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Metadata Report for BODC Series Reference Number 342823

Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
Neil Brown MK3 CTD  CTD; water temperature sensor; salinity sensor; dissolved gas sensors
SeaTech transmissometer  transmissometers
Chelsea Technologies Group Aquatracka fluorometer  fluorometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator -
Originating Organization University of Wales, Bangor School of Ocean Sciences (now Bangor University School of Ocean Sciences)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) ECTZ

Data Identifiers

Originator's Identifier IP9/91/099
BODC Series Reference 342823

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1991-11-03 13:10
End Time (yyyy-mm-dd hh:mm) 1991-11-03 13:19
Nominal Cycle Interval 2.0 decibars

Spatial Co-ordinates

Latitude 28.86670 N ( 28° 52.0' N )
Longitude 15.55000 W ( 15° 33.0' W )
Positional Uncertainty Unspecified
Minimum Sensor or Sampling Depth 2.98 m
Maximum Sensor or Sampling Depth 399.9 m
Minimum Sensor or Sampling Height -
Maximum Sensor or Sampling Height -
Sea Floor Depth -
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 -


BODC CODERankUnitsTitle
ATTNMR011per metreAttenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
CNDCPR011Siemens per metreElectrical conductivity of the water body by in-situ conductivity cell
CPHLPR011Milligrams per cubic metreConcentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer
POPTDR011PercentTransmittance (red light wavelength) per 25cm of the water body by 25cm path length red light transmissometer
PRESPR011DecibarsPressure (spatial coordinate) exerted by the water body by profiling pressure sensor and correction to read zero at sea level
PSALST011DimensionlessPractical salinity of the water body by CTD 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

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

Neil Brown MK3 CTD

The Neil Brown MK3 conductivity-temperature-depth (CTD) profiler consists of an integral unit containing pressure, temperature and conductivity sensors with an optional dissolved oxygen sensor in a pressure-hardened casing. The most widely used variant in the 1980s and 1990s was the MK3B. An upgrade to this, the MK3C, was developed to meet the requirements of the WOCE project.

The MK3C includes a low hysteresis, titanium strain gauge pressure transducer. The transducer temperature is measured separately, allowing correction for the effects of temperature on pressure measurements. The MK3C conductivity cell features a free flow, internal field design that eliminates ducted pumping and is not affected by external metallic objects such as guard cages and external sensors.

Additional optional sensors include pH and a pressure-temperature fluorometer. The instrument is no longer in production, but is supported (repair and calibration) by General Oceanics.


These specification apply to the MK3C version.

Pressure Temperature Conductivity

6500 m

3200 m (optional)

-3 to 32°C 1 to 6.5 S cm-1

0.0015% FS

0.03% FS < 1 msec


0.003°C < 30 msec

0.0001 S cm-1

0.0003 S cm-1 < 30 msec

Further details can be found in the specification sheet.

Aquatracka fluorometer

The Chelsea Instruments Aquatracka is a logarithmic response fluorometer. It uses a pulsed (5.5 Hz) xenon light source discharging between 320 and 800 nm through a blue filter with a peak transmission of 420 nm and a bandwidth at half maximum of 100 nm. A red filter with sharp cut off, 10% transmission at 664 nm and 678 nm, is used to pass chlorophyll-a fluorescence to the sample photodiode.

The instrument may be deployed either in a through-flow tank, on a CTD frame or moored with a data logging package.

Further details can be found in the manufacturer's specification sheet.

SeaTech Transmissometer


The transmissometer is designed to accurately measure the the amount of light transmitted by a modulated Light Emitting Diode (LED) through a fixed-length in-situ water column to a synchronous detector.


  • Water path length: 5 cm (for use in turbid waters) to 1 m (for use in clear ocean waters).
  • Beam diameter: 15 mm
  • Transmitted beam collimation: <3 milliradians
  • Receiver acceptance angle (in water): <18 milliradians
  • Light source wavelength: usually (but not exclusively) 660 nm (red light)


The instrument can be interfaced to Aanderaa RCM7 current meters. This is achieved by fitting the transmissometer in a slot cut into a customized RCM4-type vane.

A red LED (660 nm) is used for general applications looking at water column sediment load. However, green or blue LEDs can be fitted for specilised optics applications. The light source used is identified by the BODC parameter code.

Further details can be found in the manufacturer's Manual.

