Metadata Report for BODC Series Reference Number 898046

• 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

CTD unit and auxiliary sensors

The CTD system used on cruise JR127 was the BAS Sea-Bird 911 plus. The system consisted of twin pumped temperature and conductivity sensors, a pressure transducer and an SBE 32 twelve-position carousel water sampler, with each position having a 10 litre OTE bottle. The CTD was fitted with the following scientific sensors:

Calibration samples for salinity, oxygen and chlorophyll were taken during the cruise.

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.

BODC Processing

The data arrived at BODC in a total of 75 ASCII, WHP (WOCE Hydrographic Program) standard files, each representing the individual CTD casts deployed during the cruise. 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 samples at their original density were also supplied to BODC. These files contain some additional parameters compared to the 2db-din 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 format, a netCDF subset. 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.

RRS James Clark Ross Cruise 127 CTD Data Processing

Sampling Strategy

A total of 77 CTD casts were performed during the cruise which sailed from Stornoway to Ny Alesund in the Norwegian Sea before returning to Aberdeen. The first CTD deployed on the cruise was used as a test cast and one other suffered from a hydraulic fluid leak so a total of 75 CTD data files were produced during the cruise. The CTD system deployed during the cruise consisted of twin pumped temperature and conductivity sensors, a pressure transducer and an SBE 32 twelve-position carousel water sampler, with each position having a 10 litre OTE water sampling bottle. The CTD package was deployed from the midships gantry and hauled/veered on the CTD/hydro winch using the BAS conducting swivel. Bottles were fired during the ascent with descent and ascent speeds reaching a maximum of 1 m / second during long stretches below the upper 100 m of the water column.

Data Processing

Processing of the CTD data was performed using the Seasoft routines supplied by Sea-Bird. A batch file was written using the DOS based version 4.244 routines.

Raw data files were converted to engineering units and ASCII (.CNV) files using the DATCNV program. Sea-Bird bottle data files (.BTL), with information on pressure and other readings logged at the time of bottle firing, were also generated during the data conversion process using ROSSUM. 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 ahead of LOOPEDIT. The data was binned to 2 db intervals using the BINAVERAGE program and finally salinity, density and potential temperature were calculated using DERIVE prior to an output file being produced.

Field Calibrations

The final calibration of the CTD salinity sensor on the stainless steel frame took the form of an offset as given here;

• S_A = S_M + 0.00823

Where S_A is the actual salinity and S_M is the measured salinity

The final calibration of the CTD oxygen sensor on the stainless steel frame is given here;

• O_A = O_M / 0.9649 - 0.0987

With a correlation coefficient of R² = 0.6641

Where O_A is the actual salinity and O_M is the measured salinity

The temperature data were in excellent agreement with the reference SBE35 thermometer. Therefore, no further calibrations were applied.

References

Shimmield, G. et al, (2005). JR 127 Cruise Report, Scottish Association for Marine Science.

Project Information

Northern Seas Programme

The Northern Seas describes an area extending from the Irish and northern North Sea across the Norwegian Sea up to the marginal Arctic pack-ice zone, including territorial waters of the UK, Norway, Iceland, Denmark and Russia. These waters are an important marine environment playing a significant part in regulating world climate due to the area's role in thermocline circulation in addition to acting as a sink for man-made pollutants carried north by ocean currents. These environments are experiencing increasing pressures from both natural and human impacts and consequently the Northern Seas Programme was developed to help advance the understanding of how marine systems in Northern Seas respond to environmental and anthropogenic change.

Scientific Objectives

The central aim of the programme was to 'improve understanding of how the sensitivity of marine ecosystems to environmental perturbation, both natural and anthropogenic, varies along a latitudinal gradient'.

This aim was addressed through the following integrated themes:

Theme A: Understanding fjordic systems: insights for coastal and oceanic processes

Theme B: Ocean Margins: the interface between the coastal zone and oceanic realm

Theme C: Measuring and modelling change: sea sensors and bioinformatics

The Northern Seas Programme was active between 2001 and 2007. The fieldwork programme to address these objectives was conducted by staff from the Scottish Association for Marine Science (SAMS).

Northern Seas Programme Theme A

Theme A: Understanding fjordic systems: insights for coastal and oceanic processes

Due to the slow turnover of water within many fjords these systems can act as important models providing insights into major coastal and oceanic processes. This theme therefore addresses the aims of the Northern Seas Programme by focussing on the following sub-questions:

• Where and how is energy dissipated in fjords?
• How will pelagic microbial communities in northern coastal seas respond to changes in the quality and quantity of nutrient inputs?
• What are the important behavioural and physiological components of top-down control of sea loch ecosystems?
• How does bioturbation vary in response to environmental forcing and what are the consequences for redistribution of anthropogenic contaminants?
• Are deep-sea proxy-indicators of environmental and climatic change applicable to high-resolution sedimentary records in fjordic environments?

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: