Metadata Report for BODC Series Reference Number 747740
Cast CO13/04/16: Cefas report a malfunctioning fast thermistor sensor which has resulted in incorrect data in many parameters during this cast. The affected parameters are Temperature, Salinity, Potential temperature, Sound velocity, Sig-th, Sigma-t and Light attenuation. The range of paramters affected would suggest a bigger problem than just a thermistor malfunction but no further explanation has been provided. No replacemnet file is expected
Cast CO13/04/16: No PAR data were collected for this cast. No reason is given for this omission.
Centre for Environment, Fisheries and Aquaculture Science (Cefas) data access conditions
The Centre for Environment, Fisheries and Aquaculture Science (Cefas) is an Executive Agency of the Department of Environment, Food and Rural Affairs (Defra), formerly the Ministry of Agriculture, Fisheries and Food (MAFF). It was also known previously as the Directorate of Fisheries Research (DFR). This data policy refers to data collected by the organisation under all titles.
- These data have no specific confidentiality restrictions for academic users. However data are restricted for commercial requests and clearance must be obtained by BODC from Cefas before they are released.
- 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 acknowledgement.
- The recommended acknowledgement is: "This study uses data from the Centre for Environment, Fisheries and Aquaculture Science (Cefas), provided by the British Oceanographic Data Centre."
Falmouth Scientific NXIC CTD Series
The FSI NXIC CTD Series is a collection of rugged Conductivity-Temperature-Depth profilers that utilise the patented Non-eXternal Inductive Cell (NXIC) conductivity sensor, which was originally developed for the US Navy DT-705 Sound Velocity/Salinity sensor. The CTDs are fast sampling, fully integrated instruments with optional battery power, datalogging and external analog sensor input.
Models in the collection include the NXIC CT Bio Direct Read-500M, NXIC CTD Bio Direct Read-500M, NXIC CTD Bio Auto-500M, NXIC CTD Direct Read-500M, NXIC CTD Direct Read-700M, NXIC CTD Auto-500M, NXIC CTD Auto-700M, NXIC CTD-ADC with external sensors, and the NXIC ETSG Thermosalinograph. Parameters are measured to an accuracy ranging from 0.002-0.010 mS/cm for conductivity, 0.005 degC for temperature and 0.08% for full scale pressure. Now marketed by Teledyne RD Instruments.
|Sensor type||Inductive cell||Thermistor||Precision-machined Silicon|
|Range||0 to 9.0 S m-1||-5 to 45°C||user specified|
|Accuracy||± 0.0002 S m-1||± 0.005°C||0.08 % full scale|
|Stability||± 0.00005 S cm-1 month-1||0.0005°C month-1||± 0.004 %|
|Resolution||0.00001 S m-1||0.001°C||0.001 % full scale|
|Response||5.0 cm at 1 m sec-1 flow||100 msec||25 msec|
CTD Unit and Auxillary Sensors
The CTD used was a Falmouth Scientific Inc (FSI) with serial number 1351. Seawater samples were collected for analysis to allow calibration for the instruments conductivity sensor. Digital reverse thermometers were used to compare with the CTD temperature sensor. A Chelsea fluorometer was used at all stations and was calibrated by chlorophyll samples. A Seapoint turbidity sensor was used and calibrated by suspended particulate matter analysis. A Licor photosynthetically-active-radiation sensor was fitted to the CTD and calibrated according to LiCor Amplifier and Sensor calibrations.
A list of calibrated parameters and instrumentation used is shown below.
|Pres||Pressure||dbar||FSI CTD s/n 1351|
|Temp||Temperature||deg C||Temperature sensor fitted to CTD|
|Salinity||Salinity||N/A||CTD s/n 1351|
|Pot||Potential Temperature||deg C||-|
|Turb||Turbidity||Volts||Seapoint turbidity sensor|
|Sl||Suspended Load||mg/l||Seapoint turbidity sensor|
|PAR||Photosynthetically Active Radiation||(ue/m^2/s)||LiCor light sensor|
|Chl||Chlorophyll||(mg/m^3)||Seapoint fluorometer s/n 2359|
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.
|Power requirements||8 - 20 VDC, 15 mA avg., 27 mA pk.|
|Output||0 - 5.0 VDC|
|Output Time Constant||0.1 sec.|
|Power-up transient period||< 1 sec.|
|Excitation Wavelength||470 nm CWL, 30 nm FWHM|
|Emission Wavelength||685 nm CWL, 30 nm FWHM|
|Sensing Volume||340 mm3|
|Minimum Detectable Level||0.02 µg l-1|
|Gain||Sensitivity, V µg-1 l-1||Range, µg l-1|
LI-COR LI-192 Underwater Quantum Sensor
The LI-192 Underwater Quantum Sensor is used to measure photosynthetic photon flux density and is cosine corrected. The sensor is often referred to as LI-192SA or LI-192SB (the LI-192SB model was superseded by LI-192SA). One of the main differences is that the LI-192SA model includes a built-in voltage output for interfacing with NexSens iSIC and SDL data loggers.
(Specifications apply to both models unless otherwise stated)
|Absolute Calibration||± 5 % in air traceable to NBS.|
|Sensitivity||Typically 3 µA per 1000 µmol s-1 m-2 for LI-192SB and 4 µA per 1000 µmol s-1 m-2 for LI-192SA in water.|
|Linearity||Maximum deviation of 1 % up to 10,000 µmol s-1 m-2.|
|Stability||< ± 2 % change over a 1 year period.|
|Response Time||10 µs.|
|Temperature Dependence||± 0.15 % per °C maximum.|
|Cosine Correction||Optimized for both underwater and atmospheric use.|
|Azimuth||< ± 1 % error over 360 ° at 45 ° elevation.|
|Detector||High stability silicon photovoltaic detector (blue enhanced).|
|Sensor Housing||Corrosion resistant metal with acrylic diffuser for both saltwater and freshwater applications. Waterproof to withstand 800 psi (5500 kPa) (560 meters).|
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.
|Power requirements||7 - 20 VDC, 3.5 mA avg., 6 mA pk.|
|Output||0 - 5.0 VDC|
|Output Time Constant||0.1 sec.|
|RMS Noise>||< 1 mV|
|Power-up transient period||< 1 sec.|
|Light Source Wavelength||880 nm|
|Sensing Distance (from windows)||< 5 cm (approx.)|
|Linearity||< 2% deviation 0 - 750 FTU|
|Gain||Sensitivity (mV FTU-1)||Range (FTU)|
** output is non-linear above 750 FTU.
Further details can be found in the manufacturer's specification sheet.
BODC post processing and screening
The data were provided to BODC in ASCII format as .cor files. Positional information on each cast was gathered fom the bottle data files. The data were converted from ASCII format into BODC internal format (QXF) using BODC transfer function 268.
Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor EDSERPLO. EDSERPLO provides a graphical representation of the data so that parameters can be visually checked for innaccuacies. Checks include identifying anomolous data spikes, gaps in the data and values that lie outside of expected limits for the instrument or environment. No data values were edited or deleted so any suspicious data can be viewed and accepted or rejected by the viewer. Flagging was achieved by modification of the associated quality control flag.
Cefas cruise RV Corystes (CO13/04) CTD data document
Originator's Data Processing
The aim of this project was to achieve a better understanding of the dynamics of the circulation processes of the seas around the UK. This would help to characterise the extent and nature of density driven and seasonal jet-like circulation which acts as a direct and rapid pathway for transport of material.
