Metadata Report for BODC Series Reference Number 898102


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
SeaTech transmissometer  transmissometers
Sea-Bird SBE 43 Dissolved Oxygen Sensor  dissolved gas sensors
Sea-Bird SBE 25 Sealogger CTD  CTD; water temperature sensor; salinity sensor
Chelsea Technologies Group 2-pi PAR irradiance sensor  radiometers
SeaTech S131 fluorometer  fluorometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Ms Sarah Hughes
Originating Organization Fisheries Research Services Aberdeen Marine Laboratory (now Marine Scotland Aberdeen Marine Laboratory)
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier CU12/07/242
BODC Series Reference 898102
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2007-09-06 10:09
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 decibars
 

Spatial Co-ordinates

Latitude 60.35433 N ( 60° 21.3' N )
Longitude 1.50583 W ( 1° 30.3' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor Depth 0.99 m
Maximum Sensor Depth 97.05 m
Minimum Sensor Height 5.95 m
Maximum Sensor Height 102.01 m
Sea Floor Depth 103.0 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
ACYCAA01 1 Dimensionless Record_No Sequence number
ATTNMR01 1 per metre Atten_red Attenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
CNCLCCI1 1 Siemens per metre Cond_ind_cal Electrical conductivity of the water body by in-situ conductivity cell and calibration against independent measurements
CPHLPM01 1 Milligrams per cubic metre chl-a_water_ISfluor_manufctrcal_sensor1 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 and manufacturer's calibration applied
CPHLPS01 1 Milligrams per cubic metre chl-a_water_ISfluor_sampcal 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 and calibration against sample data
DOXYSU01 1 Micromoles per litre WC_dissO2_uncalib Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by Sea-Bird SBE 43 sensor and no calibration against sample data
IRRDUV01 1 MicroEinsteins per square metre per second SubsurVPAR Downwelling vector irradiance as photons (PAR wavelengths) in the water body by cosine-collector radiometer
IRRUUV01 1 MicroEinsteins per square metre per second EuPAR Upwelling vector irradiance as photons (PAR wavelengths) in the water body by cosine-collector radiometer
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
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

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 Dissolved Oxygen Sensor SBE 43 and SBE 43F

The SBE 43 is a dissolved oxygen sensor designed for marine applications. It incorporates a high-performance Clark polarographic membrane with a pump that continuously plumbs water through it, preventing algal growth and the development of anoxic conditions when the sensor is taking measurements.

Two configurations are available: SBE 43 produces a voltage output and can be incorporated with any Sea-Bird CTD that accepts input from a 0-5 volt auxiliary sensor, while the SBE 43F produces a frequency output and can be integrated with an SBE 52-MP (Moored Profiler CTD) or used for OEM applications. The specifications below are common to both.

Specifications

Housing Plastic or titanium
Membrane

0.5 mil- fast response, typical for profile applications

1 mil- slower response, typical for moored applications

Depth rating

600 m (plastic) or 7000 m (titanium)

10500 m titanium housing available on request

Measurement range 120% of surface saturation
Initial accuracy 2% of saturation
Typical stability 0.5% per 1000 h

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

Instrument Description

CTD Unit and Auxiliary Sensors

A Sea-Bird Electronics SBE 25 SEALOGGER CTD unit with an SBE 32 carousel water sampler was used. The CTD unit included the following sensors.

Sensor Manufacturer Model Serial number Calibration date
Pressure Sea-Bird SBE 29 0583 2006-06-14
Temperature Sea-Bird SBE 3F 4357 2005-11-17
Conductivity Sea-Bird SBE 4 2864 2005-11-17
Oxygen Sea-Bird SBE 43 0450 2005-05-03
Fluorometer Sea Tech Sea Tech Fluorometer 206 Unknown
Transmissometer Sea Tech Sea Tech Transmissometer 238D 1996-08-02
PAR Chelsea PAR Irradiance Meter 46071 2006-02-20
PAR Chelsea PAR Irradiance Meter 46072 2006-02-20

Sea-Bird SBE 25 SEALOGGER CTD

The SBE 25 SEALOGGER is a research-quality CTD profiling system used for coastal, estuarine and, can also be a practical option, for deep-water work. It is easily configured in the field for a wide range of auxiliary sensors. The SEALOGGER is self-powered, requires no conductive cable, and is designed for use up to 6800 meters (10,000 psia). It uses the SBE3F temperature and SBE4 conductivity sensors as well as having an external strain gauge pressure sensor. It provides pump-controlled T-C ducted flow, samples at 8 Hz, records internally and provides simultaneous real-time data via its built-in RS-232 interface.

The standard CTD unit comes with a plastic housing (rated to 600 m), although this can be replaced by aluminium housing for depths up to 6800 m.

Specifications

Parameter SBE 25
Temperature

Range: -5 to +35 °C

Accuracy: 0.002 °C

Resolution: 0.0003 °C

Conductivity

Range: 0 to 7 S m -1 (0 to 70 mmho cm -1 )

Accuracy: 0.0003 S m -1

Resolution: 0.00004 S m -1

Strain gauge pressure sensor

Range: 0 to 20, 100, 350, 600, 1000, 2000, 3500, 7000 metres (expressed in metres of deployment depth capability)

Accuracy: 0.1% of full scale range

Resolution: 0.015% of full scale range

Options and accessories

Additional sensors can be attached to the CTD, including:

The SBE 5T titanium pump can be used in place of SBE 5P pump. Further details can be found in the manufacturer's SBE 25 instrument specification.

SeaTech fluorometer S131

This fluorometer is designed to measure in situ chlorophyll- a fluorescence and provide high resolution data for assessment of phytoplankton biomass and monitoring of primary productivity in fresh or marine waters. It's versatility allows the instrument to be deployed on a mooring or in profiling mode. It is not sensitive to ambient light, permitting laboratory calibration with normal room lighting, and field measurements to be made at the water surface.

Specifications

Nominal Chl- a ranges 3, 10, 30, 100, 300 and 1000 µg L -1
Time constant 0.1, 1.0, 3.0 and 10 s
Maximum depth 3000 m
Excitation filter

425 nm peak

200 nm FWHM *

Emission filter

685 nm peak

30 nm FWHM

*FWHM- Full-Width Half-Maximum

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

Chelsea Technologies Photosynthetically Active Radiation (PAR) Irradiance Sensor

This sensor was originally designed to assist the study of marine photosynthesis. With the use of logarithmic amplication, the sensor covers a range of 6 orders of magnitude, which avoids setting up the sensor range for the expected signal level for different ambient conditions.

The sensor consists of a hollow PTFE 2-pi collector supported by a clear acetal dome diverting light to a filter and photodiode from which a cosine response is obtained. The sensor can be used in moorings, profiling or deployed in towed vehicles and can measure both upwelling and downwelling light.

Specifications

Operation depth 1000 m
Range 2000 to 0.002 µE m -2 s -1
Angular Detection Range ± 130° from normal incidence
Relative Spectral Sensitivity

flat to ± 3% from 450 to 700 nm

down 8% of 400 nm and 36% at 350 nm

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

SeaTech Transmissometer

Introduction

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.

Specifications

Notes

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 .

BODC Processing

Data were received by BODC in one ASCII format file that was subsequently split into 153 separate files, one for each CTD profile. The series were reformatted to the internal QXF format using BODC transfer function 340. Sample calibrations were applied to the conductivity and fluorescence data. The following table details the mapping of variables to BODC parameter codes.

Original parameter name Original Units Description BODC Parameter Code BODC Units Comments
Pressure Decibars Pressure exerted by the water column PRESPR01 Decibars  
Temperature °C Temperature of the water column TEMPST01 °C  
Conductivity mS cm -1 Electrical conductivity of the water column calibrated against independent measurements CNCLCCI1 S m -1 Conversion by transfer (mS cm -1 x 0.1). Sample calibrations applied by transfer
Salinity   Salinity of the water column PSALST01 Dimensionless Derived by transfer using UNESCO 1983 algorithm
Fluorescence µg l -1 In-situ fluorescence CPHLPM01 mg m -3  
Fluorescence µg l -1 In-situ fluorescence with field sample calibration applied CPHLPS01 mg m -3 Sample calibrations applied to raw fluorescence by transfer
Dissolved oxygen ml l -1 Dissolved oxygen with no field calibration against sample data DOXYSU01 µmol l -1 Conversion by transfer (ml l -1 x 44.6)
Beam attenuation m -1 Attenuance of the water column ATTNMR01 m -1  
Downwelling PAR Volts Downwelling vector irradiance in the water column IRRDUV01 µEinstein m -2 s -1 Derived from raw voltages by transfer using manufacturer's calibrations
Upwelling PAR Volts Upwelling vector irradiance in the water column IRRUUV01 µEinstein m -2 s -1 Derived from raw voltages by transfer using manufacturer's calibrations

Following transfer to QXF, the data were screened using BODC's in-house visualisation software, EDSERPLO. Any data considered as suspect were flagged 'M'. Flags from the originator marking suspect data were retained during transfer and flagged 'L'.

Originator's Data Processing

Sampling Strategy

A total of 153 CTD casts were performed on FRV Clupea cruise 1207C (27 August 2007 - 10 September 2007) around Shetland and the north west of Scotland, including the coast of the mainland and the Inner and Outer Hebrides. The CTDs were collected close to the coast in all cases, frequently within sea lochs. The data were collected between 07:00 and 19:00 hours during the period 28 August 2007 - 08 September 2007.

Rosette bottles were fired in order to obtain independent salinity and fluorescence measurements. The sample data were used to derive calibrations for the conductivity and fluorescence profiles collected by the CTD.

Data Processing

The raw CTD data files were processed through the SeaBird Electronics SeaSoft data processing software following standard procedures. The originators used in-house interactive visual display editing software to edit out individual spikes in the primary temperature and conductivity channels. In addition, a low-pass filter (Sy 1985) was applied to particularly noisy data. An ASCII file was generated for each CTD cast and all files from a cruise were concatenated into one ASCII file which was submitted to BODC.

Sy A., 1985. An alternative editing technique for oceanographic data. Deep Sea Research Part A: Oceanographic Research Papers, 32 (12), 1591-1599.

Field Calibrations

Independent salinity samples, obtained from the CTD rosette and spread throughout the cruise, were used to calibrate the CTD conductivity data. Outlying points were discarded, and between 48 and 72 data points were used to derive the calibrations. The sample analyses yielded a straight line conductivity calibration of the form y = mx + c, where m = 1.002568 and c = -0.092409.

Water samples obtained from the CTD rosette were also used to calibrate the CTD fluorescence data. The sample analyses yielded a straight line fluorescence calibration of the form y = mx + c, where m = 28.903 and c = -0.158257.

The uncalibrated data and calibrations were submitted to BODC, who applied the appropriate corrections.


Project Information


No Project Information held for the Series

Data Activity or Cruise Information

Cruise

Cruise Name 1207C
Departure Date 2007-08-27
Arrival Date 2007-09-10
Principal Scientist(s)Matt Gubbins (Fisheries Research Services Aberdeen Marine Laboratory)
Ship FRV Clupea

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