Metadata Report for BODC Series Reference Number 184018
No Problem Report Found in the Database
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."
Guildline 8770 CTD profiling system and 8709 probe
The Guildline 8770 is a portable ocean profiling system comprising a probe (model 8709), control unit and winch. Three versions of the probe are available: standard, Artic and batfish. The differences between the versions lie in numbers and types of connectors, and the existence of a protective cage (not present in the batfish version). The probe has a nominal drop rate of 1 ms-1 and a pressure rating of 1000 dbar.
The probe includes a resistance thermometer temperature sensor, a strain gauge pressure sensor, a conductivity cell, a temperature-compensated polarographic dissolved oxygen sensor and a combination pH sensor incorporating a glass measuring electrode and a calomel reference electrode. The probe digitises all measurements, and phase encodes and transmits the data to the control unit.
|Parameter||Range||Accuracy (180 days)||Display Resolution||Response time|
|Depth||0 to 1000 dbar|| |
Linearity: ± 0.5%
Hysteresis: ± 0.25%
Zero offset: ± 1%
Sensitivity error: ± 1%
|0.1 dbar||< 1 msec|
|Temperature||-3 to 38.99°C||± 0.02°C||0.01°C||60 msec|
|Conductivity ratio||0.001 to 1.6||± 0.0004||0.0002||60 msec|
|Salinity (calculated)||0.1 to 40 ppt||± 0.04 ppt||0.01 ppt|
6 to 9
2 to 12
|0.01||30 sec to 90% for pH 6 or 10°C change|
|Dissolved Oxygen (calculated)||0 to 15 ppm||± 0.5 ppm (for 90 days)||0.01 ppm|| |
5 sec to 90% for a change in oxygen only
3 min to 50% for a 10°C change in temperature
10 min to 90% for a 10°C change in temperature
Further details can be found in the manufacturer's specification sheet.
RV Corystes Cruise 6/88 CTD Data Documentation
Documentation for CTD data collected on R.V. Corystes Cruise 6/88 (Aug - Sep 1988) by the Ministry of Agriculture, Fisheries and Food, Fisheries Laboratory, Lowestoft, Suffolk, UK, under the direction of K. Medler.
The instrument used was a Guildline Model 8770 CTD. The system consisted of a probe and control unit which measured (or calculated) pressure, conductivity ratio, temperature and salinity. The conductivity sensor is an electrode mounted in pyrex glass, the pressure sensor is a strain gauge element in a four arm resistance bridge network and the temperature sensor is a copper resistance element in a stainless steel tube. The probe electronically measures the parameters and sends the data to the control unit after digitising the results.
The control unit converts the data to binary format, displays the results, has analog output for chart recording and allows the data to be recorded on audio cassette. This latter facility is usually a precaution against information loss since data are logged (at 1 sample per second) on either a Hewlett Packard mini computer or an Apricot microcomputer. Salinity is calculated by a microprocessor within the system, the algorithm used is that for the Practical Salinity Scale.
The CTD is mounted on a General Oceanics multisampler fitted with Niskin bottles. This enables the data to be logged whilst the water sample is being collected. Attaching thermometers to the Niskin bottles allows comparison to be made between reversing thermometers and the CTD temperature sensor. An altimeter has been fitted to the multisampler, this allows a comparison to be made with the pressure calibration.
The pressure sensor was corrected after calibration with a dead weight tester.
Temperature sensor corrected after laboratory calibration with platinum resistance thermometers. The platinum resistance thermometers were set by a triple point cell calibrated at the National Physical Laboratory. Reversing thermometers were used to validate the laboratory calibrations.
The calculated salinity was corrected after comparison with the salinity of water samples collected during the cruise. In addition, a precision decade box was used to check the conductivity sensor.
Data are logged every one second. Since the lowering rate is usually less than one metre per second, values are often recorded at between 0.2 and 0.4 decibar intervals. These data have not been averaged, however they have been plotted to identify spurious readings. Estimates of density were also used to help identify suspect values, but in view of the limited accuracy of the instrument and because the water column is well mixed it is inevitable that some density inversions will exist in the data.
No Project Information held for the Series
|Principal Scientist(s)||Steven M Rowlatt (Ministry of Agriculture, Fisheries and Food Burnham 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|