Metadata Report for BODC Series Reference Number 385208

• 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

The oxygen data collected on this cruise have not been calibrated against sample data and should be used with great caution.

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 Electronics SBE13 Dissolved Oxygen Sensor

The SBE 13 was designed as an auxiliary sensor for Sea Bird SBE 9plus, but can fitted in custom instrumentation applications. When used with the SBE 9 Underwater Unit, a flow-through plenum improves the data quality, as the pumping water over the sensor membrane reduces the errors caused by oxygen depletion during the periods of slow or intermittent flushing and also reduces exposure to biofouling.

The output voltage is proportional to membrane current (oxygen current) and to the sensor element's membrane temperature (oxygen temperature), which is used for internal temperature compensation.

Two versions of the SBE 13 are available: the SBE 13Y uses a YSI polarographic element with replaceable membranes to provide in situ measurements up to 2000 m depth and the SBE 13B uses a Beckman polarographic element to provide in situ measurements up to 10500 m depth, depending on the sensor casing. This sensor includes a replaceable sealed electrolyte membrane cartridge.

The SBE 13 instrument has been out of production since 2001 and has been superseded by the SBE 43.

Specifications

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

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.

RRS Challenger Cruise 89/92 CTD Data Documentation

Introduction

Documentation for the CTD data collected on RRS Challenger 89/92 (February - March 1992) by the Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland, UK, under the direction of D. J. Ellett.

Instrumentation and Processing

The instrument used was a Seabird 9/11 CTD, and the data were processed using the Seabird software. The manufacturer's calibrations were used. Data have been averaged to 1 decibar values.

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

DML Station HE1

Station HE1 is one of five fixed CTD stations heading south to south-west from Loch Bracadale (Isle of Skye, Scotland) into the Sea of the Hebrides. The station was established by scientists at Dunstaffnage Marine Laboratory (DML).

Related Fixed Station activities are detailed in Appendix 1

Fixed Station Information

DML Sea of the Hebrides STD/CTD Sections

The Sea of the Hebrides lies between the southernmost islands of the Outer Hebrides and, to the east, the northern Inner Hebridean islands and Scottish mainland. This area of the shelf has been surveyed since the mid 1970s by numerous research and government institutes. The region contains many repeated hydrographic stations, which collectively form transects. These repeated survey transects form part of a greater network of similar sections on the western Scottish continental shelf, which were established by Dunstaffnage Marine Laboratory (DML).

Map of standard Sea of the Hebrides STD/CTD Stations

Map produced using the GEBCO Digital Atlas.

The triangles and squares indicate the nominal positions of individual Line HD and HE stations respectively. Measurements made at repeated Sea of the Hebrides STD/CTD stations lie within a box bounded by co-ordinates 56.6° N, 7.664° W at the south west corner and 57.313° N, 5.933° W at the north east corner.

Several repeated hydrographic stations on the Ellett Line/Extended Ellett Line occupy the southern area of the Sea of the Hebrides. Further information about these survey transects are summarised here.

Nominal station details:

DML Line HD: Loch Boisdale (South Uist, Scotland) - Loch Moidart (mainland Scotland)

DML Line HE: Loch Bracadale (Skye, Scotland) - north west of Canna (Scotland)

Related Fixed Station activities are detailed in Appendix 2

Fixed Station Information

DML Line HE

Line HE is a survey section in the Sea of the Hebrides, heading from Loch Bracadale (Isle of Skye, Scotland) in a south - south westerly direction towards the Isle of Canna. The line comprises five fixed CTD stations, which were established as part of routine monitoring work on the Scottish continental shelf by Dunstaffnage Marine Laboratory (DML). The line was occupied between the late 1970s to early 1990s.

Line HE has also occasionally been referred to as Line H.

Nominal station details

DML Line HE: Loch Bracadale - north west of Canna (Scotland)

Related Fixed Station activities are detailed in Appendix 3

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: DML Line HE Station HE1

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

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Appendix 2: DML Sea of the Hebrides STD/CTD Sections

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

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Appendix 3: DML Line HE

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

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.