This cruise took place in the North Sea Dogger Bank region. The sampling line followed was the same that had been previously visited in June and August of 1999, 2000 and 2001. This cruise was undertaken in conjunction with 2 other cruises, the Endeavour 12/04 andEndeavour 14/04 . The 3 cruises took place between September - December 2004 in order to describe the gradual alteration of pathways as frontal regions move and revert to a fully mixed and largely wind driven winter regime. This cruise was undertaken between 31st August 2004 and 4th September 2004. A total of 11 CTD casts were performed.
More information on this cruise can be found in the cruise report.
The data were calibrated by Cefas at their laboratory in Lowestoft. Further details of the processing carried out by the orginator are available in the originator's calibration notes.
|Pres||Pressure||Calibrated from deck measurements|
|Temp||Temperature||Calibrated from Platinum resistance thermometers (PRT's) in March 2004|
|Salinity||Salinity||Calibrated from bottle samples using a Guildine salinometer|
|Pot||Potential Temperature||Derived from temperature readings|
|Turb||Turbidity||Calibrated from water samples|
|Sl||Suspended Load||Calibrated from turbidity readings|
|PAR||Photosynthetically Active Radiation||-|
|Chl||Chlorophyll||Calibrated from measured bottle samples Derived from fluorescence measurements|
Cefas project A1225 - North Sea Dogger Bank
This project is aimed at achieving a better understanding of the dynamics of the circulation processes of the seas around the UK. In order to characterise the extent and nature of density driven and seasonal jet-like circulation which acts as a direct and rapid pathway for transport of material. This project consists of three cruises in Autumn 2004: CO13/04, CE12/04 and CE14/04 which aim to examine change over this 2 month period from the warmest, most stratified conditions through to the breakdown period.
The chosen area of interest is the Northern flank of the Dogger Bank along a line that was previously visited in June and August 1999, 2000 and in 2001. In order to identify the structure of the mixing in the bottom region, and for comparisons with models, a thermistor chain and ADCPS will be deployed for the period between the cruises as this will enable the exact timing and nature of breakdown to be indentified. As well as the thermohaline structure the phtyoplankton structure and nutrient uptake will be investigated. With regular samples taken for Isotope analysis. The project aims can be summarised as:
1. To characterise the hydrographic structure associated with the frontal regions and investigate the transport pathways. By use of towed undulating CTDs.
2. Deploy ARGOS drifting buoys to quantify the Lagrangian circulation.
3. Deploy Mooring (ADCP and thermistor chain) to study the mixing processes in the transitional region.
4. Conduct experiments for phytoplankton production both by Nitrogen uptake method and by Carbon14 labelling. (This was not conducted as permission was not obtained for licence despite many months notice).
5. Take samples for Isotope analysis.
A summary of the cruises is shown below.
|Cruise||Departure date||Return date||Numbeer of CTD casts||Track charts|
|CO 13/04||31st Aug 2004||4th Sep 2004||11||Cruise Track|
|CE 12/04||30th Sep 2004||9th Oct 2004||29||Cruise Track|
|CE 14/04||22nd Oct 2004||1st Nov 2004||82||Cruise Track|
|Principal Scientist(s)||Liam Fernand (Centre for Environment, Fisheries and Aquaculture Science Lowestoft Laboratory)|
Complete Cruise Metadata Report is available here
No Fixed Station Information held for the Series
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
|<||Below detection limit|
|>||In excess of quoted value|
|A||Taxonomic flag for affinis (aff.)|
|B||Beginning of CTD Down/Up Cast|
|C||Taxonomic flag for confer (cf.)|
|E||End of CTD Down/Up Cast|
|G||Non-taxonomic biological characteristic uncertainty|
|I||Taxonomic flag for single species (sp.)|
|K||Improbable value - unknown quality control source|
|L||Improbable value - originator's quality control|
|M||Improbable value - BODC quality control|
|O||Improbable value - user quality control|
|0||no quality control|
|2||probably good value|
|3||probably bad value|
|6||value below detection|
|7||value in excess|
|A||value phenomenon uncertain|
|Q||value below limit of quantification|