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Metadata Report for BODC Series Reference Number 1976314


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 ECO BB(RT)D Scattering Meter  optical backscatter sensors
Benthos PSA-916T Sonar Altimeter  altimeters
WETLabs C-Star transmissometer  transmissometers
Sea-Bird SBE 3plus (SBE 3P) temperature sensor  water temperature sensor
Sea-Bird SBE 4C conductivity sensor  salinity sensor
Chelsea Technologies Group Aquatracka III fluorometer  fluorometers
Paroscientific Digiquartz depth sensors  water pressure sensors
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Dr Penny Holliday
Originating Organization National Oceanography Centre, Southampton
Processing Status QC in progress
Online delivery of data Download not available
Project(s) UK-OSNAP
 

Data Identifiers

Originator's Identifier CTD_DY078_056_2DB
BODC Series Reference 1976314
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2017-05-21 20:01
End Time (yyyy-mm-dd hh:mm) 2017-05-21 20:36
Nominal Cycle Interval 2.0 decibars
 

Spatial Co-ordinates

Latitude 57.80900 N ( 57° 48.5' N )
Longitude 19.89280 W ( 19° 53.6' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 2.97 m
Maximum Sensor or Sampling Depth 1359.76 m
Minimum Sensor or Sampling Height 11.04 m
Maximum Sensor or Sampling Height 1367.84 m
Sea Floor Depth 1370.81 m
Sea Floor Depth Source DATAHEAD
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

No Parameters for BODC Reference Number = 1976314

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

DY078 CTD Data Quality Report

Screening and Quality Control

During BODC quality control, data were screened using in house visualisation software. The data were screened and any obvious outliers and spikes were looked at in closer detail and flagged if necessary.

DOXYSC01, OXYSZZ01

Problems with the autotritrator during DY078 meant the originator was unable to satisfactorily calibrate the oxygen data. There is a clear offset between this years calibrated oxygen values and previous years data in the deep waters where oxygen concentrations are expected to be fairly constant - the originator concluded that the DY078 calibration is suspect, therefore all calibrated data values (DOXYSC01) and values derived from them (OXYSZZ01) have been flagged 'L'.

AHSFZZ01

This channel has been flagged where values are constant or increase with depth. The altimeter only collects good data within 100 m of the seabed and these instances of constant values or increases with depth occur more than 100 m from the seabed.


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

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.

Benthos Programmable Sonar Altimeter (PSA) 916 and 916T

The PSA 916 is a submersible altimeter that uses the travel time of an acoustic signal to determine the distance of the instrument from a target surface. It provides the user with high resolution altitude or range data while simultaneously outputting data through a digital serial port. A wide beam angle provides for reliable and accurate range measurements under the most severe operational conditions. The instrument is electronically isolated to eliminate any potential signal interference with host instrument sensors. The PSA 916 is an upgrade of the PSA 900.

The standard model (PSA 916) has an operational depth range of 0 - 6000 m, while the titanium PSA 916T has a depth range of 0 - 10000 m. All other specifications for the two versions are the same.

Specifications

Transmit frequency 200 kHz
Transmit pulse width 250 µs
Beam pattern 14° conical
Pulse repetition rate

internal selection: 5 pps

external selection: up to 5 pps- user controlled

Range

100 m full scale

1.0 m guaranteed minimum

0.8 m typical

Range

1 cm for RS232 output

2.5 cm for analog output

Operating depth 6000 m (PSA 916) or 10000 m (PSA 916T)

Further details can be found in the manufacturer's specification sheets for the PSA 916 and the PSA 916T.

DY078 CTD Instrument Description

CTD Unit and Auxillary Sensors

A Sea-Bird 11plus CTD system used on cruise DY078. This was mounted on a 24-way stainless steel rosette frame, equipped with 24 10-litre Niskin bottles. The CTD was fitted with the following scientific sensors:

Sensor Serial Number Last calibration date Comments
Paroscientific Digiquartz depth sensors 110557 3 November 2016 -
Primary Temperature SBE-3P 2674 12 April 2016 -
Secondary Temperature SBE-3P 4383 17 February 2016 -
Primary Conductivity SBE-4C 2571 17 September 2015 -
Secondary Conductivity SBE-4C 2580 18 February 2016 -
Benthos PSA-916T Sonar Altimeter 59494 - -
Sea-Bird SBE 43 dissolved oxygen sensor 2818 28 July 2026 -
Sea-Bird SBE 43 dissolved oxygen sensor 2575 30 August 2016 -
Chelsea Aquatracka MKIII fluorometer 88-2615-126 22 July 2016 -
WETLabs C-Star transmissometer 1602TR 24 May 2016 -
WETLabs ECO BB(RT)D Scattering Meter 169 08 September 2016 -

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.

