Metadata Report for BODC Series Reference Number 340619


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Guildline Model 8705 Digital CTD  salinity 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) Joint Nutrient Study I (JoNuS)
 

Data Identifiers

Originator's Identifier CO3A/92/63
BODC Series Reference 340619
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1992-02-20 17:31
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 decibars
 

Spatial Co-ordinates

Latitude 53.67020 N ( 53° 40.2' N )
Longitude 0.23080 W ( 0° 13.8' W )
Positional Uncertainty Unspecified
Minimum Sensor Depth 1.0 m
Maximum Sensor Depth 11.9 m
Minimum Sensor Height 0.1 m
Maximum Sensor Height 11.0 m
Sea Floor Depth 12.0 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 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:

  1. Thermometer differences >0.02 were discounted.

  2. 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:

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:

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:

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:

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