Metadata Report for BODC Series Reference Number 574422

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The SBE 13 instrument has been out of production since 2001 and has been superseded by the SBE 43.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

SeaTech Transmissometer

Introduction

The transmissometer is designed to accurately measure the the amount of light transmitted by a modulated Light Emitting Diode (LED) through a fixed-length in-situ water column to a synchronous detector.

Specifications

• Water path length: 5 cm (for use in turbid waters) to 1 m (for use in clear ocean waters).
• Beam diameter: 15 mm
• Transmitted beam collimation: <3 milliradians
• Receiver acceptance angle (in water): <18 milliradians
• Light source wavelength: usually (but not exclusively) 660 nm (red light)

Notes

The instrument can be interfaced to Aanderaa RCM7 current meters. This is achieved by fitting the transmissometer in a slot cut into a customized RCM4-type vane.

A red LED (660 nm) is used for general applications looking at water column sediment load. However, green or blue LEDs can be fitted for specilised optics applications. The light source used is identified by the BODC parameter code.

Further details can be found in the manufacturer's Manual.

RV Scotia 15/2001 CTD Data Documentation

Instrumentation

The instrument used was a Sea-Bird SBE911plus.

Details of the sensors on the CTD are -

Calibrations

Fluorometer

Internal 1000ug/l
CON file scale factor 3
offset 0

Internal set wrongly should have been set to 3ug/l.

The following fluorometer calibration was obtained from FRS after the data had been added to the BODC data bank. It has not been applied to the data held by BODC.

Fluor(ug/l) = 0.0628*Fluor(volts) + 0.212

R² = 0.6924
Calibration points used = 14 out of a total of 54

The fluorometer was set incorrectly for part of the cruise and consequently there were no readings for 30 of the calibration samples. The quality of this data is not good.

Transmissometer

Set to 1,0

Temperature and Conductivity

The following temperature and conductivity calibrations have been applied:

T(cal) = T(obs)
C(cal) = 0.999820C(obs) + 0.006623

Information

For further information, contact:

George Slesser
Ocean Climate Group
FRS, Marine Laboratory Aberdeen
PO Box 101
Victoria Road
Aberdeen AB11 9DB
G.Slesser@marlab.ac.uk

Project Information

Monitoring the Atlantic Inflow toward the Arctic (MAIA)

Introduction

MAIA is an EU Fifth Framework Programme supporting Key Action 2 (Global Change, Climate and Biodiversity) of Theme 4: Energy, Environment and Sustainable Development. The overall objective of MAIA is to develop an inexpensive and reliable system based on coastal sea level data for monitoring the inflows of Atlantic water into the northern seas.

Scientific Rationale

The flux of Atlantic Water to the northern seas is vital for the existence of life in northern Europe. More than half of the Atlantic Water appears to enter the Norwegian Sea to the west of the Faroe Islands. A lesser, warmer amount enters along the continental margin past Scotland. There have been several attempts to estimate and monitor these fluxes and see how the ice extent in the north is correlated to them.

The special goals of MAIA are:

• to monitor the inflow of salt and heat to the northern seas for the analysis of climate variability, distinguishing between warmer (eastern) and cooler (western) inflow past the Faroes, and the major routes through the Barents Sea, with a time resolution better than a week, a spatial resolution of the major routes and an accuracy better than 15%.

• to understand the causes of errors and recommend strategies to improve the future accuracy of such a monitoring tool.

Project Components

The project was divided into 3 phases:

• Phase I

  Phase I was to analyse historical observations of sea-level fluctuations during the past decade and compare them with available bottom pressure and in situ current velocity measurements in the region of interest.

• Phase II

  Phase II is a dedicated validation study in the Shetland- Iceland region and in the Barents Sea to verify that the system can give the required results to the desired accuracy and resolution. The validation period was from summer 2000 to November 2001.

• Phase III

  Phase III of the project includes evaluating the validations, the effects of external influences and the ice studies, and making recommendations for future monitoring.

Data Activity or Cruise Information

Cruise

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:

SeaDataNet Quality Control Flags

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