Metadata Report for BODC Series Reference Number 938880

• 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.

JR210 CTD Instrument Description

CTD unit and auxiliary sensors

The CTD system used on cruise JR210 was the Sea-Bird 911 plus. This was mounted on a stainless steel rosette frame, equipped with 24 10-litre Niskin bottles. The CTD was fitted with the following scientific sensors:

The salinity samples from the CTD were analysed during the cruise in a constant temperature laboratory using the Guildline Autosal 8400 salinometer.

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 Log Quantum Cosine Irradiance Sensor QCD-905L

The QCD-905L is a submersible radiometer designed to measure irradiance over Photosynthetically Active Radiation (PAR) wavelengths (400-700 nm). It features a cosine directional response when fully immersed in water.

The sensor is a blue-enhanced high stability silicon photovoltaic detector with dielectric and absorbing glass filter assembly, and produces a logarithmic output. Normal output range is -1 to 6 volts with 1 volt per decade. Typically, the instrument outputs 5 volts for full sunlight and has a minimum output of 0.001% full sunlight, where typical noon solar irradiance is 1.5 to 2 x 10¹⁷ quanta cm^-2 s^-1. The instrument can be calibrated with constants for µE cm^-2 s^-1 or quanta cm^-2 s^-1.

The QCD-905L can be coupled to a fixed range data acquisition system like a CTD (Conductivity-Temperature-Depth) profiler or current meter. It has an aluminium and PET housing, and a depth rating of 7000 m.

Specifications

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

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.

JR210 CTD BODC Processing

Data arrived at BODC in a total of 50 ASCII, WHP (WOCE Hydrographic Program) standard files representing the CTD casts deployed during cruise JR210. These files contain 2db-bin averaged data including temperature, salinity and dissolved oxygen channels processed to WOCE standards alongside concurrent fluorometer and transmissometer data.

Additional 24 Hz ASCII files containing data sampled at their original density were also supplied to BODC. These files contain some additional parameters compared to the 2db-bin averaged data files but due to having fewer quality control procedures applied these data have not undergone any further BODC processing. They have however been archived at BODC in their original format and are available upon request.

The lodged WHPO standard casts were reformatted to BODC's internal QXF format. The following table shows the mapping of variables within the ASCII files to appropriate BODC parameter codes:

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, and missing data marked by both setting the data to an appropriate value and setting the quality control flag.

JR210 CTD Originator's Processing

Sampling Strategy

A total of 50 CTD casts were performed during the cruise which sailed from Portland in Dorset along the English Channel and into the North Sea passing the Norweigan coast, up into the Arctic Circle and onto the island group of Svalbard. The CTD was equipped with dual temperature and conductivity sensors, an SBE43 dissolved oxygen sensor, fluorometer, transmissometer and PAR sensor in addition to an independent SBE35 thermometer, all located within and near the bottom of the rosette frame which held 24 10-litre Niskin water sampling bottles. The CTD was usually deployed on the winch on the starboard side of the ship except on a few occassions when the stern gantry was used as icy conditions did not allow for working on the side of the ship. Bottles were fired during the ascent with descent and ascent speeds reaching a maximum of 1 ms^-1 during long stretches below the upper 100 m of the water column.

Data Processing

Following the completion of each CTD cast the data were saved to the deck unit PC and transferred over the network to a Unix data disk. SBE Seasave Win32 V 7.15 software was used to perform all processing steps.

Raw data files were converted to engineering units and binary .CNV files using the DATCNV program. The WILDEDIT program was run to remove any large pressure spikes and then the SeaSoft program ALIGNCTD was run to advance the oxygen measurements by 4 seconds ensuring the calculations of dissolved oxygen concentration are made using measurements from the same parcel of water. CELLTM was run, according to Sea-Bird's recommendations, to remove conductivity cell thermal mass effects from the measured conductivity and FILTER was run on the pressure channel using a low-pass filter value of 0.2 to smooth the rapidly changing data. Twin salinities, density and depth were calculated using the DERIVE program and TRANSLATE wrote the data to an ASCII output .CNV file. Finally, the module BOTTLESUM created the ASCII bottle files (.BTL) for each bottle fired during a cast, with information on pressure and other readings logged at the time of bottle firing.

Despiking of the pressure, oxygen, temperature and salinity data was carried out manually by visualising the data in MATLAB. If a spike occured in pressure, temperature or salinity the whole corresponding scan has been deleted. If the spike occurs in the other channels, the value was set to NaN and all remaining channels were left unedited. Following despiking of the data in MATLAB the module BINAVERAGE averaged the 24 Hz data into 2db-bins, using the downcast data only.

Calibrations

For the CTD casts the following calibrations were applied;

• Sal1_calibrated = 0.9691 Sal1_uncalibrated + 1.08
• Sal2_calibrated = 0.9674 Sal2_uncalibrated + 1.1448

• Ox_calibrated = 0.7373 Ox_uncalibrated + 0.5593 (units: mgl^-1)

References

Leakey, R. J. G. 2008. ICE CHASE (Changing Sea-ice and Ecosystem Response) RRS JAMES Clark Ross (JR210), Oceans 2025 Arctic Cruise Report.

Project Information

Oceans 2025 Theme 1, Work Package 1.6: The Effect of Climate Change on the Arctic marine system

This Work Package is run by the Scottish Association for Marine Science (SAMS). Observational and experimental studies will be undertaken in ice-covered and open waters of the western Barents Sea and the northern Svalbard region for which understanding of the physical oceanography is relatively well advanced, and where seasonal access via a UK ice-strength research vessel (RRS James Clark Ross) and installation of year-round in situ instrumentation are feasible.

These studies will complement previous observational and experimental studies undertaken in the western/central Barents Sea (Wassmann, 2002) and will be used, along with published data sets and remotely-sensed data, to parameterise and test a coupled physical-biological model, which will be developed in collaboration with the Proudman Oceanographic Laboratory (POL), in the UK. This model will allow comparison with similar modelling studies undertaken in Arctic waters, including the western/central Barents Sea (Wassman et al., 2006); it will also advance the current state of the art by improved parameterisation of microbial rate processes, and by the incorporation of benthic and sea-ice biogeochemical processes and feedbacks.

This approach, encompassing ship, instrument and modelling platforms, will provide the UK with an enhanced strategic capability to undertake, and be informed by, research on the consequences of rapid climate change in the Arctic.

More detailed information on this Work Package is available at pages 17 - 19 of the official Oceans 2025 Theme 1 document: Oceans 2025 Theme 1

Weblink: http://www.oceans2025.org/

References:

Wassmann P., 2002. Seasonal C-cycling variability in the open ocean and ice-covered waters of the Barents Sea: an introduction, J Mar Syst, 38, 1-7

Wassmann P., Slagstad D., Wexels Riser C., and Reigstad M., 2006. Modelling the ecosystem dynamics of the Barents Sea including the marginal ice zone, II Carbon flux and interannual variability, J Mar Syst, 59, 1-24

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: