Metadata Report for BODC Series Reference Number 316460


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Bissett-Bermann 9040 CTD system  CTD; water temperature sensor; salinity sensor
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization Dunstaffnage Marine Laboratory (now Scottish Association for Marine Science)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) -
 

Data Identifiers

Originator's Identifier CH81/91/036
BODC Series Reference 316460
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1991-07-05 01:11
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval -
 

Spatial Co-ordinates

Latitude 57.38330 N ( 57° 23.0' N )
Longitude 13.74670 W ( 13° 44.8' W )
Positional Uncertainty Unspecified
Minimum Sensor or Sampling Depth 10.2 m
Maximum Sensor or Sampling Depth 153.22 m
Minimum Sensor or Sampling Height 2.78 m
Maximum Sensor or Sampling Height 145.8 m
Sea Floor Depth 156.0 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
 

Parameters

BODC CODERankUnitsTitle
PRESPR011DecibarsPressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected 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

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."


Narrative Documents

Bissett-Bermann 9040 Conductivity Temperature and Depth

The basic configuration of the B-B 9040 CTD incorporates pressure, temperature and conductivity sensors which could be logged digitally. This system also made it possible to derive other parameters, such as salinity, depth and sound velocity.

The instrument was versatile and it was possible to attach a dissolved oxygen sensor or to change the CTD housing, allowing it to obtain data from deeper layers in the water column. The accuracy for salinity is ±0.02 ppt , and ±0.02°C for temperature.

This instrument was also known as the Plessey 9040.

RRS Challenger Cruise 81/91 CTD Data Documentation

Introduction

Documentation for the CTD data collected on RRS Challenger 81/91 (July 1991) by the Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland, UK, under the direction of D. J. Ellett.

Instrumentation

The instrument used was a Bissett Berman 9040 CTD system and the data were logged on a Hewlett Packard 9820 and stored in an integer format. Instrument lowering and raising speeds were between 0.5m/s and 1m/s. An acoustic pinger was placed above the CTD to give an accurate depth measurement, this could then be used to check the CTD pressure calibration. An NIO bottle with reversing thermometers was placed above the pinger, within 2m of the CTD system. A bottle sample was taken at the bottom of the cast providing the temperature and salinity are uniform at that point. If large temperature or salinity gradients were present then the bottle sample was triggered at a suitable site on the upcast. A surface salinity sample was also taken at the start of the dip.

Calibration and Data Quality

The CTD was not calibrated in the laboratory. The manufacturer's calibration was used and water samples taken to check the calibration and apply corrections where necessary.

Temperature

The manufacturer's calibration was used to convert the raw data to to physical units using the equation below:

Temperature (°C) = (10**6/Pt -2238.68/55.84)
where Pt is the temperature period in microseconds

These values were then plotted against the water bottle (i.e. reversing thermometer) temperatures and a regression line fitted to the data such that:

Temperature(WB) = m x Temperature(CTD) + c

Then the regression coefficients (m and c) were applied to correct the CTD temperature data - these are given in the table below.

Conductivity

The manufacturer's calibration was used to convert the raw data to to physical units using the equation below:

Conductivity (mmho/cm) = (10**6/Pc - 4995)/58.12 + 10
where Pc is the conductivity period in microseconds

The water bottle salinities and corrected CTD temperatures were used to calculate the water bottle conductivity values. These values were then plotted against the CTD conductivities and a regression line fitted to the data such that:

Conductivity(WB) = m x Conductivity(CTD) + c

Then the regression coefficients were applied to correct the CTD conductivity data - these are given in the table below.

Pressure

The depths from the acoustic pinger were noted where the bottle samples were taken and then used to check the calibration of the pressure sensor - unless calibration values were available from the reversing thermometers. The equation below was used to convert the pressure period to physical units.

Pressure = (10**6/Pd - 9712)/0.26267
where Pd is the pressure period in microseconds

A regression fit was carried out using the calibration values and the slope and intercept determined. The pressure values could then be corrected using:

Pressure (CORR) = m x Pressure(CTD) + c

The fit of the CTD data to the water bottle calibration data is given in the table below:

Variable Slope (m) Intercept (c)
Temperature (°C) 1.0159843 -0.175004
Conductivity (mmho/cm) 1.0155348 -0.460903
Pressure (dbar) 1.0016226 19.705484

Data Processing

Obvious wild points were edited out of the calibration file and the calibration programs run to obtain values for the slopes and intercepts for temperature, pressure and conductivity. These were then applied to the uncalibrated data. Conductivities were converted to conductivity ratios and then converted to salinities using UNESCO recommended routines and sigma-t was calculated. The data values were then sieved to ensure a minimum separation between pressure values of 1 dbar. The data were then visually inspected and major spikes flagged.

