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Metadata Report for BODC Series Reference Number 176995

Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
Guildline Model 8770 Digital CTD  CTD; water temperature sensor
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization Ministry of Agriculture, Fisheries and Food Lowestoft Fisheries Laboratory (now Centre for Environment, Fisheries and Aquaculture Science Lowestoft Laboratory)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) -

Data Identifiers

Originator's Identifier 9/86CI31 D
BODC Series Reference 176995

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1986-11-14 14:25
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -

Spatial Co-ordinates

Latitude 54.49330 N ( 54° 29.6' N )
Longitude 3.70500 W ( 3° 42.3' W )
Positional Uncertainty 0.1 to 0.5 n.miles
Minimum Sensor or Sampling Depth 9.71 m
Maximum Sensor or Sampling Depth 19.42 m
Minimum Sensor or Sampling Height 5.57 m
Maximum Sensor or Sampling Height 15.29 m
Sea Floor Depth 25.0 m
Sea Floor Depth Source -
Sensor or Sampling Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor or Sampling Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface
Sea Floor Depth Datum Instantaneous - Depth measured below water line or instantaneous water body surface


BODC CODERankUnitsTitle
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALPR011DimensionlessPractical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPST011Degrees CelsiusTemperature of the water body by CTD or STD

Definition of Rank

  • Rank 1 is a one-dimensional parameter
  • Rank 2 is a two-dimensional parameter
  • Rank 0 is a one-dimensional parameter describing the second dimension of a two-dimensional parameter (e.g. bin depths for moored ADCP data)

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

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

± 0.05

± 0.1

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 Cirolana 9/86 CTD Data Documentation


Documentation for CTD data collected on R.V. Cirolana Cruise 9/86 (November 1986) 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 was an electrode mounted in pyrex glass, the pressure sensor was a strain gauge element in a four arm resistance bridge network and the temperature sensor was a copper resistance element in a stainless steel tube. The probe electronically measured the parameters and sent the data to the control unit after digitising the results.

The control unit converted the data to binary format, displayed the results, had analog output for chart recording and allowed the data to be recorded on audio cassette. This latter facility was usually a precaution against information loss since data were logged (at 1 sample per second) on either a Hewlett Packard mini computer or an Apricot microcomputer. Salinity was calculated by a microprocessor within the system. The algorithm used was not that for the Practical Salinity Scale, but gave comparable results.

The CTD was mounted on a General Oceanics multisampler fitted with Niskin bottles. This enabled the data to be logged whilst the water sample was being collected. Attaching thermometers to the Niskin bottles allowed comparison to be made between reversing thermometers and the CTD temperature sensor. An altimeter had been fitted to the multisampler. This allowed a comparison to be made with the pressure sensor.



The pressure sensor was corrected after calibration with a dead weight tester.


The temperature sensor was 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.


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 Processing

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.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information


Cruise Name CIR9/86
Departure Date 1986-11-03
Arrival Date 1986-11-23
Principal Scientist(s)Dennis S Woodhead (Ministry of Agriculture, Fisheries and Food Lowestoft Fisheries Laboratory)
Ship RV Cirolana

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:

Flag Description
Blank Unqualified
< 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.)
D Thermometric depth
E End of CTD Down/Up Cast
G Non-taxonomic biological characteristic uncertainty
H Extrapolated value
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
N Null value
O Improbable value - user quality control
P Trace/calm
Q Indeterminate
R Replacement value
S Estimated value
T Interpolated value
U Uncalibrated
W Control value
X Excessive difference

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Flag Description
0 no quality control
1 good value
2 probably good value
3 probably bad value
4 bad value
5 changed value
6 value below detection
7 value in excess
8 interpolated value
9 missing value
A value phenomenon uncertain
B nominal value
Q value below limit of quantification