Metadata Report for BODC Series Reference Number 789318


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Sea-Bird SBE 13 Dissolved Oxygen Sensor  dissolved gas sensors
Chelsea Technologies Group Aquatracka fluorometer  fluorometers
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
Chelsea Technologies Group Alphatracka transmissometer  transmissometers
Sea-Bird SBE 18 pH Sensor  pH sensors
Biospherical QSR-240 surface PAR  radiometers
Instrument Mounting lowered unmanned submersible
Originating Country Netherlands
Originator Dr Jo Suijlen
Originating Organization Rijkswaterstaat
Processing Status banked
Project(s) Provess
 

Data Identifiers

Originator's Identifier CTD120
BODC Series Reference 789318
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 1999-04-27 03:57
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 0.101 decibars
 

Spatial Co-ordinates

Latitude 52.43550 N ( 52° 26.1' N )
Longitude 4.06733 E ( 4° 4.0' E )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor Depth 2.2 m
Maximum Sensor Depth 20.8 m
Minimum Sensor Height 3.2 m
Maximum Sensor Height 21.8 m
Sea Floor Depth 24.0 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
ATTNMR01 1 per metre Atten_red Attenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
ATTNSR01 1 per metre ShortRed Attenuation (red light wavelength) per unit length of the water body by 5 or 10cm path length transmissometer
CPHLPR01 1 Milligrams per cubic metre chl-a_water_ISfluor Concentration of chlorophyll-a {chl-a CAS 479-61-8} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer
DOXYPR01 1 Micromoles per litre WC_dissO2_Beck Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ Beckmann probe
IRRDSV01 1 MicroEinsteins per square metre per second SurfVPAR Downwelling vector irradiance as photons (PAR wavelengths) in the atmosphere by cosine-collector radiometer
OXYSBB01 1 Percent BKBeck Saturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase] by in-situ Beckmann probe and computation from concentration using Benson and Krause algorithm
PHXXPR01 1 pH units pH pH per unit volume of the water body by pH electrode
POTMCV01 1 Degrees Celsius WC_Potemp Potential temperature of the water body by computation using UNESCO 1983 algorithm
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
PSALST01 1 Dimensionless P_sal_CTD Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm
SIGTPR01 1 Kilograms per cubic metre SigTheta Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPST01 1 Degrees Celsius WC_temp_CTD Temperature of the water body by CTD or STD
TSEDTR01 1 Milligrams per litre TSPMTr Concentration of suspended particulate material {SPM} per unit volume of the water body [particulate >unknown phase] by in-situ optical attenuance measurement and calibration against sample data
 

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

Sea Bird Electronics SBE13 Dissolved Oxygen Sensor

The SBE 13 was designed as an auxiliary sensor for Sea Bird SBE 9plus, but can fitted in custom instrumentation applications. When used with the SBE 9 Underwater Unit, a flow-through plenum improves the data quality, as the pumping water over the sensor membrane reduces the errors caused by oxygen depletion during the periods of slow or intermittent flushing and also reduces exposure to biofouling.

The output voltage is proportional to membrane current (oxygen current) and to the sensor element's membrane temperature (oxygen temperature), which is used for internal temperature compensation.

Two versions of the SBE 13 are available: the SBE 13Y uses a YSI polarographic element with replaceable membranes to provide in situ measurements up to 2000 m depth and the SBE 13B uses a Beckman polarographic element to provide in situ measurements up to 10500 m depth, depending on the sensor casing. This sensor includes a replaceable sealed electrolyte membrane cartridge.

The SBE 13 instrument has been out of production since 2001 and has been superseded by the SBE 43.

Specifications

Measurement range 0 to 15 mL L -1
Accuracy 0.1 mL L -1
Time response

2 s at 25°C

5 s at 0°C

Depth range

2000 m (SBE 13Y- housing in anodized aluminum)

6800 m (SBE 13B- housing in anodized aluminum)

105000 m (SBE 13B- housing in titanium)

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

SeaBird SBE18 pH sensor

This model uses a pressure-balanced glass-electrode/Ag/AgCl reference pH probe to provide in situ measurements up to 1200 m depth. It is a modular sensor designed to be used in a profiling mode only.

Specifications

Measurement range 0 to 14 pH
Accuracy 0.1 pH
Time response 1 sec
Depth rating 1200 m

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

Sea-Bird Electronics SBE 911 and SBE 917 series CTD profilers

The SBE 911 and SBE 917 series of conductivity-temperature-depth (CTD) units are used to collect hydrographic profiles, including temperature, conductivity and pressure as standard. Each profiler consists of an underwater unit and deck unit or SEARAM. Auxiliary sensors, such as fluorometers, dissolved oxygen sensors and transmissometers, and carousel water samplers are commonly added to the underwater unit.

