Metadata Report for BODC Series Reference Number 182337


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
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
Project(s) -
 

Data Identifiers

Originator's Identifier 6/88CO2317
BODC Series Reference 182337
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1988-09-05 04:30
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 54.98500 N ( 54° 59.1' N )
Longitude 1.34660 W ( 1° 20.8' W )
Positional Uncertainty 0.1 to 0.5 n.miles
Minimum Sensor Depth 1.29 m
Maximum Sensor Depth 20.71 m
Minimum Sensor Height 5.28 m
Maximum Sensor Height 24.71 m
Sea Floor Depth 26.0 m
Sensor Distribution Variable common depth - All sensors are grouped effectively at the same depth, but this depth varies significantly during the series
Sensor 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
 

Parameters

BODC CODE Rank Units Short Title Title
PRESPR01 1 Decibars Pres_Z Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level
PSALPR01 1 Dimensionless P_sal Practical salinity of the water body by conductivity cell and computation using UNESCO 1983 algorithm
TEMPST01 1 Degrees Celsius WC_temp_CTD Temperature 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

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.


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.

Specifications

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  
pH

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 Corystes Cruise 6/88 CTD Data Documentation

Introduction

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.

Instrumentation

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.

Calibration

Pressure

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

Temperature

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.

Salinity

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

Cruise Name COR6/88
Departure Date 1988-08-31
Arrival Date 1988-09-13
Principal Scientist(s)Steven M Rowlatt (Ministry of Agriculture, Fisheries and Food Burnham Laboratory)
Ship RV Corystes

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