Chelsea Technologies Group Aquatracka MKIII fluorometer

The Chelsea Technologies Group Aquatracka MKIII is a logarithmic response fluorometer. Filters are available to enable the instrument to measure chlorophyll, rhodamine, fluorescein and turbidity.

It uses a pulsed (5.5 Hz) xenon light source discharging along two signal paths to eliminate variations in the flashlamp intensity. The reference path measures the intensity of the light source whilst the signal path measures the intensity of the light emitted from the specimen under test. The reference signal and the emitted light signals are then applied to a ratiometric circuit. In this circuit, the ratio of returned signal to reference signal is computed and scaled logarithmically to achieve a wide dynamic range. The logarithmic conversion accuracy is maintained at better than one percent of the reading over the full output range of the instrument.

Two variants of the instrument are available, both manufactured in titanium, capable of operating in depths from shallow water down to 2000 m and 6000 m respectively. The optical characteristics of the instrument in its different detection modes are visible below:

Excitation Chlorophyll a Rhodamine Fluorescein Turbidity
Wavelength (nm) 430 500 485 440*
Bandwidth (nm) 105 70 22 80*
Emission Chlorophyll a Rhodamine Fluorescein Turbidity
Wavelength (nm) 685 590 530 440*
Bandwidth (nm) 30 45 30 80*

* The wavelengths for the turbidity filters are customer selectable but must be in the range 400 to 700 nm. The same wavelength is used in the excitation path and the emission path.

The instrument measures chlorophyll a, rhodamine and fluorescein with a concentration range of 0.01 µg l-1 to 100 µg l-1. The concentration range for turbidity is 0.01 to 100 FTU (other wavelengths are available on request).

The instrument accuracy is ± 0.02 µg l-1 (or ± 3% of the reading, whichever is greater) for chlorophyll a, rhodamine and fluorescein. The accuracy for turbidity, over a 0 - 10 FTU range, is ± 0.02 FTU (or ± 3% of the reading, whichever is greater).

Further details are available from the Aquatracka MKIII specification sheet.

WETLabs Single-angle Backscattering Meter ECO BB

An optical scattering sensor that measures scattering at 117°. This angle was determined as a minimum convergence point for variations in the volume scattering function induced by suspended materials and water. The measured signal is less determined by the type and size of the materials in the water and is more directly correlated to their concentration.

Several versions are available, with minor differences in their specifications:

  • ECO BB(RT)provides analog or RS-232 serial output with 4000 count range
  • ECO BB(RT)D adds the possibility of being deployed in depths up to 6000 m while keeping the capabilities of ECO BB(RT)
  • ECO BB provides the capabilities of ECO BB(RT) with periodic sampling
  • ECO BBB is similar to ECO BB but with internal batteries for autonomous operation
  • ECO BBS is similar to ECO BB but with an integrated anti-fouling bio-wiper
  • ECO BBSB has the capabilities of ECO BBS but with internal batteries for autonomous operation

Specifications

Wavelength 471, 532, 660 nm
Sensitivity (m-1 sr-1)

1.2 x 10-5 at 470 nm

7.7 x 10-6 at 532 nm

3.8 x 10-6 at 660 nm

Typical range ~0.0024 to 5 m-1
Linearity 99% R2
Sample rate up to 8Hz
Temperature range 0 to 30°C
Depth rating

600 m (standard)

6000 m (deep)

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.

DY078 CTD data originator's processing

Sampling strategy

A total of 81 CTD casts were performed during the cruise.

Data processing

Data collection and basic processing of the raw data was completed in Sea-bird Seasave v7.26.2.13 software.

The data were then processed using the mexec_v2 software suite developed by NOC. The following modules were run:

  • DatCnv: converts raw frequency and voltage data by applying manufacturer's calibrations stored in the .XMLCON file, and outputs the data in an ASCII format (cast data as .cnv, bottle data as .ros).
  • Align: Shifts selected sensors' data in time, relative to pressure. This is required for sensors with a slower response time and when extra time is required for the water parcel to reach the sensor (e.g. traveling through extra lengths of hose). On this occasion only the oxygen SBE43 sensors required this step - a standard alignment of 6 seconds was applied to both. The primary and secondary conductivity channels also required a small shift of 0.073 seconds but this was done in real-time by the CTD deck-unit.
  • CellTM: This module removes conductivity cell thermal mass effects from the measured conductivity. Sea-bird recommended constants (α=0.03 and 1/β=7) were used.

