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Metadata Report for BODC Series Reference Number 1624320


Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
NameCategories
Sea-Bird SBE 911 CTD  CTD; water temperature sensor; salinity sensor
Sea-Bird SBE 43 Dissolved Oxygen Sensor  dissolved gas sensors
WET Labs {Sea-Bird WETLabs} ECO BB(RT)D backscattering sensor  optical backscatter sensors
Biospherical Instruments QCP-2300 underwater PAR sensor  radiometers
Paroscientific 410K Pressure Transducer  water temperature sensor; water pressure sensors
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
Chelsea Technologies Group Alphatracka II transmissometer  transmissometers
Instrument Mounting lowered unmanned submersible
Originating Country United Kingdom
Originator Dr Jo Hopkins
Originating Organization National Oceanography Centre, Liverpool
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Shelf Sea Biogeochemistry (SSB)
SSB CaNDyFloSS
 

Data Identifiers

Originator's Identifier DY021_CAST022_STNNBR_301
BODC Series Reference 1624320
 

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2015-03-17 11:01
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 1.0 decibars
 

Spatial Co-ordinates

Latitude 50.59268 N ( 50° 35.6' N )
Longitude 7.01283 W ( 7° 0.8' W )
Positional Uncertainty 0.0 to 0.01 n.miles
Minimum Sensor or Sampling Depth 3.97 m
Maximum Sensor or Sampling Depth 100.1 m
Minimum Sensor or Sampling Height 8.9 m
Maximum Sensor or Sampling Height 105.03 m
Sea Floor Depth 109.0 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

BODC CODERankUnitsTitle
ACYCAA011DimensionlessSequence number
ATTNMR011per metreAttenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
BB117R021per metre per nanometre per steradianAttenuation due to backscatter (650 nm wavelength at 117 degree incidence) by the water body [particulate >unknown phase] by in-situ optical backscatter measurement
CNDCST011Siemens per metreElectrical conductivity of the water body by CTD
CPHLPS011Milligrams 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 and calibration against sample data
DOXYZZ011Micromoles per litreConcentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ sensor
IRRDPP011MicroEinsteins per square metre per secondDownwelling 2-pi scalar irradiance as photons of electromagnetic radiation (PAR wavelengths) in the water body by 2-pi scalar radiometer
OXYSZZ011PercentSaturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase]
POTMCV011Degrees CelsiusPotential temperature of the water body by computation using UNESCO 1983 algorithm
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
SIGTPR011Kilograms per cubic metreSigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO 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

Open 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.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."


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 for DY021 stainless steel frame CTD

CTD Unit and Auxiliary Sensors

The CTD unit comprised a Sea-Bird Electronics (SBE) 9plus underwater unit, an SBE 11plus deck unit, a 24-way SBE 32 carousel and 24 10 L TMF Water Samplers; all of which were mounted on a stainless steel 24-way CTD frame. Attached to the CTD were two SBE 3P temperature sensors, two SBE 4C conductivity sensors, one Paroscientific Digiquartz pressure sensor, one SBE 43 dissolved oxygen sensor, two CTD 2-π Underwater PAR sensors, one WETLabs BBRTD light scattering sensor, one Benthos 916T altimeter one CTG Aquatracka MKIII fluorometer and one CTG Alphatracka MKII transmissometer.

Sensor unit Model Serial number Full specification Calibration dates (YYYY/MM/DD) Comments
CTD underwater unit SBE 9plus 09P-24680-0637 SBE 9plus - -
CTD deck unit SBE 11plus 11P-34173-0676 - - -
Carousel SBE 32 - 24 Position Pylon 32-31240-0423 SBE 32 - -
Pressure sensor Paroscientific Digiquartz 79501 Paroscientific Digiquartz 2015-01-06 -
Temperature sensor SBE 3P 3P-2674 SBE 03P 2013-07-02 -
Temperature sensor SBE 3P 3P-2919 - 2013-10-19 -
Conductivity senor SBE 4C 4C-2571 SBE 04C 2013-07-02 -
Conductivity sensor SBE 4C 4C-3258 - 2014-03-25 -
Dissolved oxygen sensor SBE 43 43-2575 SBE 43 2014-04-10 -
Altimeter Benthos PSA 916T 59493 Benthos Altimeter - -
Irradiance sensor (UWIRR) Biospherical QCP Cosine PAR 70510 Biospherical QCP PAR sensor 2015-01-06 Measuring downwelling irradiance
Irradiance sensor (DWIRR) Biospherical QCP Cosine PAR 70520 - 2015-01-06 Measuring downwelling irradiance
Light scattering sensor WETLabs BBRTD BBRTD-1055 WETLabs BBRTD 2013-03-13 -
Fluorometer Chelsea MKIII Aquatracka 88-2615-124 Chelsea MKII Aquatracka 2012-10-19 -
Transmissometer Chelsea MKII Alphatracka - 25 cm path 161048 Alphatracka MKII 2012-07-24 -

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.

Biospherical Instruments Log Quantum Cosine Irradiance Sensor QCP-2300 & QCP-2350

The QCP-2300 is a submersible cosine-collector radiometer designed to measure irradiance over Photosynthetically Active Radiation (PAR) wavelengths. It features a constant (better than ±10%) quantum response from 400 to 700 nm with the response being sharply attenuated above 700 nm and below 400 nm.

The sensor is a blue-enhanced high stability silicon photovoltaic detector with dielectric and absorbing glass filter assembly. The output is a DC voltage typically between 0 and 5 VDC that is proportional to the log of the incident irradiance.

The QCP-2300 is specifically designed for integration with 12-bit CTD systems and dataloggers requiring a limited-range of signal input.

Specifications

Wavelength 400 to 700 nm
PAR Spectral Response better than ± 10% over 400-700 nm
Cosine Directional Response ± 5% 0 to 65°; ± 10% 0 to 85°
Noise level < 1 mV
Temperature Range -2 to 35 °C
Depth Range (standard) 1000 m

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

.

Chelsea Technologies Group ALPHAtracka and ALPHAtracka II transmissometers

The Chelsea Technologies Group ALPHAtracka (the Mark I) and its successor, the ALPHAtracka 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 ALPHAtracka and ALPHAtracka 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 ALPHAtrackaII 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.

Paroscientific Absolute Pressure Transducers Series 3000 and 4000

Paroscientific Series 3000 and 4000 pressure transducers use a Digiquartz pressure sensor to provide high accuracy and precision data. The sensor comprises a quartz crystal resonator that responds to pressure-induced stress, and temperature is measured for thermal compensation of the calculated pressure.

The 3000 series of transducers includes one model, the 31K-101, whereas the 4000 series includes several models, listed in the table below. All transducers exhibit repeatability of better than ±0.01% full pressure scale, hysteresis of better than ±0.02% full scale and acceleration sensitivity of ±0.008% full scale /g (three axis average). Pressure resolution is better than 0.0001% and accuracy is typically 0.01% over a broad range of temperatures.

Differences between the models lie in their pressure and operating temperature ranges, as detailed below:

Model Max. pressure (psia) Max. pressure (MPa) Temperature range (°C)
31K-101 1000 6.9 -54 to 107
42K-101 2000 13.8 0 to 125
43K-101 3000 20.7 0 to 125
46K-101 6000 41.4 0 to 125
410K-101 10000 68.9 0 to 125
415K-101 15000 103 0 to 50
420K-101 20000 138 0 to 50
430K-101 30000 207 0 to 50
440K-101 40000 276 0 to 50

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

Originator's processing document for DY021 CTD data

Sampling strategy

A total of 30 stainless steel frame CTD casts and 8 titanium frame CTD casts were performed during DY021, which sailed from Southampton on 01 March 2015 and docked in Southampton on 26th March 2015. Six process stations - four on the shelf edge (Benthic A, Benthic G, Benthic H and Benthic I) and two shelf edge stations (Candyfloss and CS2) - were sampled during DY021 and further CTD casts were performed for mooring and glider calibration purposes.

Data Processing

For each CTD cast the following raw data files were generated:

  • DY021_XYZ.bl (a record of bottle firing locations)
  • DY021_XYZ.hdr (header file)
  • DY021_XYZ.hex (raw data file)
  • DY021_XYZ.con (configuration file)

where XYZ is the cast number of the CTD data series.

The following processing was performed by the Originator using the SBE Data Processing software (Seasave Version 7.23.2):

  1. DatCnv was used to read in the raw CTD data file (.hex) which contained the data in engineering units and apply calibrations as appropriate through the instrument configurations (.con) file.
  2. Bottle Summary was run to create a .btl file containing the average, standard deviation, min and max values recorded by the CTD instrument suite at bottle firings.
  3. Wild Edit was run to remove spikes in the pressure channel.
  4. Filter was run on the pressure channel to smooth out the high frequency data
  5. AlignCTD was run to advance the stainless steel CTD oxygen data by two seconds and the titanium frame CTD oxygen data by four seconds.
  6. CellTM was run using alpha = 0.03 and 1/beta = 7 (for both CTD packages), to correct for conductivity errors induced by the transfer of heat from the conductivity cell to the seawater.
  7. Derive was run to create the variables Salinity, Salinity 2, Oxygen SBE 43 and Oxygen Tau correction. The output file was then saved as DY021_XYZ_derive.cnv.
  8. BinAverage and Strip were run to average the data to 2Hz bins (0.5 seconds) and to remove the salinity and oxygen channels which were created when Derive was run. The output file was then saved as DY021_XYZ_derive_2Hz.cnv.

The originator then proceeded to process the data further in Matlab.

  1. The data from the 2HZ and 24HZ processed CTD data files were extracted and combined with metadata from the Event log to create .mat files for each series at both 2HZ and 24 HZ resolutions.
  2. Inspection of the raw turbidity data revealed that there was a bug in the Seasave DatCnv conversion module which resulted in it incorrectly converting the raw turbidity voltage into m-1 sr-1. Therefore, the originator re-derived turbidity manually using the following equation (SF = scale factor, DC = dark counts):

    CTDturb = CTDturb_raw x SF - (SF x DC)

  3. The originator manually inspected the 2Hz data files to identify the surface soak and then cropped the 2Hz and 24Hz data files to remove the surface soak from the data.
  4. The salinity, conductivity, temperature, oxygen, attenuation, turbidity and fluorescence channels in the 24Hz data files were all de-spiked using an automated routine, with the originator converting the spikes to NaN (not a number) values.
  5. Further manual de-spiking was carried out to identify larger periods of bad data.
  6. The 24Hz data were averaged into one decibar downcast only bins and liner interpolation was used to fill gaps in the profile.
  7. All channels except PAR were smoothed further using a 10 m running median.
  8. The salinity data were then calibrated using salinity samples collected by the CTD water bottles and analysed on a Guildline Autosal salinometer. The chlorophyll fluorescence and dissolved oxygen channels were calibrated against water bottle samples. A calibration could not be determined for titanium chlorophyll so this channel remains uncalibrated for the titanium frame CTD.
  9. It was this calibrated version of the data which were then ingested by BODC, although all other versions have been archived and are available on request.

Field Calibrations

Salinity

A total of 99 salinity samples were collected from the stainless steel CTD and 38 salinity samples were collected from the titanium frame CTD to be analysed on a Guildline Autosal salinometer. The originator observed a temporal drift in the Autosal-CTD values in both the primary and secondary conductivity sensors from both the stainless and titanium frame CTD. The size of the drift was approximately 0.005 PSU for the stainless steel frame CTD and 0.003 PSU for the titanium frame CTD. The magnitude of the drift cannot be accounted for instability in the Autosal readings, as the difference between the salinity standards run before and after each salinity crate was measured is an order of magnitude greater than the observed drift.

The trend was significant and appears to be a temporal drift associated with each conductivity sensor, as if it was autosal drift then the salinity values recorded would be more consistent within each crate of samples which was run through the salinometer. There were also significant trends observed between CTD temperature and salinity, however these were weaker and may have been introduced coincidentally by the spatial sampling pattern on the cruise. For more information on the salinity calibration performed for DY021 see the originator's processing report linked at the bottom of this document.

Stainless steel frame CTD

Due to the above issues, two regressions were applied to the salinity data from the stainless steel frame CTD. The first calibration corrected for the temporal drift observed in the data. Once this calibration had been applied, the originator performed a second correction to correct for the small temperature related drift observed, in order to better align the data from the two sensors.

Regression applied for temporal drift to stainless sensors:

CTDsal_cal1 = CTDsal + (intercept + (slope x daynumber))

Primary intercept = 0.007896260752417

Primary slope = -0.000116230843654996

Secondary intercept = 0.015087956132598

Secondary slope = 0.0001586872897987173

Regression applied for thermal drift to stainless sensors:

CTDsal_cal2 = CTDsal_cal1 + (intercept + (slope x temperature))

Primary intercept = 0.001308186425552

Primary slope = -0.0001360663649035130

Secondary intercept = -0.002849682684898

Secondary slope = 0.0002963393480742600

Titanium frame CTD

CTDsal_cal = CTDsal + (intercept + (slope x daynumber))

Primary intercept = 0.014492859793267

Primary slope = -0.0001668293686343925

Secondary intercept = 0.015985420500784

Secondary slope = -0.0001883672231497256

After the above calibration was performed the trends between temperature and salinity disappeared, so the originator did not perform the thermal drift correction on the salinity data from the titanium frame CTD.

Chlorophyll

Stainless steel frame CTD

59 chlorophyll samples were collected from the stainless steel frame CTD during cruise DY034. Once all chlorophyll samples collected from the top 30 m of water during daylight hours were removed, a total of 29 chlorophyll samples remained to calibrate the CTD fluorometer attached to the stainless steel frame CTD. The originator used a linear regression to calibrate the chlorophyll fluorometer against the 29 chlorophyll samples, with the following calibration equation being used to calibrate the fluorometer:

CHL = 2.1084 x CTDfluor - 0.00007546

R2 = 0.79931

Titanium frame CTD

Only 4 chlorophyll samples were taken from the titanium CTD (all of these from cast 31). This was not enough to perform a reliable calibration, therefore the titanium frame CTD chlorophyll channel remains uncalibrated

Oxygen

Stainless steel frame CTD

81 oxygen samples were collected from the stainless steel frame CTD to calibrate the dissolved oxygen sensor. The originator used a linear regression to calibrate the dissolved oxygen sensor against the 81 samples, with the following calibration equation being used to calibrate the dissolved oxygen sensor:

Oxygen = 1.0148 x CTDoxy + 8.5911

R2 = 0.9883

Titanium frame CTD

20 oxygen samples were collected from the titanium frame CTD to calibrate the dissolved oxygen sensor. The originator used a linear regression to calibrate the dissolved oxygen sensor against the 98 oxygen samples. Due to the small number of samples, the calibrated dissolved oxygen values recorded by the stainless steel frame CTD on consecutive casts were also used in the linear regression. The following calibration equation being used to calibrate the dissolved oxygen sensor:

Oxygen = 1.0038 x CTDoxy + 8.7088

R2 = 0.9441

More information on the processing carried out and calibrations applied by the data originator the can be found in the data originator's CTD Processing Report.

Processing by BODC of RRS Discovery DY021 stainless steel frame CTD data

Several versions of the CTD data recorded during DY021 arrived at BODC in the form of ASCII and Matlab (.MAT) files. In addition to the raw CTD data, BODC were provided with the 24 Hz and 2 Hz versions created at the end of the originator's Seasave processing and at each subsequent stage of Matlab processing. The fully calibrated CTD data binned to 1db downcast bins were then reformatted to BODC's internal NetCDF format, however all earlier versions of the data supplied to BODC have been archived and are available on request. The following table shows the mapping of the originator's variables to the appropriate BODC parameter codes:

Originator's Variable Units Description BODC Parameter Code Units Comment
pres db Pressure (spatial co-ordinate) exerted by the water body by profiling pressure sensor and corrected to read zero at sea level PRESPR01 Decibars -
time elapsed [seconds] - - - This variable was not transferred.
temp1 °C Temperature of the water body by CTD or STD TEMPST01 °C -
temp2 °C - - - This parameter was dropped following screening as there was no difference between the quality of the data from the first and second temperature sensors
cond1 S m-1 Electrical conductivity of the water body by CTD CNDCST01 S m-1 -
cond2 S m-1 - - - This parameter was dropped following screening as there was no difference between the quality of the data from the first and second temperature sensors
sal1 PSU Practical salinity of the water body by CTD and computation using UNESCO 1983 algorithm PSALST01 Dimensionless derived from temp1 and cond1
sal2 PSU - - - This parameter was dropped following screening as there was no difference between the quality of the data from the first and second temperature sensors
oxy_umoll µ mol l-1 Concentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ sensor DOXYZZ01 µ mol l-1 -
fluor µ g l-1 Concentration of chlorophyll-a {chl-a} per unit volume of the water body [particulate >unknown phase] by in-situ chlorophyll fluorometer and calibration against sample data CPHLPS01 mg m-3 µ g l-1 = mg m-3
par W m-2 Downwelling 2-pi scalar irradiance as energy (PAR wavelengths) in the water body by 2-pi scalar radiometer DWIRPP01 W m-2 This channel was deleted from the following casts by BODC during screening as all values in profile were 0: casts 001, 008, 010, 037
att m -1 Attenuance (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer ATTNMR01 m -1 -
sigma_theta - - - - This variable was not transferred. BODC independently derive density during transfer
turb m-1 sr-1 Attenuance due to backscatter (650 nm wavelength at 117 degree incidence) by the water body [particulate >unknown phase] by in-situ optical backscatter measurement BB117R02 m-1 nm -1 sr-1 m-1 sr-1 = m-1 nm -1 sr-1

The following additional parameters were derived when the data were converted into QXF format:

Originator's Variable Units Description BODC Parameter Code Units Comment
- - Potential temperature of the water body by computation using UNESCO 1983 algorithm POTMCV01 °C Derived from TEMPST01, PSALST01 and PRESPR01
- - Sigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm SIGTPR01 kg m-3 Derived from POTMCV01, PSALST01 and PRESPR01
- - Saturation of oxygen {O2} in the water body [dissolved plus reactive particulate phase] OXYSZZ01 % Derived from TEMPST01, PSALST01 and DOXYZZ01

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, and missing data by setting the data to an appropriate value and applying the quality control flag. The secondary data channels were dropped as there was no clear difference in the quality of the data from the primary and secondary channels.


Project Information

Shelf Sea Biogeochemistry (SSB) Programme

Shelf Sea Biogeochemistry (SSB) is a £10.5 million, six-year (2011-2017) research programme, jointly funded by the Natural Environment Research Council (NERC) and the Department for Environment, Food and Rural Affairs (DEFRA). The aim of the research is to reduce the uncertainty in our understanding of nutrient and carbon cycling within the shelf seas, and of their role in global biogeochemical cycles. SSB will also provide effective policy advice and make a significant contribution to the Living with Environmental Change programme.

Background

The Shelf Sea Biogeochemistry research programme directly relates to the delivery of the NERC Earth system science theme and aims to provide evidence that supports a number of marine policy areas and statutory requirements, such as the Marine Strategy Framework Directive and Marine and Climate Acts.

The shelf seas are highly productive compared to the open ocean, a productivity that underpins more than 90 per cent of global fisheries. Their importance to society extends beyond food production to include issues of biodiversity, carbon cycling and storage, waste disposal, nutrient cycling, recreation and renewable energy resources.

The shelf seas have been estimated to be the most valuable biome on Earth, but they are under considerable stress, as a result of anthropogenic nutrient loading, overfishing, habitat disturbance, climate change and other impacts.

However, even within the relatively well-studied European shelf seas, fundamental biogeochemical processes are poorly understood. For example: the role of shelf seas in carbon storage; in the global cycles of key nutrients (nitrogen, phosphorus, silicon and iron); and in determining primary and secondary production, and thereby underpinning the future delivery of many other ecosystem services.

Improved knowledge of such factors is not only required by marine policymakers; it also has the potential to increase the quality and cost-effectiveness of management decisions at the local, national and international levels under conditions of climate change.

The Shelf Sea Biogeochemistry research programme will take a holistic approach to the cycling of nutrients and carbon and the controls on primary and secondary production in UK and European shelf seas, to increase understanding of these processes and their role in wider biogeochemical cycles. It will thereby significantly improve predictive marine biogeochemical and ecosystem models over a range of scales.

The scope of the programme includes exchanges with the open ocean (transport on and off the shelf to a depth of around 500m), together with cycling, storage and release processes on the shelf slope, and air-sea exchange of greenhouse gases (carbon dioxide and nitrous oxide).

Further details are available on the SSB website.

Participants

15 different organisations are directly involved in research for SSB. These institutions are

  • Centre for Environment, Fisheries and Aquaculture Science (Cefas)
  • Meteorological Office
  • National Oceanography Centre (NOC)
  • Plymouth Marine Laboratory (PML)
  • Scottish Association for Marine Science (SAMS) / Scottish Marine Institute (SMI)
  • University of Aberdeen
  • University of Bangor
  • University of East Anglia (UEA)
  • University of Edinburgh
  • University of Essex
  • University of Liverpool
  • University of Oxford
  • Plymouth University
  • University of Portsmouth
  • University of Southampton

In addition, there are third party institutions carrying out sampling work for SSB, but who are not involved in the programme itself. These are:

  • The Agri-Food and Biosciences Institute (AFBI)
  • Irish Marine Institute (MI)
  • Marine Science Scotland (MSS)

Research details

Overall, five Work Packages have been funded by the SSB programme. These are described in brief below:

  • Work Package 1: Carbon and Nutrient Dynamics and Fluxes over Shelf Systems (CaNDyFloSS).
    This work package aims to perform a comprehensive study of the cycling of nutrients and carbon throughout the water column over the whole north-west European shelf. This will allow the fluxes of nutrients and carbon between the shelf and the deep ocean and atmosphere to be quantified, establishing the role of the north-west European continental shelf in the global carbon cycle.

  • Work Package 2: Biogeochemistry, macronutrient and carbon cycling in the benthic layer.
    This work package aims are to map the sensitivity and status of seabed habitats, based on physical conditions, ecological community structure and the size and dynamics of the nitrogen and carbon pools found there. This information will be used, in conjunction with some laboratory-based work, to generate an understanding of the potential impacts on the benthic community as a result of changing environmental conditions, such as rising CO2 levels.

  • Work Package 3: The supply of iron from shelf sediments to the ocean.
    The research for this work package addresses the question of how currents, tides, weather and marine chemistry allow new iron to be transported away from the shallow shelf waters around the United Kingdom (UK), to the nearby open ocean. This will ultimately allow an improved understanding of how the transport of iron in shelf waters and shelf sediments influences phytoplankton growth in open oceans. This in turn improves the understanding of carbon dioxide uptake by phytoplankton.

  • Work Package 4: Integrative modelling for Shelf Seas Biogeochemistry.
    The aim of this work package is the development of a new shelf seas biogeochemical model system, coupled to a state of the art physical model, that is capable of predicting regional impacts of environmental change of timescales from days to decades. It is envisaged that the combination of predictive tools and new knowledge developed in this work package will underpin development and implementation of marine policy and marine forecasting systems.

  • Work Package 5: Data synthesis and management of marine and coastal carbon (DSMMAC).
    This work package is funded by Defra and is also known by the name 'Blue Carbon'. The aim is to provide a process-based, quantitative assessment of the role of UK coastal waters and shelf seas in carbon storage and release, using existing data and understanding, and also emerging results from SSB fieldwork, experiments and modelling. Particular emphasis will be given to processes that may be influenced by human activities, and hence the opportunity for management interventions to enhance carbon sequestration.

Fieldwork and data collection

The campaign consists of the core cruises in the table below, to the marine shelf (and shelf-edge) of the Celtic Sea on board the NERC research vessels RRS Discovery and RRS James Cook. These cruises will focus on the physics and biogeochemistry of the benthic and pelagic zones of the water column, primarily around four main sampling sites in this area.

Cruise identifier Research ship Cruise dates Work packages
DY008 RRS Discovery March 2014 WP 2 and WP 3
JC105 RRS James Cook June 2014 WP 1, WP 2 and WP 3
DY026 RRS Discovery August 2014 WP1, WP 2 and WP 3
DY018 RRS Discovery November - December 2014 WP 1 and WP 3
DY021 (also known as DY008b) RRS Discovery March 2015 WP 2 and WP 3
DY029 RRS Discovery April 2015 WP 1 and WP 3
DY030 RRS Discovery May 2015 WP 2 and WP 3
DY033 RRS Discovery July 2015 WP 1 and WP 3
DY034 RRS Discovery August 2015 WP 2 and WP 3

Core cruises will be supplemented by partner cruises led by Cefas, MI, MSS, Bangor University and AFBI, spanning the shelf seas and shelf-edges around United Kingdom and Republic of Ireland.

Activities will include coring, Conductivity Temperature and Depth (CTD) deployments, Acoustic Doppler Current Profilers (ADCP) surveys, moorings and wire-walker deployments, benthic lander observatories, autonomous gliders and submersible surveys, Marine Snow Catcher particulate matter analysis, plankton net hauls, in-situ sediment flume investigations and laboratory incubations with core and sea water samples.


Shelf Sea Biogeochemistry (SSB) Programme Work Package 1: CaNDyFloSS

Carbon and Nutrient Dynamics and Fluxes over Shelf Systems (CaNDyFloSS) is a £2.76 million component of the Natural Environment Research Council (NERC) Shelf Sea Biogeochemistry (SSB) research programme, running from 2013 to 2017. It is jointly funded by NERC and the Department for Environment, Food and Rural Affairs (DEFRA). The aim of the research is to perform a comprehensive study of the cycling of nutrients and carbon throughout the water column over the whole north-west European shelf. This will allow the fluxes of nutrients and carbon between the shelf and the deep ocean and atmosphere to be quantified, establishing the role of the north-west European continental shelf in the global carbon cycle.

Background

Shelf seas are the primary regions of human marine resource exploitation, including both renewable and fossil fuel energy sources, recreation, trade and food production. They provide 90% of global fish catches which form an important source of food to much of the global population. They also play an important role in the ecosystem services provided by the oceans as a whole, in particular in storing carbon away from the atmosphere.

Physical and biochemical processes in shelf seas influence the removal of CO2 from the atmosphere and the subsequent storage of carbon in the deep ocean. Biological growth draws carbon out of the water, which is then replaced by carbon in CO2 from the atmosphere. In the shelf seas this growth is supported by terrestrial and open ocean sources of nutrients, implying intimate roles for both the terrestrial biosphere and the open ocean environment in regulating shelf sea climate services. The oceans can also be a major source or sink for other greenhouse gases, including nitrous oxide (N2O), with the shallow shelf sea thought to play a key role.

The spatial extent of the submerged continental shelves varies greatly. The NW European shelf sea is one of the largest and hence is likely to play a significant role in marine biogeochemical cycling, alongside providing a useful model for other systems. However, even in this relatively well studied region, there is a lack of detailed understanding of the principal controls on the cycling of carbon and the major nutrient elements, nitrogen, phosphorus and silicon. Consequently it is also difficult to predict how the cycling of these elements and hence the carbon removal they support may be altered by ongoing and potential future global change. This work package aims to address these uncertainties through a comprehensive study of the cycling of the major nutrients and carbon throughout the water column over the NW European shelf sea system.

Further details are available on the SSB website.

Participants

9 different organisations are directly involved in research for SSB Work Package 1. These institutions are

  • Centre for Environment, Fisheries and Aquaculture Science (Cefas)
  • National Oceanography Centre (NOC)
  • Plymouth Marine Laboratory (PML)
  • Scottish Association for Marine Science (SAMS) / Scottish Marine Institute (SMI)
  • University of Aberdeen
  • University of Bangor
  • University of East Anglia (UEA)
  • University of Liverpool
  • University of Southampton

In addition, there are third party institutions carrying out sampling work for SSB Work Package 1, but who are not involved in the programme itself. These are:

  • The Agri-Food and Biosciences Institute (AFBI)
  • Irish Marine Institute (MI)
  • Marine Science Scotland (MSS)

Objectives

Two overarching objectives are defined for this Work Package.

  • Objective 1: Estimate the size of the continental shelf carbon pump over the whole north-west European shelf.
    This will consist of two principal activities. (1) Over a 12 month period, observations of air-sea CO2 fluxes will be made to provide a synoptic estimate of the magnitude of carbon update by the whole shelf system. (2) Concentrations of carbon (C), nitrogen (N), phosphate (P) and silicate (Si) will be estimated in water flowing on and off the shelf. These estimates will be coupled to estimates of flow and dispersion along the shelf edge, through collaboration with the NERC Fluxes across Sloping Topography of the North East Atlantic (FASTNEt) programme to allow an observational estimate of the net off-shelf transport of C, N, P and Si.

  • Objective 2: Determine the relative importance of external nutrient sources and internal biogeochemical cycling in maintaining the continental shelf pump.
    Estimates of the flux of nutrients and carbon generated in Objective 1 will be used to determine the estimation of any excess of on-shelf nutrient supply, relative to that of carbon. Work Package 1 will then quantify the processes which govern internal biogeochemical cycling by measuring the uptake ratios of N, P, Si and C into phytoplankton and the element and energy balance of organic matter production by autotrophs. Potential modifications to the relative concentrations and uptake of C, N, P and Si in the thermocline and sediment food webs will also be assessed, as will the relative importance of microbial and zooplankton turnover in controlling C, N, P and Si.

Fieldwork and data collection

Data for Objective 1 will be provided using pCO2 systems aboard third party vessels and ferry boxes, along with measurements made through the FASTNEt programme and through the Work Package 1 process cruises detailed below. The third party cruises will be undertaken by Cefas, MI, MSS, University of Bangor and AFBI, spanning the shelf seas and shelf-edges around the United Kingdom and the Republic of Ireland.

The Work Package 1 process cruises will provide data for Objective 1 and Objective 2 and are listed in the table below. The study area is the marine shelf (and shelf-edge) of the Celtic Sea. Work will be carried out on board the NERC research vessels RRS Discovery and RRS James Cook. These cruises will focus on the physics and biogeochemistry of the benthic and pelagic zones of the water column, primarily around four main sampling sites in this area.

Cruise identifier Research ship Cruise dates Work packages
JC105 RRS James Cook June 2014 WP 1, WP 2 and WP 3
DY026 RRS Discovery August 2014 WP1, WP 2 and WP 3
DY018 RRS Discovery November - December 2014 WP 1 and WP 3
DY029 RRS Discovery April 2015 WP 1 and WP 3
DY033 RRS Discovery July 2015 WP 1 and WP 3

Activities will include Conductivity Temperature and Depth (CTD) deployments, Acoustic Doppler Current Profilers (ADCP) surveys, moorings and wire-walker deployments, autonomous gliders and submersible surveys, Marine Snow Catcher particulate matter analysis, plankton net hauls and laboratory incubations with sea water samples.


Data Activity or Cruise Information

Cruise

Cruise Name DY021
Departure Date 2015-03-01
Arrival Date 2015-03-26
Principal Scientist(s)E Malcolm S Woodward (Plymouth Marine Laboratory)
Ship RRS Discovery

Complete Cruise Metadata Report is available here


Fixed Station Information

Fixed Station Information

Station NameShelf Seas Biogeochemistry Fixed Station East of Haig Frais
CategoryOffshore area
Latitude50° 35.49' N
Longitude7° 1.06' W
Water depth below MSL106.0 m

Shelf Seas Biogeochemistry Fixed Station East of Haig Frais

This station is one of four mooring sites located on the continental shelf of the Celtic Sea and maintained during the Shelf Seas Biogeochemistry project. The station has a mean water depth 109 m at the following co-ordinates:

Box Corner Latitude Longitude
North-west corner 50.59708° -7.02996°
South-east corner 50.58593° -7.00356°

The position of this station relative to the other Shelf Seas Biogeochemistry sites can be seen from the figure below.

BODC image

Sampling History

DY008 JC105 DY026 DY018
CTD casts 1 2 1 -
STD casts - 1 1 -
Underway samples - 1 1 samples measured for nutrients, oxygen, chlorophyll and SPM
PML drifter buoy - - 1 -

Mooring deployments

Latitude Longitude Water depth (m) Moored instrument Deployment date Recovery date Deployment cruise Recovery cruise Comments
50.5961° -7.0221° 109 Cefas mini-lander 22-03-2014 19:43 UTC 16-06-2014 15:22 UTC DY008 JC105 -
50.5957° -7.0223° 109 Cefas mini-lander 16-06-2014 17:32 UTC 19-08-2014 08:45 UTC JC105 DY026 -
50.5930° -7.0210° 109 Cefas mini-lander 20-08-2014 18:23 UTC - DY026 - -

Related Fixed Station activities are detailed in Appendix 1


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

Appendix 1: Shelf Seas Biogeochemistry Fixed Station East of Haig Frais

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

If you are interested in these series, please be aware we offer a multiple file download service. Should your credentials be insufficient for automatic download, the service also offers a referral to our Enquiries Officer who may be able to negotiate access.

Series IdentifierData CategoryStart date/timeStart positionCruise
1371500CTD or STD cast2014-03-22 21:02:0050.5971 N, 7.02993 WRRS Discovery DY008
1336631Water sample data2014-03-22 21:04:0050.59708 N, 7.02996 WRRS Discovery DY008
1372644CTD or STD cast2014-06-16 13:38:0050.59278 N, 7.02952 WRRS James Cook JC105
2103750Water sample data2014-06-16 13:38:3050.59176 N, 7.02957 WRRS James Cook JC105
2108011Water sample data2014-06-16 13:38:3050.59176 N, 7.02957 WRRS James Cook JC105
2143021Water sample data2014-06-16 13:38:3050.59176 N, 7.02957 WRRS James Cook JC105
2103762Water sample data2014-06-16 18:09:0050.59383 N, 7.0235 WRRS James Cook JC105
2108023Water sample data2014-06-16 18:09:0050.59383 N, 7.0235 WRRS James Cook JC105
2143033Water sample data2014-06-16 18:09:0050.59383 N, 7.0235 WRRS James Cook JC105
1372656CTD or STD cast2014-06-16 18:10:0050.59381 N, 7.02354 WRRS James Cook JC105
1373383CTD or STD cast2014-08-18 17:00:0050.58995 N, 7.02363 WRRS Discovery DY026B
2127819Water sample data2014-08-18 17:25:0050.58996 N, 7.02362 WRRS Discovery DY026B
2127291Water sample data2015-03-17 10:58:3050.59269 N, 7.01282 WRRS Discovery DY021
1624829CTD or STD cast2015-05-15 06:10:0050.59003 N, 7.02328 WRRS Discovery DY030
2132441Water sample data2015-05-15 06:20:3050.59003 N, 7.02329 WRRS Discovery DY030
1624830CTD or STD cast2015-05-16 07:28:0050.59486 N, 7.02463 WRRS Discovery DY030
2132453Water sample data2015-05-16 07:40:0050.59481 N, 7.02464 WRRS Discovery DY030
1721519CTD or STD cast2015-08-30 10:07:0050.59547 N, 7.01865 WRRS Discovery DY034