RV Ignat Pavlyuchenkov (Oct-Nov 1991) CTD Data Documentation


Documentation for the CTD data collected on RV Ignat Pavlyuchenkov (October - November 1991) by the School of Ocean Sciences, University of Wales, Bangor, under the direction of E.D. Barton.

This cruise formed part of EU MAST Project 0031 - European Coastal Transition Zone, Islas Canarias, with partners from the University of Wales, Bangor, UK, Universidad de Las Palmas de Gran Canarias, Spain, Centro Oceanografico de Canarias, Spain and Centro Comune di Ricerca, Ispra, Italy.


Throughout the cruise period most of the equipment performed well and only minor problems occurred. The only major difficulty was in relation to the CTD which was initially being used (known as the 'Russian CTD'); the conductivity sensor of which was accidentally damaged. Thus, the entire CTD system was replaced by the one taken aboard as part of the University of Wales, Bangor/ Research Vessel Services (UWB/RVS). The equipment of the 'Russian' and 'UWB/ RVS' CTD systems was comparable. Both included Neil Brown CTD Mark III units, fluorometer (Sea-Tech 57S and Chelsea Instruments respectively), 25cm Sea-Tech transmissometer, and a Rosette sampler of 24 bottles and 12 bottles. Data in both cases were logged using EG&G software running under MS-DOS and IBM type personal computers.

Calibration and Data Quality

In order to calibrate the different sensors of the two CTD systems used through the cruise, water samples and temperature readings were routinely taken during most of the CTD casts.


To achieve the calibration of the conductivity sensors, the water samples were analysed on the salinometer brought aboard as part of the equipment of the Spanish Institute of Oceanography (IEO), and the difference between the two sources of data (i.e. the data measured by the CTD minus the data from the salinometer) was calculated.


Similarly, in order to calibrate the temperature sensors the difference between the CTD and revering thermometers was also estimated.

The calibration curves of both parameters were then updated.

Following application of the calibration, each profile of temperature and salinity was iteratively displayed and corrected if necessary. As a first error inspection, artificial structures (i.e. isolated spikes) were removed and linear interpolation used to correct the profiles.


The Sea-Tech 57S fluorometer is a linear response instrument. The Chelsea Instruments Mark II Aquatracka is a logarithmic response instrument. Data derived from this instrument were comparatively noisy and were smoothed with a 7 point running average filter to remove the larger spikes and oscillations. Samples for fluorometer calibration were taken at known depths within several CTD and fluorescence profiles, using the Rosette bottles. Typical sampling depths include deep water, the chlorophyll-a maximum and the surface mixed layer. The bottle samples were analysed using a Turner bench fluorometer and the concentration of chlorophyll-a and phaeopigments calculated.

Sample concentrations of chlorophyll-a were plotted against their fluorescence voltage, measured on the corresponding profiling fluorometer. A linear regression analysis was performed on the Sea-Tech instrument data, whilst a non-linear curve fitting program was employed to establish the Chelsea Instruments Aquatracka calibration. These relationships were then used to convert all the fluorescence profiles to profiles of pigment concentration.

The following equations were used to convert the fluorometer voltages to predicted chlorophyll-a concentrations in mg/m3:

Sea-Tech fluorometer

fluorescence voltage = (3.67 x chlorophyll concentration) + 0.24

Chelsea Instruments Aquatracka fluorometer

fluorescence voltage = 2log ((2.90 x chlorophyll concentration) + 1) + 0.66


Velez-Munoz, H.S. October 1992.
Ignat Pavlyuchenkov Cruise Report: Hydrographic Field. European Coastal Transition Zone Islas Canarias, MAST Project 0031. Report 0031-09

Wild, K.A. May 1992.
Ignat Pavlyuchenkov Cruise Report: General and Phytoplankton Biomass. European Coastal Transition Zone Islas Canarias, MAST Project 0031. Report 0031-08

Project Information

European Coastal Transition Zone (ECTZ)

The European Coastal Transition Zone, Islas Canarias, (EU MAST Project 0031) was undertaken to improve understanding of physical and biological phenomena in the region of the Canary Islands, which are located at the transition zone between the eutrophic upwelling waters of the African continental shelf and the oligotrophic oceanic waters of the Canary Current.

Data Activity or Cruise Information


Cruise Name IP 9/91
Departure Date 1991-10-17
Arrival Date 1991-11-05
Principal Scientist(s)
Ship Ignat Pavlyuchenkov

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