Metadata Report for BODC Series Reference Number 1840973

• 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

CTD data from cruise JR17001 Quality Report

Screening and Quality Control

During BODC quality control, data were screened using in house visualisation software. The data were screened and any obvious outliers and spikes were looked at in closer detail and flagged if necessary.

Improbable flags ('M') were applied to the CPHLPR01 channel where values were negative. There were a number of outliers in the POPTDR01 channel but it was not deemed that these outliers were anomalous and therefore did not required flagging.

AHSFZZ01

This channel has been flagged where values are constant or increase with depth. The altimeter only collects good data within 100 m of the seabed and these instances of constant values or increases with depth occur more than 100 m from the seabed.

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 for JR17001 CTD

CTD Unit and Auxiliary Sensors

The CTD unit comprised a Sea-Bird Electronics (SBE) 9plus underwater unit, an SBE 11 plus deck unit, a 24-way SBE 32 carousel and 24 Niskin bottles; all of which were mounted on a stainless steel 24-way CTD frame. Attached to the CTD were two SBE 3P temperature sensors, two SBE 4C conductivity sensors, one SBE 43 dissolved oxygen sensor, one QCP2350 PAR sensor, one CTG Aquatracka MKIII fluorometer, one WetLabs C-Star transmissometer, one Tritech Altimeter, one SBE35 temperature sensor and a RDI LADCP.

* The secondary conductivity sensor was replaced during the cruise due to the output of the first sensor being spikey. The serial number of the first sensor was 2248 and the serial number of the second sensor was 2255.

** The LADCP was replaced during the cruise due to excessive file fragmentation. The LADCP was replaced by RDI Workhorse 300 kHz serial number 14897.

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.

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.

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.

BODC Data Processing of CTD casts from cruise JR17001

Data Processing

Files from 43 of the 44 CTD casts from cruise JR17001 were processed and submitted to BODC in .nc format. The cast that was not submitted was a test cast. The files were subsequently archived and transferred to BODC internal format using standard BODC procedures. The variables provided in the files were mapped to BODC parameter codes as follows:

The following parameters were derived by BODC when the data were transferred to internal BODC netcdf format:

The following originator's variables were not transferred to BODC internal format but are available on request:

• cond1, cond2 - the originator specfied cond as the preferred channel
• psal1, psal2 - the originator specfied psal as the preferred channel
• temp1, temp2 - the originator specfied temp as the preferred channel
• potemp, potemp1, potemp2 - the parameter is derived by BODC instead
• depth
• pressure_temp

Screening

Post transfer analysis and crosschecks were applied according to BODC procedures. This involved the screening of data using BODC's in house visualisation software where any suspect data were flagged but not removed. During screening, any data that were flagged as improbable by the originator were converted to BODC data flags.

Originator Data Processing of CTD casts from cruise JR17001

Sampling Strategy

A total of 44 CTD casts were performed during JR17001 with 34 of these casts were completed as part of the ORCHESTRA programme and the remaining 10 casts completed for the NERC-CONICYT ICEBERGS programme. 20 of the ORCHESTRA casts surveyed the SR1b line.

Data Processing

The CTD data were acquired using Seabird SeaSave version 7.22.3. Subsequently, the following three processes were run in SBE Data Processing:

• Data conversion - converted raw data from engineering units to binary .cnv files.
• AlignCTD - applied a time alignment offset to the oxygen data relative to pressure to compensate for hysteresis effects.
• CellTM - corrected conductivity data for cell thermal mass effects.

Any settings used during these steps were provided by the manufacturer.

Data were then processed using a suite of Matlab programs developed by the Ocean Circulation and Processing group at the National Oceanography Centre (NOC).

Calibrations

Temperature

The CTD temperature sensor was calibrated by comparison with SBE35 values obtained at the time of bottle firings. The calibration of the temperature sensors are as follows:

Conductivity

Conductivity calibrations were applied by comparing laboratory analysed values from Niskin water samples and CTD values at the time of bottle firing. The calibration of the sensors are as follows:

Oxygen

Dissolved oxygen calibrations were applied in post-cruise processing by comparing Winkler titration values from Niskin water samples and CTD values at the time of bottle firing.

Further information on the CTD processing can be found in section 12.2 of the cruise report.

Project Information

Impacts of deglaciation on benthic marine ecosystems in Antarctica

Impacts of deglaciation on benthic marine ecosystems in Antarctica (ICEBERGS) is one of three NERC-CONICYT joint funded projects running from 2017 to 2021. The aim of the programme is to investigate the impacts of physical disturbance arising from climate-warming induced deglaciation on benthic communities around the West Antarctic Peninsula.

Participants

There are four research institutions involved in the project:

• University of Bangor
• University of Exeter
• Universidad Católica de la Santísima Concepción
• British Antarctic Survey (BAS)

Research Details

In order to meet the aim of the project, the ICEBERGS consortium produced six objectives:

• Monitoring glacier retreat over time and scour intensity on the adjacent seabed.
• Determine the benthic assemblage structure from localities with different perturbation levels.
• Evaluate nutritional and reproductive conditions of adults.
• Analyse growth rates from bivalve/gastropod shells and bryozoan populations with different perturbation levels.
• Develop reconstructions of physical disturbance due to iceberg discharge from growth patterns present in the carbonate structure of the shells of marine molluscs.
• Estimate the effect of marine glacier discharge and iceberg scouring on the genetic diversity and connectivity of marine invertebrate populations and the role of dispersal potential.

Fieldwork and Data Collection

The fieldwork for the project consists of research cruises along the west Antarctic Peninsula across three field seasons on board the RRS James Clark Ross. Three sites (Marine Cove, William Glacier and Sheldon Glacier) were selected for the fieldwork using available bathymetry and glacier retreat data. The fieldwork covers physical oceanography, marine geology, habitat mapping, community structure and seabed sediments and consists of CTD deployments, multi-beam swath bathymetry surveys, TOPAS sub-bottom profiling, shallow underwater camera system deployments, plankton net deployments, Agassiz trawls, Hamon grabs and multi-corer deployments.

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: