Metadata Report for BODC Series Reference Number 340761
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
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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 8705 CTD
The 8705 CTD is a conductivity-temperature-pressure profiler designed for marine applications down to depths of 6000 m. The instrument includes an anodised aluminium tube with a steel cage to protect the temperature and conductivity sensors and a urethane cap to protect the pressure sensor.
Specifications
Parameter | Range | Accuracy | Resolution | Stability | Response time |
---|---|---|---|---|---|
Pressure | 0 to 6000 dbar | ± 0.15% of full range | ± 0.01% of full range | - | < 50 ms |
Temperature | -2 to 30 °C | ± 0.005 °C | ± 0.0005 °C | ± 0.002 °C over 30 days ± 0.0025°C over 6 months | < 50 ms |
Conductivity * | 100 ppm to 40 ppt | ± 0.005 ppt | ± 0.001 ppt | ± 0.002 ppt over 6 months | < 50 ms |
* Conductivity specifications are given in terms of equivalent salinity
Further details can be found in the manufacturer's specification sheet.
RV Corystes Cruise 3A/92 CTD Data Documentation
Instrumentation
The CTD used was S/N 45056.
Sampling Protocol
A total of 88 valid profiles were collected during this cruise. Reversing thermometers were fitted to the Niskin bottles being used to collect samples. A total of 126 pairs of thermometer readings were taken, together with 166 pairs of salinity samples.
Calibration
Not all the calibration data collected were used to calibrate the CTD for the following reasons:
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Thermometer differences >0.02 were discounted.
-
It was apparent from inspection of differences between mean salinity samples and salinity values from the CTD that there were some large discrepancies. Consequently, only salinity values from bottom samples excluding those from stations 55-67 (Humber anchor station) were used to derive calibration coefficients for the CTD.
Pressure
The pressure sensor was corrected using the laboratory calibration of March 1992 at T = 6 °C.
P(cor) = P(ctd) - 1.6
Temperature
The temperature sensor was corrected using the laboratory calibration of March 1992.
T(cor) = T(ctd) + 0.011
It is assumed that the thermometer temperatures are accurate to 0.02 °C and the CTD to 0.01 °C, so that differences within 0.03 °C are acceptable. Fig. 1 shows the comparison between reversing thermometer and uncorrected CTD temperatures. Out of 126 sets of values only 11 were outside the acceptable range. The mean differences of those used was 0.009 °C.
Salinity
The salinity sensor was calibrated using the equation:
CR(cor) = CR(ctd)x[a x T(cor) + b x P(cor) + c]
where:
a = -0.807779e-4
b = -0.274751e-5
c = 0.100025e+1
The rms difference between salinometer and CTD salinity was 0.008.
Fig. 2 shows the distribution of differences between salinity samples and CTD salinity values before and after the application of the calibration.
Fig. 3 shows the ratio between the CTD conductivity and water samples conductivity before applying the correction. Note the poor quality for Stations 55 to 67, from the Humber Estuary.
Fig. 4 shows the differences between the water sample salinity and the uncorrected CTD value, after removal of unsuitable calibration data.
Fig. 5 shows similar, but after calibration of the CTD sensors.
Stations Worked
The general distribution of the stations on this cruise was:
Stations | Location |
---|---|
1-46, 140, 142 | North Sea |
55-67 | Humber (Killingholme) Anchor |
72-83, 107-112 | Humber to Wash offshore |
85-101, 113-126 | The Wash |
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
Joint Nutrient Study I (JoNuS)
Concerns by the scientific community about the impact of nutrient inputs to the sea; a lack of information on inputs from the UK and on the spatial and temporal distribution and cycling of nutrients in UK waters provided the impetus for the JoNuS project.
The project sought to quantify the input of nitrogen, phosphorus and silicon from UK estuaries to the North Sea through a good understanding of the estuarine processes that control the flow of these nutrients. It focussed on the Great Ouse/Wash and the Humber outflows. Its specific objectives were:
- To measure the fluxes of nutrient elements (N, P, Si) through selected major estuaries on a quantitative annual basis in order to determine the net input to the sea resulting from gross river inputs.
- To quantify the processes controlling the fluxes of nutrients through estuaries.
The Centre for Environment, Fisheries and Aquaculture Science (CEFAS) hosted the project, which involved scientists from CEFAS, the University of East Anglia, the University of Essex, the Plymouth Marine Laboratory and the National Rivers Authority (now the Environment Agency). It was funded by the then Ministry of Agriculture, Fisheries and Food (MAFF) and the Department of Environment, now the Department of Environment, Food and Rural Affairs (Defra).
The project ran from April 1990 to March 1995, with marine field data collection between May 1990 and December 1993. Data collection involved ship based surveys which were complemented by estuarine transects and specific process studies.
Initially, the surveys were on a quarterly basis up to October 1992, however monthly surveys were carried out during 1993. During this intensive survey period, the programme focused on the Great Ouse/Wash; with a continuing, but lower level, of activity devoted to the Humber. An additional multi-project cruise, carried out in January 1995, also complemented the JoNuS data set. Further details of the JoNuS I cruises are provided below:
Cruise identifier | Date | Comments |
---|---|---|
RV Cirolana CIR5/90 | 1990-05-03 - 1990-05-20 | None |
RV Cirolana CIR7/90 | 1990-07-06 - 1990-07-25 | None |
RV Cirolana CIR10/90 | 1990-10-29 - 1990-11-16 | None |
Seeker 2/90 | 1990-10-29 - 1990-11-03 | Sediment and water sample collection only |
RV Cirolana CIR1/91 | 1991-01-05 - 1991-01-23 | None |
RV Cirolana CIR4/91 | 1991-04-12 - 1991-05-02 | None |
RV Cirolana CIR8A/91 | 1991-09-25 - 1991-10-09 | None |
RV Corystes (88-04) COR1/92 | 1992-01-03 - 1992-01-20 | None |
RV Corystes (88-04) COR3A/92 | 1992-02-14 - 1992-02-26 | None |
RV Cirolana CIR8/92 | 1992-07-29 - 1992-08-06 | None |
RV Corystes (88-04) COR11/92 | 1992-09-28 - 1992-10-12 | None |
RV Cirolana CIR1/93 | 1993-01-08 - 1993-01-22 | None |
RV Corystes (88-04) COR2A/93 | 1993-02-03 - 1993-02-07 | None |
RV Corystes (88-04) COR2C/93 | 1993-02-18 - 1993-02-24 | None |
RV Corystes (88-04) COR5A/93 | 1993-05-04 - 1993-05-10 | None |
RV Corystes (88-04) COR6A/93 | 1993-06-08 - 1993-06-14 | None |
RV Cirolana CIR7B/93 | 1993-07-26 - 1993-08-02 | None |
RV Corystes (88-04) COR9/93 | 1993-08-20 - 1993-08-26 | None |
RV Cirolana CIR9B/93 | 1993-09-30 - 1993-10-11 | None |
RV Corystes (88-04) COR13/93 | 1993-12-15 - 1993-12-21 | None |
RV Cirolana CIR1/95 | 1995-01-06 - 1995-01-31 | None |
Data Activity or Cruise Information
Cruise
Cruise Name | COR3A/92 |
Departure Date | 1992-02-14 |
Arrival Date | 1992-02-26 |
Principal Scientist(s) | Stephen James Malcolm (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 |