Metadata Report for BODC Series Reference Number 1215754

• 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

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 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

Further details can be found in the manufacturer's specification sheet.

FRV Scotia 0213S, 0313S, 0513S, 0813S, 0913S, 1113S, 1313S, 1513S, 1613S, and 1713S CTD Instrument Description

Sampling Strategy

CTD casts were carried out during the on FRV Scotia cruises 0213S, 0313S, 0513S, 0813S, 0913S, 1113S, 1313S, 1513S, 1613S, and 1713S using the instrumentation detailed below.

No changes to the CTD instrumentation were recorded during these cruises.

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:

Further details can be found in the manufacturer's specification sheet.

Processing by BODC of FRV Scotia cruises 0213S, 0313S, 0513S, 0813S, 0913S, 1113S, 1313S, 1513S, 1613S, and 1713S CTD data.

The data arrived at BODC in 10 concatenated ASCII format files. Each file represented one of FRV Scotia cruises 0213S (56 casts), 0313S (59 casts), 0513S (102 casts), 0813S (40 casts), 0913S (84 casts), 1113S (15 casts), 1313S (62 casts), 1513S (2 casts), 1613S (25 casts), and 1713S (37 casts).

The concatenated files were sub-divided into individual files for each cast using BODC in house Matlab software, and then reformatted to the internal BODC format.

The following table shows how the variables within the files were mapped to appropriate BODC parameter codes:

* 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.

Processing by Originator of FRV Scotia 1313S CTD data

Sampling Strategy

Marine Scotland performed 62 CTD casts during cruise FRV Scotia 1313S as part of ongoing research funded by the Scottish Government.

The ship set sail on 2 October 2013, journeying from Aberdeen to carry out CTD deployments on the JONSIS long term monitoring section, the Nolso_Flugga section, the Fair Isle- Munken section and the Cape Wrath - Faroe section, all located in the North Sea and North East Atlantic Ocean. The ship returned to dock in Aberdeen on 16 October 2013.

A SBE32 carousal was used to collect all water samples taken during the cruise.

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 and the primary temperature and conductivity channels were adjusted to produce 'edit' channels. Marine Scotland regards the 'edit' channels 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

Marine Scotland used 85 water samples collected by SBE32 carousal to generate a calibration equation as follows:

calibrated conductivity (mS cm^-1) = measured conductivity x 0.999948 + 0.002485

The calibration was not applied to the data by the Originator.

Fluorescence

Marine Scotland used 78 water samples collected by the SBE35 carousel to generate a calibration equation as follows:

Calibrated fluorescence (µg l^-1) = measured fluorescence x 0.00058 + 0.089722.

The calibration was not applied to the data by the Originator.

Reference

Sy A., 1985. An alternative editing technique for oceanographic data. Deep Sea Research, 32 (12), 1591-1599,

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Faroe-Cape Wrath Transect

The Faroe-Cape Wrath transect was started for the THOR (Thermohaline Overturning - at Risk?) project (2007-2013) and has now continued under NACLIM (North Atlantic Climate Variability) project (2012-2017), both projects ran under European Union (EU) Seventh Framework Programme (FP7).

Marine Scotland first sampled the transect in May 2009. Marine Scotland hope to sample this line twice a year (April-May and September-October) and if possible in December.

The stations along this line will be mainly used for CTD deployments although salinity samples will be taken along the line for calibration purposes. Some nutrient samples have been taken by Marine Scotland but it is not anticipated that nutrient sampling will become a regular occurrence.

The Faroese are also sampling this line.

Map of standard stations

Line Stations

Listed below are details of the standard hydrographic stations that form the Faroe-Cape Wrath line.

Faroe - Cape Wrath (extended line)

This line is not shown on the map but may be sampled occasionally.

CTD sampling history

Cruise FRV Scotia 0512S, between 07 May 2012 - 22 May 2012, sampled stations FWZ-01 to FWZ-19 inclusively.

Related Fixed Station activities are detailed in Appendix 1

BODC Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Faroe-Cape Wrath Transect

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

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