Further details of the processing performed can be found in the cruise report.

DY078 CTD data processing by BODC

The CTD data were supplied to BODC as 81 MStar files and converted to the BODC internal format (netCDF).

During transfer the originator's variables were mapped to unique BODC parameter codes. The following table shows the parameter mapping.:

Originator's variable Units BODC Code Units Comments
press decibars PRESPR01 decibars -
temp degC TEMPST01 degC -
temp1 degC - - Secondary channel, not retained
temp2 degC - - Secondary channel, not retained
cond mS cm-1 CNDCST01 S m-1 Unit converion applied (divided by 10)
cond1 mS cm-1 - - Secondary channel, not retained
cond2 mS cm-1 - - Secondary channel, not retained
altimeter m AHSFZZ01 m -
oxygen1 µmol kg-1 DOXYSC01 µmol l-1 Conversion by BODC to µmol l-1 using TOKGPR01
oxygen2 µmol kg-1 DOXYSC02 µmol l-1 Conversion by BODC to µmol l-1 using TOKGPR01
fluor µg l-1 CPHLPR01 mg m-3 µg l-1=mg m-3
transmittance % POPTZZ01 % -
turbidity m-1 sr-1 BB117R01 m-1 nm-1 sr-1 m-1 sr-1 equivilent to m-1 nm-1 sr-1
psal pss-78 PSALST01 - Calculated from calibrated conductivity measurements, by the originator
psal1 pss-78 - - Secondary channel, not retained
psal2 pss-78 - - Secondary channel, not retained
depth m DEPHPR01 m -
potemp °C - - Not transferred - re-calculated by BODC from pressure, salinity and temperature
potemp1 °C - - Not transferred
potemp2 °C - - Not transferred
- - OXYSZZ01 % Derived by BODC using DOXYSC01, TEMPST01 and PSALST01
- - POTMCV01 °C Derived by BODC using TEMPST01, PSALST01 and PRESPR01.
- - SIGTPR01 kg m-3 Derived by BODC using POTMCV01, PSALST01 and PRESPR01
- - TOKGPR01 l kg-1 Derived by BODC using SIGTPR01

Following transfer the data were screened using BODC in-house visualisation software. Suspect data values were assigned the appropriate BODC data quality flag. Missing data values, where present, were changed to the missing data value and assigned a BODC data quality flag


Project Information

UK - Overturning in the Subpolar North Atlantic Programme (UK-OSNAP) Programme

UK-OSNAP is part of an international collaboration to establish a transoceanic observing system in the subpolar North Atlantic. The aim is to quantify and understand the Subpolar Gyre's response to local and remote forcing of mass, heat and freshwater fluxes, within the conceptual framework of the Atlantic Meridional Overturning Circulation (AMOC).

UK-OSNAP is developing a new observing system to provide a four year (2014 ? 2018) continuous record of full-depth, trans-basin mass, heat, and freshwater fluxes. Combining these sustained measurements with innovative modelling techniques will enable the project to characterise the circulation and fluxes of the North Atlantic Subpolar Gyre.

UK-OSNAP is funded by the Natural Environment Research Council (NERC). The project is led by the National Oceanography Centre (NOC) with partners in the University of Liverpool, the University of Oxford and the Scottish Association for Marine Science (SAMS). It is a part of international OSNAP that is led by USA and includes 10 further partner groups in Canada, France, Germany, the Netherlands and China. The project runs for five years from October 2013 and involves fieldwork at sea and model studies.

The OSNAP observing system consists of two legs: one extending from southern Labrador to the southwestern tip of Greenland across the mouth of the Labrador Sea (OSNAP West), and the second from the southeastern tip of Greenland to Scotland (OSNAP East). The observing system also includes subsurface floats (OSNAP Floats) in order to trace the pathways of overflow waters in the basin and to assess the connectivity of currents crossing the OSNAP line.

NERC have added a 2-year extension to UK-OSNAP, until October 2020. This will cover a 2-year deployment of 3 moorings in the Iceland Basin as part of the international OSNAP programme. The moorings will be recovered in 2020.


Data Activity or Cruise Information

Cruise

Cruise Name DY078 (DY079)
Departure Date 2017-05-06
Arrival Date 2017-05-28
Principal Scientist(s)N Penny Holliday (National Oceanography Centre, Southampton)
Ship RRS Discovery

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
Q value below limit of quantification