Underwater unit

The CTD underwater unit (SBE 9 or SBE 9 plus ) comprises a protective cage (usually with a carousel water sampler), including a main pressure housing containing power supplies, acquisition electronics, telemetry circuitry, and a suite of modular sensors. The original SBE 9 incorporated Sea-Bird's standard modular SBE 3 temperature sensor and SBE 4 conductivity sensor, and a Paroscientific Digiquartz pressure sensor. The conductivity cell was connected to a pump-fed plastic tubing circuit that could include auxiliary sensors. Each SBE 9 unit was custom built to individual specification. The SBE 9 was replaced in 1997 by an off-the-shelf version, termed the SBE 9 plus , that incorporated the SBE 3 plus (or SBE 3P) temperature sensor, SBE 4C conductivity sensor and a Paroscientific Digiquartz pressure sensor. Sensors could be connected to a pump-fed plastic tubing circuit or stand-alone.

Temperature, conductivity and pressure sensors

The conductivity, temperature, and pressure sensors supplied with Sea-Bird CTD systems have outputs in the form of variable frequencies, which are measured using high-speed parallel counters. The resulting count totals are converted to numeric representations of the original frequencies, which bear a direct relationship to temperature, conductivity or pressure. Sampling frequencies for these sensors are typically set at 24 Hz.

The temperature sensing element is a glass-coated thermistor bead, pressure-protected inside a stainless steel tube, while the conductivity sensing element is a cylindrical, flow-through, borosilicate glass cell with three internal platinum electrodes. Thermistor resistance or conductivity cell resistance, respectively, is the controlling element in an optimized Wien Bridge oscillator circuit, which produces a frequency output that can be converted to a temperature or conductivity reading. These sensors are available with depth ratings of 6800 m (aluminium housing) or 10500 m (titanium housing). The Paroscientific Digiquartz pressure sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

Additional sensors

Optional sensors for dissolved oxygen, pH, light transmission, fluorescence and others do not require the very high levels of resolution needed in the primary CTD channels, nor do these sensors generally offer variable frequency outputs. Accordingly, signals from the auxiliary sensors are acquired using a conventional voltage-input multiplexed A/D converter (optional). Some Sea-Bird CTDs use a strain gauge pressure sensor (Senso-Metrics) in which case their pressure output data is in the same form as that from the auxiliary sensors as described above.

Deck unit or SEARAM

Each underwater unit is connected to a power supply and data logging system: the SBE 11 (or SBE 11 plus ) deck unit allows real-time interfacing between the deck and the underwater unit via a conductive wire, while the submersible SBE 17 (or SBE 17 plus ) SEARAM plugs directly into the underwater unit and data are downloaded on recovery of the CTD. The combination of SBE 9 and SBE 17 or SBE 11 are termed SBE 917 or SBE 911, respectively, while the combinations of SBE 9 plus and SBE 17 plus or SBE 11 plus are termed SBE 917 plus or SBE 911 plus .

Specifications

Specifications for the SBE 9 plus underwater unit are listed below:

Parameter Range Initial accuracy Resolution at 24 Hz Response time
Temperature -5 to 35°C 0.001°C 0.0002°C 0.065 sec
Conductivity 0 to 7 S m -1 0.0003 S m -1 0.00004 S m -1 0.065 sec (pumped)
Pressure 0 to full scale (1400, 2000, 4200, 6800 or 10500 m) 0.015% of full scale 0.001% of full scale 0.015 sec

Further details can be found in the manufacturer's 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 .

Biospherical Instruments Quantum Scalar Reference Sensor QSR-240

The QSR-240 is a hemispherical reference sensor designed to measure surface radiation. It has a scalar directional response and includes a field-of-view cutoff plate that transforms its response to a hemispherical one. An aluminium-encased optical light pipe funnels flux, from the collector to a silicon photodetector, that has a flat response over the Photosynthetically Active Radiation (PAR) spectrum (400 - 700 nm).

This instrument works as a transducer, providing and analog voltage output that is directly proportional to the incident irradiance upon the collectors' sensing plate. It is designed for surface measurements of total incident PAR from the sun and sky.

Specifications

Wavelength 400 to 700 nm
PAR Spectral Response better than ± 10% within the specified wavelength
PAR Dynamic Range 1.4 x 10 -5 to 0.5 µE cm -2 s -1
Nominal sensitivity 1 V = 1 x 10 17 quanta cm -2 sec -1
Noise level < 1 mV
Response Temperature Coefficient < 0.15% °C -1
Temperature Range -2 to 35°C
Temperature coefficient of the dark signal < 10 µV °C -1
Directional response

± 6% for 0 to 85°

0 at 95°

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

Chelsea Technologies Group ALPHAtracka and ALPHAtracka II transmissometers

The Chelsea Technologies Group ALPHA tracka (the Mark I) and its successor, the ALPHA tracka II (the Mark II), are both accurate (< 0.3 % fullscale) transmissometers that measure the beam attenuation coefficient at 660 nm. Green (565 nm), yellow (590 nm) and blue (470 nm) wavelength variants are available on special order.

The instrument consists of a Transmitter/Reference Assembly and a Detector Assembly aligned and spaced apart by an open support frame. The housing and frame are both manufactured in titanium and are pressure rated to 6000 m depth.

The Transmitter/Reference housing is sealed by an end cap. Inside the housing an LED light source emits a collimated beam through a sealed window. The Detector housing is also sealed by an end cap. A signal photodiode is placed behind a sealed window to receive the collimated beam from the Transmitter.

The primary difference between the ALPHA tracka and ALPHA tracka II is that the Alphatracka II is implemented with surface-mount technology; this has enabled a much smaller diameter pressure housing to be used while retaining exactly the same optical train as in the Mark I. Data from the Mark II version are thus fully compatible with that already obtained with the Mark I. The performance of the Mark II is further enhanced by two electronic developments from Chelsea Technologies Group - firstly, all items are locked in a signal nulling loop of near infinite gain and, secondly, the signal output linearity is inherently defined by digital circuitry only.

Among other advantages noted above, these features ensure that the optical intensity of the Mark II, indicated by the output voltage, is accurately represented by a straight line interpolation between a reading near full-scale under known conditions and a zero reading when blanked off.

For optimum measurements in a wide range of environmental conditions, the Mark I and Mark II are available in 5 cm, 10 cm and 25 cm path length versions. Output is default factory set to 2.5 volts but can be adjusted to 5 volts on request.

Further details about the Mark II instrument are available from the Chelsea Technologies Group ALPHA tracka II specification sheet .

MV Mitra 0499 CTD Data Documentation

Data Originator

Dr. Jo Suijlen, Rijkswaterstaat/Rijksinstituut voor Kurst en Zee (RWS/RIKZ), Den Haag, Netherlands.

Cruise Principal Scientist

Martyn Harvey, Dunstaffnage Marine Laboratory (DML), Oban, UK.

Content of data series

Parameter Unit Parameter code Number of stations Comments
Pressure db PRESPR01 167 none
Salinity PSU-78 PSALST01 167 none
Temperature deg. C TEMPST01 167 none
Potential temperature (UNESCO) deg. C POTMCV01 167 none
Sigma-theta (UNESCO SVAN) kg m -3 SIGTPR01 167 none
Chlorophyll a µg l -1 CPHLPR01 167 calibrated from fluorometer
Optical attenuance (10 cm transmissometer) m -1 ATTNSR01 167 see text
Optical attenuance (25 cm transmissometer) m -1 ATTNMR01 167 see text
Total suspended sediment mg l -1 TSEDTR01 167 calibrated from attenuance
Dissolved oxygen µmol l -1 DOXYPR01 167 none
Oxygen saturation percent OXYSBB01 167 none
pH pH units PHXXPR01 166 none
Downwelling PAR µE m -2 s -1 IRRDUV01 79 none
Surface PAR µE m -2 s -1 IRRDSV01 157 none

Instrumentation and data processing by originator

CTD unit and auxiliary sensors

Sea-Bird Electronics (SBE) 911 Plus system fitted with the following sensors:

SBE13 oxygen sensor with YSI 5739 oxygen probe
SBE18 pH sensor
Chelsea Instruments transmissometers with pathlength of 10 cm and 25 cm
Aquatracka fluorometer
underwater PAR sensor (Biospherical QSP-200L)
on-deck reference PAR sensor (Biospherical QSR-240)

The manufacturer's specifications are listed in the table below. All sensors were calibrated and checked once a year by the manufacturer.

Parameter Range Precision
pressure 0 to 1369 db ± 0.02 %
temperature -5°C to +35°C ± 0.01 °C
conductivity 0.0 to 7.0 S/m ± 0.001 S/m
pH 0 to 14 ± 0.1
oxygen 0 to 20 mg/l ± 0.03 mg/l
ox. temperature -5°C to +45°C ± 0.1 °C
light attenuation 400 to 700 nm 0.02% fs
turbidity 660 nm 0.01% fs
fluorescence 0.01 to 100 µg/l ± 0.01 µg/l

The precisions guaranteed by the North Sea Directorate were as follows:

better than 0.05 m for the pressure sensor
± 0.01 °C for temperature
± 0.005 S/m for conductivity
± 0.1 for pH

For the oxygen probe, dissolved oxygen concentrations measured by the probe were checked against oxygen concentration measured on surface water samples by the Winkler titration during the cruise. Calibration checks were performed on 19/04, 21/04, 26/04 and 29/04. The precision of the oxygen probe was acceptable within ± 6 % of the concentration measured by Winkler titration. On 21/04 a decrease in precision was noted and the oxygen sensor was replaced after cast 037.

