Metadata Report for BODC Series Reference Number 1167210

• 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

Public domain 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.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Seapoint Chlorophyll Fluorometer

The Seapoint Chlorophyll Fluorometer (SCF) is a low power instrument for in situ measurements of chlorophyll a. The SCF uses modulated blue LED lamps and a blue excitation filter to excite chlorophyll a. The fluorescent light emitted by the chlorophyll a passes through a red emission filter and is detected by a silicon photodiode. The low level signal is then processed using synchronous demodulation circuitry which generates an output voltage proportional to chlorophyll a concentration. The SCF may be operated with or without a pump.

Sensor specifications, current at August 2006, are given in the table below. More information can be found at the manufacturer's web site.

Sensor Specifications

Aanderaa Conductivity Sensors 3919/4119/4120

The Aanderaa Conductivity Sensors are based on an inductive principle. This provides for stable measurement without electrodes that are easily fouled and may wear out in the field.

All sensors are available in A and B versions; version B has enhanced accuracy compared to version A. Additionally, sensor 3919 is available in three depth ratings as well: 6000 m (3919DW; Deep Water), 2000 m (3919IW; Intermediate Water) and 300 m (3919SW; Shallow Water).

The sensors are compact fully integrated sensors for measuring the electrical conductivity of seawater. The 3919 model is designed to be mounted directly on the top-end plate of Recording Conductivity Sensor (RCM) 9/11 and Recording Doppler Current Profiler (RDCP) as well as for standalone operation via the SR10 or RS-232 interface. The 4119 model can be connected via cable to a AADI SR10/VR22 Data logger, and the 4120 model provides analog output to third party loggers.

Features of the conductivity sensors:

• Smart sensor technology - provides calibrated data directly
• Real-time integrated calculation of salinity, density and sound of speed
• Low maintenance needs
• Easy functionality check
• 3 depth ranges, maximum 6000 m.
• Internal pressure never exceeds 1 bar therefore electronics and sensors are unaffected by sea depth
• Output format: SR10, RS-232, Analog 0-5 V/ 4-20 mA

Sensor specifications may be viewed via the following link Aanderaa Conductivity Sensor 3919/4119/4120

Aanderaa Oxygen Optodes models 3835, 4130, 4175, 3830, 3930 and 3975

The Aanderaa Oxygen Optode is based on the ability of selected substances to act as dynamic fluorescence quenchers. The fluorescent indicator is a special platinum porphyrin complex embedded in a gas permeable foil that is exposed to the surrounding water.

A black optical isolation coating protects the complex from sunlight and fluorescent particles in the water. This sensing foil is attached to a window providing optical access for the measuring system from inside a watertight titanium housing.

The foil is excited by modulated blue light, and the phase of a returned red light is measured. By linearizing and temperature compensating, with an incorporated temperature sensor, the absolute O₂ concentration can be determined. According to the manufacturer, the lifetime-based luminescence quenching principle offers the following advantages over electro-chemical sensors:

• Not stirring sensitive (it consumes no oxygen)
• Less affected by fouling
• Measures absolute oxygen concentrations without repeated calibrations
• Better long-term stability
• Less affected by pressure
• Pressure behaviour is predictable
• Faster response time

The 3835, 4130 and 4175 models are designed to operate down to 300 m, while there are two versions of the 3830, 3930 and 3975 models, designed to operate down to 2000 m and 6000 m, respectively. The sensors fit directly on to the top end-plate of Recording Current Meter RCM 9, and other Aanderaa instruments. Sensor specifications may be viewed via the following links: Aanderaa Oxygen Optodes 3835/4130/4175 and Aanderaa Oxygen Optodes 3830/3930/3975.

Seapoint Turbidity Meter

The Seapoint Turbidity Meter detects light scattered by particles suspended in water, generating an output voltage proportional to turbidity or suspended solids. Range is selected by two digital lines which can be hard wired or microprocessor controlled, thereby choosing the appropriate range and resolution for measurement of extremely clean to very turbid waters. The offset voltage is within 1 mV of zero and requires no adjustment across gains. The optical design confines the sensing volume to within 5 cm of the sensor allowing near-bottom measurements and minimizing errant reflections in restricted spaces.

Sensor specifications, current at August 2006, are given in the table below.

Sensor Specifications

** output is non-linear above 750 FTU.

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

Data processing by originator

Instruments and methods for all North Dogger SmartBuoy deployments are described by Greenwood et al. (2010). The thermocline-depth rig on the SmartBuoy mooring was equipped with the following instruments:

In situ measurements

In situ sensors were mounted at 31 m depth on the mooring. A solid state data logger (ESM-2) designed and built by Centre for Environment, Fisheries and Aquaculture Science (Cefas, UK) was used for data acquisition and sensor control. Measurements were recorded at a frequency of 1 Hz for turbidity, chlorophyll fluorescence and temperature and conductivity from FSI sensors and at 5 Hz for Aanderaa optode and Aanderaa conductivity sensors, with a burst frequency of 2 per hour and a burst duration of between 5 and 10 min depending on the length of mooring deployment.

The in situ chorophyll, salinity, oxygen and suspended particulates data were bench calibrated.

Discrete sample collection and analysis

Discrete samples for calibration were collected by CTD rosette sampler, during visits to the mooring. Data from CTD samples have not been merged into the mooring data set.

References

Greenwood N., Parker E.R., Fernand L., Sivyer D.B., Weston K., Painting S.J., Kröger S., Forster R.M., Lees H.E., Mills D.K., Laane R.W.P.M., 2010. Detection of low bottom water oxygen concentrations in the North Sea; implications for monitoring and assessment of ecosystem health. Biogeosciences, 7, 1357-1373.

Processing by BODC

The processed and quality-controlled data were supplied to BODC in a bulk, ASCII format file. Accompanying files provided instrument metadata. The data were converted into BODC's standard format, with one file for each rig deployment. The data were visually screened, taking into account comparisons between related parameters, and the environmental context. No major data issues were identified, but there may be some gaps in the data series, due to instrument failures.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

North Dogger SmartBuoy, January to April 2008

This SmartBuoy mooring was deployed by CEFAS north of Dogger Bank, 55° 40.27'N, 2° 17.88'E.

Two sensor suites were deployed on the mooring, one near-surface and one at thermocline depth.

Instruments deployed on the mooring

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Cefas North Dogger SmartBuoy mooring site

Cefas maintained a SmartBuoy mooring site at the north of Dogger Bank, 55°40.27'N, 2°17.88'E, in approximately 80 m of water, from 24/02/2007 to 15/09/2008.

Normally two sensor suites were deployed on the mooring during each deployment: one near-surface (about 1 m); and one at thermocline depth (25 m or 31 m).

The near-surface frame was typically equipped as follows:

The mid-tether frame was typically equipped as follows:

The SmartBuoy mooring was first deployed on Cefas Endeavour cruise 3/07. Data were relayed to shore every two hours. The mooring was deployed for several months at a time, after which it was serviced, sensors replaced or repositioned, samples recovered, and then it would be re-deployed. In total, there were seven individual deployments at the North Dogger site:

SmartBuoy deployments at the North Dogger site were funded by Marine Ecosystem Connections: essential indicators of healthy, productive and biologically diverse seas, a project funded by the UK Government's Department for Environment, Food and Rural Affairs (Defra project code ME3205).

Related Fixed Station activities are detailed in Appendix 2

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:

Appendix 1: NDOGGER_JAN08_APR08

Related series for this Data Activity are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Appendix 2: Cefas North Dogger

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.