Metadata Report for BODC Series Reference Number 2246843

• 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

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.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

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.

JR18004 CTD (Conductivity-Temperature-Depth) Instrumentation

The Sea-Bird Scientific SBE9plus CTD was mounted on a rosette with an SBE32 carousel water sampler and 24 Niskin bottles (20 L and 12 L). The SBE9plus was connected through the sea cable to an SBE11plus deck unit. The CTD package was deployed from the mid-ships gantry on a cable connected to the CTD through a conducting swivel. 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.

Sea-Bird SBE 9plus CTD

High precision and accuracy CTD comprising an SBE 9plus underwater unit (SBE 3plus temperature, SBE 4C conductivity, and Paroscientific Digiquartz pressure sensors, and an SBE 5T submersible pump). Can be used for either real-time data acquisition or for autonomous operations at a sampling speed of up to 24 Hz. The instrument package also includes a TC duct, to reduce salinity spiking caused by ship heave for improved resolution of water column features, and to ensure that temperature and conductivity measurements are made on the same parcel of water. Supplied with both an aluminium and titanium main housing, allowing for use up to 6800 and 10,500 metre depths respectively. Also capable of measuring from eight auxiliary sensors.

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/SeaBird_SBE_9plus_Manual.pdf

SeaBird SBE35 Deep Ocean Standards Thermometer

The SBE 35 is a high precision thermometer that can be used in fixed point cells or at depths up to 6800 m. It is not affected by shock and vibration, allowing it to be used in calibration laboratories and for thermodynamic measurement of hydro turbine efficiency.

The SBE35 can be used with the SBE32 Carousel Water Sampler and with a real-time or autonomous CTD system. In this case, an SBE35 temperature measurement is collected each time a bottle is fired and the value is stored in EEPROM (Electrically Erasable Programmable Read-Only Memory), eliminating the need for reversing thermometers while providing a high accuracy temperature reading.

The SBE35 is standardized in water triple point (0.0100 °C) and gallium melting point (29.7646 °C) cells, following the methodology applied to the Standard-Grade Platinum Resistance Thermometer (SPRT). However, it does not need a resistance bridge, making it more cost-efficient than an SPRT.

Temperature is determined by applying an AC excitation to reference resistances and an ultrastable aged thermistor. Each of the resulting outputs is digitized by a 20-bit A/D converter. The AC excitation and ratiometric comparison uses a common processing channel, which removes measurement errors due to parasitic thermocouples, offset voltages, leakage currents and gain errors.

Specifications

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

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.

Biospherical Instruments QCP-2350 [underwater] PAR sensor

A cosine-corrected PAR quantum irradiance profiling sensor. For use in underwater applications with 24 bit ADC systems. Measures light available for photosynthesis on a flat surface. Operation is by a single channel compressed analog output voltage that is proportional to the log of incident PAR (400-700 nm) irradiance. The sensor is designed for operation in waters to depths of up to 2,000 m (standard) or 6,800 m (optional).

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/Biospherical_QCP2300_QCP2350_Apr2014.pdf

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.

Sea-Bird SBE 5 submersible pump series

The SBE 5 pump series includes the 5T (titanium) and 5P (plastic) models. It is a modular component on several Sea-Bird CTD packages, and is standard equipment on the SBE 9plus CTD and 25/25plus Sealogger CTD. The pump flushes water through the conductivity cell at a constant rate independent of the CTD's motion, improving dynamic performance. Models in the series differ in housing material and depth rating: the 5T model has a titanium housing, allowing it to reach depths of up to 10,500 metres, while the 5P model uses a plastic housing with a depth limit of 600 metres. The pump may also be suitable for custom applications, where pressure heads are in less than 300 cm of water and flow rates are less than 100 mL/sec. The 5 series features a centrifugal pump head, ball-bearing motor, and several motor speed options (1300, 2000, 3000, and 4500 rpm speeds) to meet various flow requirements.

For more information, please see this document: https://www.bodc.ac.uk/data/documents/nodb/pdf/SBE_5_pump.pdf

WETLabs C-Star transmissometer

This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.

Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.

This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.

Specifications

Further details are available in the manufacturer's specification sheet or user guide.

Processing by BODC of JR18004 CTD (Conductivity-Temperature-Depth) Data

The JR18004 RRS James Clark Ross cruise departed Punta Arenas, Chile on 6th January 2019, and returned to Punta Arenas, Chile on 17th February 2019. In total 61 CTD (Conductivity-Temperature-Depth) cast deployments were used to obtain profiles of the water column from a range of sensors compromising of temperature, conductivity, dissolved oxygen, transmissometer, fluorometer and PAR sensors. The Sea-Bird Scientific SBE9plus CTD was mounted on a rosette with a SBE32 carousel water sampler and 24 Niskin bottles (20 L and 12 L), and was connected through the sea cable to a SBE11plus deck unit in the Underway Instrumentation Control room (UIC). The CTD data were supplied to BODC as 61 MATLAB files.

Basic checks of the data and metadata were carried out and the data were subsequently transferred to BODC internal format (a netCDF subset). During transfer the originator's variables were mapped to unique BODC parameter codes, and some variables were derived by BODC from originator variables. The following table shows the parameter mapping:

Following transfer the data were screened using BODC in-house visualisation software. Any suspect data were flagged using the BODC quality control flags.

Processing by originator of JR18004 CTD (Conductivity-Temperature-Depth) Data

Sampling Strategy

The JR18004 RRS James Clark Ross cruise departed Punta Arenas, Chile on 6th January 2019, and returned to Punta Arenas, Chile on 17th February 2019. In total 61 CTD (Conductivity-Temperature-Depth) cast deployments were used to obtain profiles of the water column from a range of sensors compromising of temperature, conductivity, dissolved oxygen, transmissometer, fluorometer and PAR sensors. The Sea-Bird Scientific SBE9plus CTD was mounted on a rosette with a SBE32 carousel water sampler and 24 Niskin bottles (20 L and 12 L), and was connected through the sea cable to a SBE11plus deck unit in the Underway Instrumentation Control room (UIC).

The altimeter returns teal-time accurate measurements of the height off the seabed within approximately 100 m of the bottom. CTD data were collected at 24 Hz and logged via the deck unit into a PC running Seasave version 7.22.3 (Sea-Bird Scientific), which allows real-time viewing of the data.

The procedure was to start data logging during deployment of the CTD, then stop the winch at 10m wire out, where the CTD package was left for at least 2 minutes to allow the conductivity-activated pumps to switch on and the sensors to equilibrate with ambient conditions. The pumps consistently switched on 60 seconds after the instrument entered the water.

After the 10 m soak, the CTD was raised to as close to the surface as sea conditions allowed and then lowered to within 10 m of the seabed. The CTD was left at this depth for ~10 seconds to allow the SBE35 temperature sensor to take readings over 8 data cycles.

Data Acquisition and Initial Processing

The SBE Data Processing module Datcnv was used to convert the hex files to ascii format. These files were aligned to account for the time lag of the oxygen sensor, with data being advanced by 5 seconds. The cell thermal mass (celltm) module was then used to remove the conductivity cell thermal mass effects from the measured conductivity. This rederives pressure and conductivity, taking into account the temperature of the pressure sensor and the action of pressure on the conductivity cell. These were output in an ascii file (.cnv format).

During CTD calibration calculation differences were discovered between the primary and secondary conductivity sensors. Comparing to salinity samples this appears to be due to the secondary conductivity sensor. The offset between the two sensors changed during the course of the cruise, and it is noticeably greater at station 10.

Please see the JR18004 cruise report for details of the calibration coefficients applied to the data for all casts, including salinity calibration.

During processing, the CTD data from all casts were averaged (down-casts and up-casts combined, median value) into 2 db, and supplied to BODC. The data were output into MATLAB files.

Project Information

Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA)

The Ocean Regulation of Climate by Heat and Carbon Sequestration and Transports (ORCHESTRA) is a £8.4 million, five year (2016-2021) research programme funded by the Natural Environment Research Council (NERC). The aim of the research is to to advance the understanding of, and capability to predict, the Southern Ocean's impact on climate change via its uptake and storage of heat and carbon. The programme will significantly reduce uncertainties concerning how this uptake and storage by the ocean influences global climate, by conducting a series of unique fieldwork campaigns and innovative model developments.

Background

ORCHESTRA represents the first fully-unified activity by NERC institutes to address these challenges, and will draw in national and international partners to provide community coherence, and to build a legacy in knowledge and capability that will transcend the timescale of the programme itself.

It brings together science teams from six UK research institutions to investigate the role that the Southern Ocean plays in our changing climate and atmospheric carbon draw-down. It is led by British Antarctic Survey, in partnership with National Oceanography Centre, British Geological Survey, Plymouth Marine Laboratory, the Centre for Polar Observation and Modelling and the Sea Mammal Research Unit.

The oceans around Antarctica play a critical a key role in drawing down and storing large amounts of carbon and vast quantities of heat from from the atmosphere. Due to its remoteness and harsh environment, the Southern Ocean is the world's biggest data desert, and one of the hardest places to get right in climate models. The ORCHESTRA programme will make unique and important new measurements in the Southern Ocean using a range of techniques, including use of the world-class UK research vessel fleet, and deployments of innovative underwater robots. The new understanding obtained will guide key improvements to the current generation of computer models, and will enhance greatly our ability to predict climate into the future.

The scope of the programme includes interaction of the Southern Ocean with the atmosphere, exchange between the upper ocean mixed layer and the interior and exchange between the Southern Ocean and the global ocean.

Further details are available on the ORCHESTRA page.

Participants

Six different organisations are directly involved in research for ORCHESTRA. These institutions are:

• British Antarctic Survey (BAS)
• National Oceanography Centre (NOC)
• Plymouth Marine Laboratory (PML)
• British Geological Survey (BGS)
• Centre for Polar Observation and Modelling (CPOM)
• Sea Mammal Research Unit (SMRU)

GO-SHIP are a third party organisation that, although not directly involved with the programme, will conduct ship based observations that will also be used by ORCHESTRA.

Research details

Three Work Packages have been funded by the ORCHESTRA programme. These are described in brief below:

• Work Package 1: Interaction of the Southern ocean with the atmosphere
  WP1 will use new observations of surface fluxes and their controlling parameters in order to better constrain the exchanges of heat and carbon loss across the surface of the Southern Ocean.

• Work Package 2: Exchange between the upper ocean mixed layer and the interior.
  This work package will combine observationally-derived data and model simulations to determine and understand the exchanges between the ocean mixed layer and its interior.

• Work Package 3: Exchange between the Southern Ocean and the global ocean .
  This WP will use budget analyses of the hydrographic/tracer sections to diagnose the three-dimensional velocity field of the waters entering, leaving and recirculating within the Southern Atlantic sector of the Southern ocean.

• Fieldwork and data collection

  The campaign consists of 12 core cruises on board the NERC research vessels RRS James Clark Ross and RRS James Cook and will include hydrographic/tracer sections conducted across Drake Passage (SR1b), the northern Weddell Sea/Scotia Sea (A23), the northern rim of the Weddell Gyre (ANDREXII) and across the South Atlantic (24S). Section I6S will be performed by GO-SHIP Project Partners. Measurements will include temperature, salinity, dissolved oxygen, velocity, dissolved inorganic carbon, total alkalinity, inorganic nutrients, oxygen and carbon isotopes, and underway meteorological and surface ocean observations including pCO₂.

  Tags will be deployed on 30 Weddel seals and these will provide temperature and salinity profiles that can be used alongside the Argo data.

  Autonomous underwater ocean gliders will conduct multi-month missions and will deliver data on ocean stratification, heat content, mixed layer depth and turbulent mixing over the upper 1 km, with previously-unobtainable temporal resolution. These gliders will be deployed in the Weddell Gyre and the ACC.

  Field campaigns with the MASIN meteorological aircrafts will be conducted flying out of Rothera and Halley research stations and the Falkland Islands. These campaigns will deliver information on key variables relating to air-sea fluxes (surface and air temperature, wind, humidity, atmospheric CO₂, radiation, turbulent fluxes of heat, momentum and CO₂), in different sea ice conditions and oceanic regimes.

  Eart Observation datasets will be used to inform the programme on the properties of the ocean, sea ice and atmosphere and on interactions between them.

  A cluster of 6 deep ocean moorings in the Orkney Passage will collect year round series of AABW temperatre and transport. This work connects to the NERC funded project Dynamics of the Orkney Passage Outflow (DYNOPO).

  The UK Earth System model (UKESM) and underlying physical model will be used to conduct analyses of heat and carbon uptake and transport by the Southern Ocean and their links to wider climate on decadal timescales.

  An eddy-resolving (1/12°) sector model of the ocean south of 30°S with 75 vertical levels, will be built using the NEMO model coupled to the Los Alamos sea ice (CICE) model. The improvements on the ocean boundary layer will be based from the results from the NERC-funded OSMOSIS project and the inclusion of tides.

  20-5 year runs of an adjoint model will be conducted to determine how key forcings and model states affect the uptake and subduction of heat and carbon by the ocean.

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: