principal Scientist(s) | Philip Boulcott (Marine Scotland Aberdeen Marine Laboratory) |
| Ship | FRV Alba Na Mara |
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 |
