Metadata Report for BODC Series Reference Number 327039
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 8/1989 CTD Data Documentation
|Area||North Sea North East Coast|
|CTD||Shallow water unit, S/N 47341|
Details of Profiles
Altimeter fitted. Transmissometer fitted. Logging at 1 sample per second -1 (HP 1000).
(a) 1 x 25h anchor stations (no data from 1st dip, station 3)
(b) 3 x 13h anchor stations (no data from 1st dip, station 99, A53)
(c) 40 station CTD grid (no data from station 178)
(d) 16 miscellaneous CTD stations
118 uncorrected data files.
117 corrected data files.
Pressure calibration before and after cruise. Doubts over altimeter data prevented usual comparison between CTD pressure values and height above seabed/water depth, laboratory calibration prior to cruise used to correct CTD pressure values (July 1989).
Temperature calibration of July 1989 used, confirmed by DSRT.
Water samples collected for salinity calibration. Each anchor station had its own salinity correction.
Calculation of %Transmission from logged data T1 follows temperature. Then:
%Trans = 100 - 2*T1 for T1 >50.0
See program listing in this folder. Corrections applied.
From calibration of July 19 no correction necessary.
dT = a*T(ctd)*T(ctd) + B*T(ctd) + c
a = -8.98692e-4
b = 2.8007e-3
c = 2.036e-1
Each of the anchor stations (AS1-AS4) has a unique calibration.
dS = a*S(ctd) + b
- AS1: a = -1.83753e-1 b = 6.124 ( 4- 30)
- AS2: a = 0.0 b = -0.191 ( 69- 83)
- AS3: a = -3.7343e-1 b = 12.679 ( 87-104)
- AS4: a = -2.37015e-1 b = 7.974 (120-137)
The coefficients for the other stations worked during the cruise are as follows:
|Grid stations 139-177:||a = -1.91788e-1 |
b = 6.432
|stations 48- 66:||as for AS1|
|stations 106-110:||as for AS3|
General Data Screening carried out by BODC
BODC screen both the series header qualifying information and the parameter values in the data cycles themselves.
Header information is inspected for:
- Irregularities such as unfeasible values
- Inconsistencies between related information, for example:
- Times for instrument deployment and for start/end of data series
- Length of record and the number of data cycles/cycle interval
- Parameters expected and the parameters actually present in the data cycles
- Originator's comments on meter/mooring performance and data quality
Documents are written by BODC highlighting irregularities which cannot be resolved.
Data cycles are inspected using time or depth series plots of all parameters. Currents are additionally inspected using vector scatter plots and time series plots of North and East velocity components. These presentations undergo intrinsic and extrinsic screening to detect infeasible values within the data cycles themselves and inconsistencies as seen when comparing characteristics of adjacent data sets displaced with respect to depth, position or time. Values suspected of being of non-oceanographic origin may be tagged with the BODC flag denoting suspect value; the data values will not be altered.
The following types of irregularity, each relying on visual detection in the plot, are amongst those which may be flagged as suspect:
- Spurious data at the start or end of the record.
- Obvious spikes occurring in periods free from meteorological disturbance.
- A sequence of constant values in consecutive data cycles.
If a large percentage of the data is affected by irregularities then a Problem Report will be written rather than flagging the individual suspect values. Problem Reports are also used to highlight irregularities seen in the graphical data presentations.
Inconsistencies between the characteristics of the data set and those of its neighbours are sought and, where necessary, documented. This covers inconsistencies such as the following:
- Maximum and minimum values of parameters (spikes excluded).
- The occurrence of meteorological events.
This intrinsic and extrinsic screening of the parameter values seeks to confirm the qualifying information and the source laboratory's comments on the series. In screening and collating information, every care is taken to ensure that errors of BODC making are not introduced.
No Project Information held for the Series
|Principal Scientist(s)||Paul A Gurbutt (Ministry of Agriculture, Fisheries and Food Lowestoft Fisheries 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|