Metadata Report for BODC Series Reference Number 1038253


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Sea-Bird SBE 43 Dissolved Oxygen Sensor  dissolved gas sensors
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
WETLabs C-Star transmissometer  transmissometers
WETLabs ECO-FLNTU combined fluorometer and turbidity sensor  fluorometers; optical backscatter sensors
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Mr George Slesser
Originating Organization Marine Scotland Aberdeen Marine Laboratory
Processing Status banked
Project(s) -
 

Data Identifiers

Originator's Identifier SC16/09/769
BODC Series Reference 1038253
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2009-12-14 21:18
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 decibars
 

Spatial Co-ordinates

Latitude 58.05017 N ( 58° 3.0' N )
Longitude 1.24217 W ( 1° 14.5' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor Depth 1.98 m
Maximum Sensor Depth 97.07 m
Minimum Sensor Height 10.93 m
Maximum Sensor Height 106.02 m
Sea Floor Depth 108.0 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
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
OXYSZZ01 1 Percent O2Sat Saturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase]
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

FRV Scotia 1609S Data quality report

The attenuation channel contains a significant proportion of noisy data.

These data should be used with caution.


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 911plus CTD unit was used. Water samples were collected with a SBE 35 Carousel, which was attached to the CTD frame. The CTD unit included the following sensors.

Sensor Manufacturer Model Serial number Calibration date
Pressure Paroscientific   64240 2009-06-30
Temperature Sea-Bird   2041 2008-07-10
Conductivity Sea-Bird   1615 2008-07-23
Fluorometer WetLabs ECO_FL FLRTD-064 2003-11-08
Transmissometer WetLabs C-Star CST-704DR 2003-08-25
Oxygen Sea-Bird   0504 2009-06-23

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 .

WETLabs ECO FLNTU fluorescence and turbidity sensor

The Environmental Characterization Optics (ECO) Fluorometer and Turbidity (FLNTU) sensor is a dual wavelength, single-angle instrument that simultaneously determines chlorophyll fluorescence and turbidity. It is easily integrated in CTD packages and provides a reliable turbidity measurement that is not affected by Colored Dissolved Organic Matter (CDOM) concentration.

The FLNTU can operate continuously or periodically and has two different types of connectors to output the data. There are 5 other models that operate the same way as this instrument but have slight differences, as stated below:

Specifications

Temperature range 0 to 30°C
Depth rating

600 m (standard)

6000 m (deep)

Turbidity
Wavelength 700 nm
Sensitivity 0.01 NTU
Typical range 0.01 to 25 NTU
Fluorescence
Wavelength 470 nm (excitation), 695 nm (emission)
Sensitivity 0.01 µg L -1
Typical range 0.01 to 50 µg L -1
Linearity 99% R 2

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

WETLabs C-Star transmissometer

This instrument is designed to measure beam transmittance by submersion or with an optional flow tube for pumped applications. It can be used in profiles, moorings or as part of an underway system.

Two models are available, a 25 cm pathlength, which can be built in aluminum or co-polymer, and a 10 cm pathlength with a plastic housing. Both have an analog output, but a digital model is also available.

This instrument has been updated to provide a high resolution RS232 data output, while maintaining the same design and characteristics.

Specifications

Pathlength 10 or 25 cm
Wavelength 370, 470, 530 or 660 nm
Bandwidth

~ 20 nm for wavelengths of 470, 530 and 660 nm

~ 10 to 12 nm for a wavelength of 370 nm

Temperature error 0.02 % full scale °C -1
Temperature range 0 to 30°C
Rated depth

600 m (plastic housing)

6000 m (aluminum housing)

Further details are available in the manufacturer's specification sheet or user guide .

BODC Processing

Data were received by BODC in one ASCII format file that was subsequently split into 58 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 data. The following table details 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  
Attenuation Volts Transmissivity of the water column ATTNMR01 m -1  
Oxygen ml l -1 Oxygen concentration DOXYSU01 µMoles l -1 Conversion by transfer (ml l -1 x 44.66)
Oxygen Saturation % Percentage oxygen saturation of the water column OXYSZZ01 %  

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

Originator's Data Processing

Sampling Strategy

A total of 58 CTD casts were performed on FRV Scotia cruise 1609S (02 December 2009 - 16 December 2009) along the JONSIS, Fair-Isle Munken and Nolso Flugga lines. The data were collected between 16:26 hours on 02 November 2009 and 02:38 hours on 15 December 2009.

Water samples were collected in order to obtain independent salinity measurements. The sample data were used to derive calibrations for the conductivity 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 sample bottle and spread throughout the cruise, were used to calibrate the CTD conductivity data. Outlying points were discarded, and 115 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=1.000013 and c = 0.003041.

Parameter Value of m (y=mx+c) Value of c (y=mx+c) Equation
Conductivity 1.000013 0.003041 C(cal) = 1.000013C(obs) + 0.003041

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 1609S
Departure Date 2009-12-02
Arrival Date 2009-12-16
Principal Scientist(s)John Dunn (Marine Scotland Aberdeen Marine Laboratory)
Ship FRV Scotia

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