Data were logged on a PC running Seabird data acquisition software version Seasave Win32 v.1.10 and manufacturer's calibration coefficients were applied to the raw data.

CTD data were supplied to BODC as downcasts only, binned to 0.1 m.

Sampling device

BODC post-cruise processing and screening

Reformatting

The data were converted into BODC internal format (PXF) to allow use of in-house software tools notably the workstation graphics editor SERPLO. In addition to reformatting, the transfer program applied the following modifications to the data:

attenuance (m -1 ) = -1/PL * log e (% transmission/100)

where PL is the transmissometer pathlength in metres (0.10 and 0.25 m).

Screening of data and metadata

Originator ID Parameter Cruise report CTD file header Value used in Provess Database
CTD018 Longitude 4 deg 47.75' 4 deg 17.75' 4 deg 17.75'
CTD042 Longitude 4 deg 6.68' 4 deg 9.68' 4 deg 9.68'
CTD055 Latitude 52 deg 17.19' 52 deg 27.19' 52 deg 27.19'
CTD067 Longitude 4 deg 28.28' 4 deg 18.28' 4 deg 18.28'
CTD079 Latitude 52 deg 15.56' 52 deg 18.56' 52 deg 18.56'

Banking

Once screened on the workstation, the CTD downcasts were loaded into a database under the ORACLE Relational Database Management System.

Calibration

Chl = 1.21 (±0.11) x CTD_FL + 1.72 (0.95), R 2 =0.730, n=49
TSED (mg l -1 ) = (ATTN - 0.2805) / 0.758, R 2 = 0.609, n=47

Comments on data quality

Reference

Zindler JS, Baretta JW, Heins C, Hoogervorst RDN, Suijlen JM (2001) Non-turbulent dynamics and water column biology and physics. Report RIKZ/OS/2001.112X


Project Information

PROcesses of Vertical Exchange in Shelf Seas (PROVESS)

Introduction

PROVESS was an interdisciplinary study of the vertical fluxes of properties through the water column and the surface and bottom boundary layers. The project was funded by the European Community MAST-III programme (MAS3-CT97- 0159) and ran from March 1998 to May 2001.

Scientific Rationale

PROVESS was based on the integration of experimental, theoretical and modelling studies with the aim of improving understanding and quantification of vertical exchange processes in the water column, in particular in the surface and benthic boundary layers and across the> pycnocline. PROVESS also explored mechanisms of physical-biological coupling in which vertical exchanges and turbulence significantly affect the environmental conditions experienced by the biota with particular reference to aggregation, flocculation, sedimentation and trophic interactions.

Fieldwork

The experimental phase of the project was carried out at two contrasting sites in the North Sea: the northern North Sea site (NNS) and the southern North Sea site (SNS).

The two sites had the following characteristics:

SNS NNS
Position 52° 15.0' N, 4° 17.0' E 59° 20.0' E, 1° 00.0' E
Time of year April-May September-November
Water depth (m) 16 100
M2 max amplitude (m s-1) 0.75 0.15
Max current (m s-1) 1.0 0.6
Delta T (deg C) mixed 7-1
Thermocline depth (m) mixed 35-100
Delta S 1 small
Halocline depth (m) 5-10 cf. thermocline depth
Max wind speed (m s-1) 20 25
Max wave height (m) 5 10
Max wave period (s) 8 10
Internal motion No Yes
Sediment muddy-sand muddy-sand
Biology eutrophic oligotrophic

At both locations measurements were concentrated at a central position with additional measurements being made to estimate horizontal gradients. Moored instruments (including current meters, temperature and pressure sensors, fluorometers, transmissometers, nutrient analysers and meteorological sensors) were deployed between 7 September and 5 November 1998 at the NNS and between 29 March and 25 May 1999 at the SNS. Each experiment was supported by intensive measurement series made from oceanographic ships and involving turbulence dissipation profiler CTD, particle size profilers, optical profilers, benthic sampling and water bottle sampling.

Details of the cruises were as follows:

Site Ship
(nationality)
Cruise
Mnemonic
Date
NNS Valdivia (GER) VA174 5 - 17 Sep 1998
  Dana (DK) D1198 14 - 26 Oct 1998
  Pelagia (NL) PE125 19 - 30 Oct 1998
  Challenger (UK) CH140 22 Oct - 9 Nov 1998
SNS Pelagia (NL) PE135 29 Mar - 9 Apr 1999
  Mitra (NL) MT0499 19 - 30 Apr 1999
  Belgica (BE) BG9912 17 - 21 May 1999

Data Activity or Cruise Information

Cruise

Cruise Name MT0499
Departure Date 1999-04-19
Arrival Date 1999-04-30
Principal Scientist(s)S Martyn Harvey (Scottish Association for Marine Science)
Ship RV Mitra

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