Metadata Report for BODC Series Reference Number 326534
Metadata Summary
Problem Reports
Data Access Policy
Narrative Documents
Project Information
Data Activity or Cruise Information
Fixed Station Information
BODC Quality Flags
SeaDataNet Quality Flags
Metadata Summary
Data Description |
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Data Identifiers |
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Time Co-ordinates(UT) |
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Parameters |
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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.
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 8/1989 CTD Data Documentation
Date | July 1989 |
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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.
Calibration details
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.
Transmission
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.
Pressure
From calibration of July 19 no correction necessary.
Temperature
dT = a*T(ctd)*T(ctd) + B*T(ctd) + c
where:
a = -8.98692e-4
b = 2.8007e-3
c = 2.036e-1
Salinity
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.
Project Information
No Project Information held for the Series
Data Activity or Cruise Information
Cruise
Cruise Name | COR8/89 |
Departure Date | 1989-07-14 |
Arrival Date | 1989-07-27 |
Principal Scientist(s) | Paul A Gurbutt (Ministry of Agriculture, Fisheries and Food Lowestoft Fisheries 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 |
B | nominal value |
Q | value below limit of quantification |