Metadata Report for BODC Series Reference Number 934239

• 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

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 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.

Instrument Description - JC011 CTD

CTD unit and auxiliary sensors

The CTD system used on cruise JC011 was the Sea-Bird 911 plus (0720), with dual TC pairs. The CTD rosette carried 24 10 L Ocean Test Equipmet External Spring Water Samplers. The CTD was fitted with the following scientific sensors:

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.

Aquatracka fluorometer

The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.

The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.

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

Chelsea Technologies Group ALPHAtracka and ALPHAtracka II transmissometers

The Chelsea Technologies Group ALPHAtracka (the Mark I) and its successor, the ALPHAtracka II (the Mark II), are both accurate (< 0.3 % fullscale) transmissometers that measure the beam attenuation coefficient at 660 nm. Green (565 nm), yellow (590 nm) and blue (470 nm) wavelength variants are available on special order.

The instrument consists of a Transmitter/Reference Assembly and a Detector Assembly aligned and spaced apart by an open support frame. The housing and frame are both manufactured in titanium and are pressure rated to 6000 m depth.

The Transmitter/Reference housing is sealed by an end cap. Inside the housing an LED light source emits a collimated beam through a sealed window. The Detector housing is also sealed by an end cap. A signal photodiode is placed behind a sealed window to receive the collimated beam from the Transmitter.

The primary difference between the ALPHAtracka and ALPHAtracka II is that the Alphatracka II is implemented with surface-mount technology; this has enabled a much smaller diameter pressure housing to be used while retaining exactly the same optical train as in the Mark I. Data from the Mark II version are thus fully compatible with that already obtained with the Mark I. The performance of the Mark II is further enhanced by two electronic developments from Chelsea Technologies Group - firstly, all items are locked in a signal nulling loop of near infinite gain and, secondly, the signal output linearity is inherently defined by digital circuitry only.

Among other advantages noted above, these features ensure that the optical intensity of the Mark II, indicated by the output voltage, is accurately represented by a straight line interpolation between a reading near full-scale under known conditions and a zero reading when blanked off.

For optimum measurements in a wide range of environmental conditions, the Mark I and Mark II are available in 5 cm, 10 cm and 25 cm path length versions. Output is default factory set to 2.5 volts but can be adjusted to 5 volts on request.

Further details about the Mark II instrument are available from the Chelsea Technologies Group ALPHAtrackaII specification sheet.

WETLabs Single-angle Backscattering Meter ECO BB

An optical scattering sensor that measures scattering at 117°. This angle was determined as a minimum convergence point for variations in the volume scattering function induced by suspended materials and water. The measured signal is less determined by the type and size of the materials in the water and is more directly correlated to their concentration.

Several versions are available, with minor differences in their specifications:

• ECO BB(RT)provides analog or RS-232 serial output with 4000 count range
• ECO BB(RT)D adds the possibility of being deployed in depths up to 6000 m while keeping the capabilities of ECO BB(RT)
• ECO BB provides the capabilities of ECO BB(RT) with periodic sampling
• ECO BBB is similar to ECO BB but with internal batteries for autonomous operation
• ECO BBS is similar to ECO BB but with an integrated anti-fouling bio-wiper
• ECO BBSB has the capabilities of ECO BBS but with internal batteries for autonomous operation

Specifications

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

Tritech Digital Precision Altimeter PA200

This altimeter is a sonar ranging device that gives the height above the sea bed when mounted vertically. When mounted in any other attitude the sensor provides a subsea distance. It can be configured to operate on its own or under control from an external unit and can be supplied with simultaneous analogue and digital outputs, allowing them to interface to PC devices, data loggers, telemetry systems and multiplexers.

These instruments can be supplied with different housings, stainless steel, plastic and aluminum, which will limit the depth rating. There are three models available: the PA200-20S, PA200-10L and the PA500-6S, whose transducer options differ slightly.