Reference

Fofonoff, N.P. and Millard Jr., R.C. (1983).
Algorithms for the computation of fundamental properties of sea water. UNESCO Technical Paper on Marine Science 44.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name CH81
Departure Date 1991-07-01
Arrival Date 1991-07-08
Principal Scientist(s)David J Ellett (Dunstaffnage Marine Laboratory)
Ship RRS Challenger

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameDML Malin Head Line
CategoryOffshore route/traverse

DML Malin Head Line

The DML Malin Head Line is a survey section crossing the Rockall Trough, west of Scotland. The section starts close to the outcrop of Rockall and heads in a south easterly direction towards Malin Head (County Donegal, Republic of Ireland). The final station is at the shelf edge. The section comprises 15 fixed STD/CTD stations, which were established as part of routine monitoring work west of Scotland by Dunstaffnage Marine Laboratory (DML). The DML Malin Head Line was occupied between the mid 1970s and mid 1990s.

Map of standard DML Malin Head Line STD/CTD Stations

BODC image

Map produced using the GEBCO Digital Atlas.

The white triangles indicate the nominal positions of each standard Malin Head Line Station. The black circle indicates the location of Rockall.

Nominal station details

DML Malin Head Line Stations

Station Nominal latitude Nominal longitude Approx.
depth (m)
Comment
CS 55° 47.0' N 09° 16.0' W 160  
DS 55° 52.0' N 09° 27.0' W 1000  
ES 55° 56.0' N 09° 38.0' W 1550  
FS 56° 00.0' N 09° 50.0' W 2050  
GS 56° 07.0' N 10° 12.0' W 2134  
HS 56° 15.0' N 10° 33.0' W 2230  
IS 56° 26.0' N 11° 03.0' W 2608  
JS 56° 37.0' N 11° 33.0' W 2550  
KS 56° 47.0' N 12° 03.0' W 2320  
LS 56° 58.0' N 12° 33.0' W 2024  
MS 57° 06.0' N 12° 56.0' W 1600  
NS 57° 10.0' N 13° 07.0' W 1000  
OS 57° 13.0' N 13° 15.0' W 250  
PS 57° 18.0' N 13° 30.0' W 200  
QS 57° 23.0' N 13° 45.0' W 155  

Related Fixed Station activities are detailed in Appendix 1

Fixed Station Information

Station NameDML Malin Head Line - Station QS
CategoryOffshore location
Latitude57° 23.00' N
Longitude13° 45.00' W
Water depth below MSL155.0 m

DML Station QS

Station QS is one of 15 fixed STD/CTD stations crossing the Rockall Trough between the outcrop of Rockall and the shelf edge to the south east. The station was established by scientists at Dunstaffnage Marine Laboratory (DML).

Related Fixed Station activities are detailed in Appendix 2


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
Q value below limit of quantification

Appendix 1: DML Malin Head Line

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
314207CTD or STD cast1975-03-10 13:42:0056.7833 N, 12.05 WRRS Challenger CH3/75
314220CTD or STD cast1975-03-11 02:30:0057.1167 N, 12.9 WRRS Challenger CH3/75
314232CTD or STD cast1975-03-11 10:45:0057.1667 N, 13.1167 WRRS Challenger CH3/75
314244CTD or STD cast1975-03-11 11:52:0057.2167 N, 13.25 WRRS Challenger CH3/75
314256CTD or STD cast1975-03-11 13:50:0057.2667 N, 13.4833 WRRS Challenger CH3/75
314268CTD or STD cast1975-03-11 15:21:0057.3833 N, 13.75 WRRS Challenger CH3/75
89415CTD or STD cast1975-07-07 02:10:0057.37 N, 13.7066 WRRS Challenger CH10A/75
89427CTD or STD cast1975-07-07 03:30:0057.3116 N, 13.54 WRRS Challenger CH10A/75
89439CTD or STD cast1975-07-07 05:35:0057.22 N, 13.2783 WRRS Challenger CH10A/75
89440CTD or STD cast1975-07-07 06:35:0057.1766 N, 13.1533 WRRS Challenger CH10A/75
89452CTD or STD cast1975-07-07 08:20:0057.1 N, 12.9333 WRRS Challenger CH10A/75
89464CTD or STD cast1975-07-07 12:22:0056.9766 N, 12.5083 WRRS Challenger CH10A/75
89476CTD or STD cast1975-07-07 15:30:0056.7833 N, 12.0433 WRRS Challenger CH10A/75
89488CTD or STD cast1975-07-07 20:42:0056.6066 N, 11.5166 WRRS Challenger CH10A/75
89519CTD or STD cast1975-07-08 05:20:0056.2233 N, 10.5366 WRRS Challenger CH10A/75
89520CTD or STD cast1975-08-29 19:35:0056.6183 N, 11.55 WRRS Challenger CH12A/75
89532CTD or STD cast1975-08-29 23:05:0056.4333 N, 11.0483 WRRS Challenger CH12A/75
89544CTD or STD cast1975-08-30 04:05:0056.2416 N, 10.5666 WRRS Challenger CH12A/75
89556CTD or STD cast1975-08-30 07:11:0056.1166 N, 10.2 WRRS Challenger CH12A/75
89568CTD or STD cast1975-08-30 10:03:0056.0033 N, 9.8316 WRRS Challenger CH12A/75
89581CTD or STD cast1975-08-30 12:06:0055.9366 N, 9.6333 WRRS Challenger CH12A/75
89593CTD or STD cast1975-08-30 16:35:0055.7833 N, 9.2667 WRRS Challenger CH12A/75
266049CTD or STD cast1989-05-07 16:08:0056.9666 N, 12.5833 WRV Lough Foyle LF1/89
266050CTD or STD cast1989-05-08 03:02:0056.0 N, 9.8333 WRV Lough Foyle LF1/89
266062CTD or STD cast1989-05-08 04:53:0055.9333 N, 9.6333 WRV Lough Foyle LF1/89
266074CTD or STD cast1989-05-08 06:21:0055.8666 N, 9.45 WRV Lough Foyle LF1/89
266086CTD or STD cast1989-05-08 07:44:0055.7833 N, 9.2666 WRV Lough Foyle LF1/89
317832CTD or STD cast1989-08-07 05:46:0055.775 N, 9.2717 WRV Lough Foyle LF2/89
382708CTD or STD cast1991-02-28 16:31:0056.9683 N, 12.5533 WRRS Challenger CH75B
382721CTD or STD cast1991-03-01 02:12:0056.435 N, 11.055 WRRS Challenger CH75B
382733CTD or STD cast1991-03-01 10:20:0055.9333 N, 9.6317 WRRS Challenger CH75B
382745CTD or STD cast1991-03-01 12:34:0055.8667 N, 9.45 WRRS Challenger CH75B
382757CTD or STD cast1991-03-01 14:29:0055.7833 N, 9.2667 WRRS Challenger CH75B
316472CTD or STD cast1991-07-05 02:40:0057.3 N, 13.5 WRRS Challenger CH81
316484CTD or STD cast1991-07-05 04:12:0057.2167 N, 13.2483 WRRS Challenger CH81
316496CTD or STD cast1991-07-05 05:10:0057.17 N, 13.11 WRRS Challenger CH81
316503CTD or STD cast1991-07-05 06:54:0057.1033 N, 12.93 WRRS Challenger CH81
316515CTD or STD cast1991-07-05 10:06:0056.9817 N, 12.55 WRRS Challenger CH81
316539CTD or STD cast1991-07-05 15:48:0056.7833 N, 12.0467 WRRS Challenger CH81
316540CTD or STD cast1991-07-05 19:33:0056.6167 N, 11.5517 WRRS Challenger CH81
316552CTD or STD cast1991-07-05 23:30:0056.435 N, 11.0517 WRRS Challenger CH81
316564CTD or STD cast1991-07-06 04:38:0056.25 N, 10.5417 WRRS Challenger CH81
316576CTD or STD cast1991-07-06 07:39:0056.1167 N, 10.2017 WRRS Challenger CH81
316588CTD or STD cast1991-07-06 10:48:0056.0 N, 9.835 WRRS Challenger CH81
316607CTD or STD cast1991-07-06 13:39:0055.935 N, 9.6317 WRRS Challenger CH81
386980CTD or STD cast1992-10-02 23:18:0055.87 N, 9.45 WRRS Challenger CH97
389142CTD or STD cast1994-05-01 09:35:0056.4333 N, 11.05 WRRS Challenger CH112
391029CTD or STD cast1994-08-19 19:40:0057.1 N, 12.9333 WRRS Challenger CH114
391030CTD or STD cast1994-08-20 00:30:0056.7835 N, 12.0507 WRRS Challenger CH114
391042CTD or STD cast1994-08-20 06:14:0056.4333 N, 11.05 WRRS Challenger CH114

Appendix 2: DML Malin Head Line - Station QS

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
314268CTD or STD cast1975-03-11 15:21:0057.3833 N, 13.75 WRRS Challenger CH3/75
89415CTD or STD cast1975-07-07 02:10:0057.37 N, 13.7066 WRRS Challenger CH10A/75