Specifications

Common specifications are presented below

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

BODC processing JC011

There were 61 casts performed on the cruise with the first one being just a test and ten being yo-yo casts that were not part of this data submission. The remaining 50 casts were supplied to BODC in 50 separate PStar files with file one file for each cast. The data were then converted to NetCDF format by in-house generated Matlab code. The turbidity channel was found to not be recording sensible data. The instrument should be recording in voltages but all the values do not match the units and no sensible data was collected. The data were only usable for relative comparison but as it is mirrored by the transmissometer data it was decided to not transfer the turbidity data.

During the transfer the original parameters are mapped to unique BODC parameter codes. The mapping can be seen below.

Following transfer the data was screened using in-house visualisation software. Data points that were judged to be suspect were flagged with the appropriate BODC data qaulity control flag.

Originator's processing JC011

A total of 61 CTD casts were performed on cruise JC011 with the majority taking place around the Charlie-gibbs fracture zone of the Mid Atlantic Ridge. The first cast ,Cast 001, was a short cast in Bantry Bay to obtain sound velocity information to calibrate the EK60, and was not supplied to BODC. 10 of the casts were yo-yo casts and are not included in this data submission. The total number of casts supplied to BODC was 50. A full station log and more information on the CTD is available on page 70 of the cruise report which is accessible through the JC011 metadata summary.

The CTD data were calibrated with manufacturer's calibrations and processed though Sea-Bird software. Processing through Sea-Bird software usually comprises of running the data through set routines that smooth and average the data into a usable form. These steps produced calibrated, averaged 24 Hz data files.

The CTD data were then averaged to 1 second intervals by the originator before being averaged further to 2 db pressure PStar files. The salinity and oxygen channels were calibrated against discrete samples taken from the CTD niskin bottles. Higher resolution files are also available on request.

Project Information

ECOMAR Project

Introduction

ECOsystems of the Mid Atlantic Ridge at the sub-polar front and Charlie-Gibbs fracture zone (ECOMAR) is a £2 million NERC fundeed UK element of MAR-ECO: A field project of the Census of Marine Life. ECOMAR is split into six different work packages managed by seven differen UK research institutes. ECOMAR itself is aimed at understanding how physical and biogeochemical factors influence the distributions and structure of deep-sea communities, focusing on the fauna of the Mid-Atlantic Ridge.

Scientific objectives

The main scientific objectives of the project are as follows,

• To describe the physical flow regimes, both at the surface and the seafloor, across four sites located to either side of the sub-polar front, with reference to their specific role in mixing mutrients and influencing the down-ward transport of organic carbon
• By remote sensing, produce regional estimates of surface promary production and liekly export flux over the study area
• Measure the export flux of organic matter to the seafloor using sediment trap moorings located at each of the four study sites
• Compare the distribution and abundance of pelagic biomass in relation to the position of the Mid-Atlantic Ridge at either side of the Charlie-Gibbs Fracture Zone and to the accompanying varying regimes of primary production encountered either side of the Sub-Polar Front
• Measure benthic biodiversity and biomass comparing species composition with similar depths at East and West Atlantic margins using traps, suspended camera systems, landers and targeted ROV-based survey and sampling
• Assess the possible boundaries to gene flow at the MAR and Sub-Polar Front and also genetic population structure of target species in comparison with the East and West Atlantic margins. Representative vertebrate and invertebrate species with different life histories will be compared to test hypotheses about the relationship between MAR ecology, physical oceanographic factors and genetic dispersal.

• Field work

  The past and future cruises that form the fieldwork aspect of ECOMAR are described below

  Year	Cruise	Date	Further information
  2007	RRS James Cook JC011	13th July - 19th August	Cruise summary
  2008	RRS Discovery D331T	24th July - 15th August	Cruise summary
  2009	RRS James Cook JC037	1st August - 9th September	Cruise summary
  2010	RRS James Cook	Dates to be confirmed	-

  Contact information

  For further information on the project contact:

  ECOMAR Project Officer

  Dr. Nicola King Oceanlab,
  University of Aberdeen,
  Main Street,
  Newburgh,
  Aberdeenshire,
  Scotland,
  AB41 6AA

  Phone: +44 (0) 1224 274410

  E-mail: n.king@abdn.ac.uk

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: