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Metadata Report for BODC Series Reference Number 949712

Metadata Summary

Data Description

Data Category CTD or STD cast
Instrument Type
SeaTech transmissometer  transmissometers
Sea-Bird SBE 13 Dissolved Oxygen Sensor  dissolved gas sensors
Sequoia Laser In-Situ Sediment Size Transmissometer  transmissometers; water temperature sensor; in-situ particle sizers
Sea-Bird SBE 911plus CTD  CTD; water temperature sensor; salinity sensor
LI-COR LI-192 PAR sensor  radiometers
Turner Designs SCUFA II Submersible Fluorometer  fluorometers
Instrument Mounting research vessel
Originating Country United Kingdom
Originator Prof Matt Palmer
Originating Organization Proudman Oceanographic Laboratory (now National Oceanography Centre, Liverpool)
Processing Status banked
Online delivery of data Download available - Ocean Data View (ODV) format
Project(s) Coastal Observatory
Oceans 2025
Oceans 2025 Theme 10
Oceans 2025 Theme 10 SO11

Data Identifiers

Originator's Identifier C006
BODC Series Reference 949712

Time Co-ordinates(UT)

Start Time (yyyy-mm-dd hh:mm) 2008-10-22 19:05
End Time (yyyy-mm-dd hh:mm) -
Nominal Cycle Interval 0.5 decibars

Spatial Co-ordinates

Latitude 53.44867 N ( 53° 26.9' N )
Longitude 3.50467 W ( 3° 30.3' W )
Positional Uncertainty 0.05 to 0.1 n.miles
Minimum Sensor or Sampling Depth 2.23 m
Maximum Sensor or Sampling Depth 18.09 m
Minimum Sensor or Sampling Height 1.51 m
Maximum Sensor or Sampling Height 17.37 m
Sea Floor Depth 19.6 m
Sea Floor Depth Source -
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


BODC CODERankUnitsTitle
ATTNMR011per metreAttenuation (red light wavelength) per unit length of the water body by 20 or 25cm path length transmissometer
DOXYPR011Micromoles per litreConcentration of oxygen {O2 CAS 7782-44-7} per unit volume of the water body [dissolved plus reactive particulate phase] by in-situ Beckmann probe
FVLTWS011VoltsRaw signal (voltage) of instrument output by linear-response chlorophyll fluorometer
IRRDUV011MicroEinsteins per square metre per secondDownwelling vector irradiance as photons of electromagnetic radiation (PAR wavelengths) in the water body by cosine-collector radiometer
NVLTLS011VoltsRaw signal (voltage) of instrument output by LISST scatterometer
OXYSBB011PercentSaturation of oxygen {O2 CAS 7782-44-7} in the water body [dissolved plus reactive particulate phase] by in-situ Beckmann probe and computation from concentration using Benson and Krause algorithm
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
PSALCU011DimensionlessPractical salinity of the water body by CTD and computation using UNESCO 1983 algorithm and NO calibration against independent measurements
SIGTPR011Kilograms per cubic metreSigma-theta of the water body by CTD and computation from salinity and potential temperature using UNESCO algorithm
TEMPCC011Degrees CelsiusTemperature of the water body by CTD and verification against independent measurements
TVLTZR011VoltsRaw signal (voltage) of instrument output by red light transmissometer

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

Problem Report

Dissolved Oxygen

All data from this channel should be used with caution as the values measured were unrealistic during this and several other cruises. Readings taken by the probe indicated that the sensor was constantly saturated. It is advised that the data should only be used for relative comparisons.

Data quality notes

LISST transmission and scattering

Users should be aware that the clear water values measured on different cruises are observed to increase and decrease at times, which is not consistent behaviour. In addition, the clear water scattering values are also sometimes less than and sometimes greater than those measured by the manufacturer at the time of last calibration (October 2006). This may be due to a problem with the instrument or the method in which the clear water values are measured.

Salinity and Temperature

All salinity data are un-calibrated as there are insufficient independent salinity data to perform a comparison.

Anomalous salinity and temperature data were flagged from the surface to beyond the mid-point of the water body in series 949736 and 949748. These flagged data were excluded from the bin-averaging process, resulting in null values. As oxygen saturation, potential temperature and sigma-theta all require salinity and/or temperature in order to be derived, these parameters were therefore flagged null in the same bins.

In many cases, it was not possible to clearly determine which data points were suspect, so there may be bad data present which have not been flagged. Users are advised to treat these data with caution.

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 Electronics SBE13 Dissolved Oxygen Sensor

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

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

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

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


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

2 s at 25°C

5 s at 0°C

Depth range

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

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

105000 m (SBE 13B- housing in titanium)

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

Prince Madog Cruise PD33_08 CTD Instrumentation

The CTD unit was a Sea-Bird Electronics 911plus system (SN P23655-0620), with dissolved oxygen sensor. The CTD was fitted with a red (660 nm) beam transmissometer, a fluorometer, a Sequoia Scientific Laser In-Situ Scattering and Transmissometry (LISST) particle analyser and a LI-COR Underwater Quantum Sensor. Also attached was a Sea-Bird SBE-35 Temperature Logger to supply an independent check of temperature. All instruments were attached to a Sea-Bird SBE 32 compact carousel. The table below lists more detailed information about the various sensors.

Sensor Model Serial Number Calibration (UT) Comments
Pressure transducer Paroscientific Digiquartz 42K-105 76076 2004-01-21 -
Conductivity sensor SBE 4 2543 2004-01-14 -
Temperature sensor SBE 3 P4100 2004-01-21 -
Dissolved oxygen SBE 13 Beckmann 130580 2004-01-05 -
Transmissometer (660 nm) SeaTech T1000 T1021 1998-03-03 0.2 m path
Fluorometer Turner SCUFA II 262 - -
LISST 25A 120 2006-10-26 Range: 1.25 - 250 µm
LI-COR (contains CEFAS in-house electronics) LI-192SB CEFAS #26 - -
Temperature Logger SBE-35 0041 2005-05-29 -

Change of sensors during cruise: None reported.

Sampling device

Rosette sampling system equipped with 5 l sampling bottles (Sea-Bird Improved PVC Sample Bottles based on design of Ocean Test Equipment Inc. model 110 bottle).

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 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.

Turner Designs Self-Contained Underwater Fluorescence Apparatus (SCUFA)

The Turner Designs SCUFA is a submersible fluorometer for chlorophyll and dye tracing operations that has been designed to operate in a wide range of concentrations, environmental conditions as well as operational modes (profiling or moored deployments). The instrument includes an integrated temperature probe and software which allow for automatic correction of fluorescence data from temperature effects. The superior ambient light rejection eliminates the effects of sunlight and allows the SCUFA to be used in surface waters without the need for external pumps or light shields.

Each instrument can be customised to meet user requirements. Users can choose one of the following channels: chlorophyll a, cyanobacteria (phycocyanin or phycoerythrin pigments), rhodamine WT, fluorescein and turbidity. Instrument options include turbidity, internal data logging and automatic temperature correction.

Three versions of the SCUFA are available: SCUFA I, II and III. SCUFA I and II are used for chlorophyll a applications, while SCUFA III is used for Rhodamine WT. Models II and III include a turbidity channel that is not present on model I. The SCUFA has been out of production since 2008.


Depth rating 600 m
Detector Photodiode
Temperature range -2 to 40°C
Maximum sampling rate

1Hz- digital

5 Hz- analog


12 bit- digital

1.2 mV- analog

Dynamic Range
Fluorescence 4 orders of magnitude
Turbidity 3 orders of magnitude

The table below presents the specifications for the different channels.

Specifications Chlorophyll Cyanobacteria Rhodamine WT/Fluorescein
Light source Blue

Orange- PC

Blue- PE

Excitation/Emission 460/685

595/670 (phycocyanin, PC)

528/573 (phycoerythrin, PE)

530/600 (rhodamine)

490/580 (fluorescein)

Minimum detection Limit
Fluorescence 0.02 µg L-1 150 cells mL-1 0.04 ppb
Turbidity 0.05 NTU 0.05 NTU 0.05 NTU

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

LI-COR LI-192 Underwater Quantum Sensor

The LI-192 Underwater Quantum Sensor is used to measure photosynthetic photon flux density and is cosine corrected. The sensor is often referred to as LI-192SA or LI-192SB (the LI-192SB model was superseded by LI-192SA). One of the main differences is that the LI-192SA model includes a built-in voltage output for interfacing with NexSens iSIC and SDL data loggers.

Sensor specifications, current at January 2012, are given in the table below. More information can be found in the manufacturer's LI-192SA andLI-192SB specification sheets.

Sensor Specifications

(Specifications apply to both models unless otherwise stated)

Absolute Calibration ± 5 % in air traceable to NBS.
Sensitivity Typically 3 µA per 1000 µmol s-1 m-2 for LI-192SB and 4 µA per 1000 µmol s-1 m-2 for LI-192SA in water.
Linearity Maximum deviation of 1 % up to 10,000 µmol s-1 m-2.
Stability < ± 2 % change over a 1 year period.
Response Time 10 µs.
Temperature Dependence ± 0.15 % per °C maximum.
Cosine Correction Optimized for both underwater and atmospheric use.
Azimuth < ± 1 % error over 360 ° at 45 ° elevation.
Detector High stability silicon photovoltaic detector (blue enhanced).
Sensor Housing Corrosion resistant metal with acrylic diffuser for both saltwater and freshwater applications. Waterproof to withstand 800 psi (5500 kPa) (560 meters).

SeaTech Transmissometer


The transmissometer is designed to accurately measure the the amount of light transmitted by a modulated Light Emitting Diode (LED) through a fixed-length in-situ water column to a synchronous detector.


  • Water path length: 5 cm (for use in turbid waters) to 1 m (for use in clear ocean waters).
  • Beam diameter: 15 mm
  • Transmitted beam collimation: <3 milliradians
  • Receiver acceptance angle (in water): <18 milliradians
  • Light source wavelength: usually (but not exclusively) 660 nm (red light)


The instrument can be interfaced to Aanderaa RCM7 current meters. This is achieved by fitting the transmissometer in a slot cut into a customized RCM4-type vane.

A red LED (660 nm) is used for general applications looking at water column sediment load. However, green or blue LEDs can be fitted for specilised optics applications. The light source used is identified by the BODC parameter code.

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

Sequoia Laser In-situ Sediment Size Transmissometer (LISST)

The Sequoia LISST measures particle size distribution of suspended sediments by laser diffraction. This technique allows particles of various compositions to be measured with a single device and, because the particle volume is roughly of the same order for all sizes, the required dynamic range of the sensors is reduced compared with single-particle counters.

The instrument includes optics for producing a collimated laser beam, a detector array, electronics for signal amplification and processing, a data storage and scheduling computer and a battery system. The primary measurement is the scattering of laser light at a number of angles, which is mathematically inverted to give a grain size distribution, and also scaled to obtain the volume scattering function. The size distribution is presented as concentration in each of 32 logarithmically-spaced grain-size class bins. Optical transmission, water depth and temperature are recorded as supporting measurements.

Several models are available and although the principals of operation are the same, their specifications vary slightly. The specifications for model LISST-100 are provided below.


Optical path length

5 cm (standard)

2.5 cm (optional)

Optical transmission 12 bit resolution
Particle size range

Type B: 1.25 to 250 micron diameter

Type C: 2.5 to 500 micron diameter

Resolution 32 size classes, log-spaced
VSF angle range 1.7 to 340 mrad
Maximum sample speed 4 size distributions per second (standard)
Temperature range -10 to 45 °C
Temperature resolution 0.01 °C
Pressure range 0 to 300 m
Pressure resolution 8 cm

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

Prince Madog Cruise PD33_08 CTD Processing

Originator's Data Processing

  • Sampling Strategy

    In total, 9 CTD profiles were performed during the cruise throughout Liverpool Bay. The data from cast 4 were deemed erroneous by the data originator due to winchman error and were therefore excluded from the dataset. Rosette bottles were fired throughout the water column on the upcast of most profiles. Independent temperature data were recorded at the time of each bottle firing.

    Data were measured at 24 Hz, averaged to 1 Hz by the deck unit and logged onto a PC running SEASAVE, Sea-Bird's data acquisition software. The raw Sea-Bird data, configuration and bottle files were supplied to BODC for further processing.

BODC Processing

  • Data Processing

    The raw CTD files were processed through the Sea-Bird SBE Data Processing software version 7.18b. Binary (.HEX) files were converted to engineering units and ASCII format (.CNV) using the DATCNV program.

    Sea-Bird bottle files (.BTL), with information on pressure and other logged readings at the time of bottle firing, were also generated during the data conversion process.

    WILDEDIT was not run on the data as no pressure spikes were present in the casts. FILTER was run on the pressure channel using the recommended time filter of 0.15 s.

    Sea-Bird software program ALIGN CTD was run to advance conductivity by 0 s and oxygen by 3 s (within the typical range given in the Sea-Bird manual). No adjustment was made to the temperature channel as the fast sensor response time renders this unnecessary, according to the Sea-Bird literature.

    To compensate for conductivity cell thermal mass effects, the data files were run through CELLTM, using alpha = 0.03, 1/beta = 7, typical values for this CTD model given in the Sea-Bird literature. Next, a minimum CTD velocity of 0.0 m s-1 was used for LOOP EDIT in order to exclude scans where the CTD was travelling backwards due to ship's heave. Salinity, density (Sigma-theta kg m-3) and oxygen concentration (ml l-1) were then calculated and added to the output files using the DERIVE program. Finally, the first oxygen concentration channel and first salinity channel (both generated by DATCNV using data un-adjusted by ALIGN CTD and CELLTM) were dropped using STRIP.

  • Reformatting

    The data were converted from ASCII format into BODC internal format (QXF) using BODC transfer function 357. The following table shows how the variables within the ASCII files were mapped to appropriate BODC parameter codes:

    Originator's Parameter Name Units Description BODC Parameter Code Units Comments
    Pressure, Digiquartz dbar CTD pressure PRESPR01 dbar -
    Conductivity S m-1 Electrical conductivity of the water body by CTD CNDCST01 S m-1 Not banked by BODC. These data are used as an intermediate step in calculation of PSALCU01.
    Oxygen, Beckman/YSI ml l-1 Dissolved oxygen concentration from Beckmann probe DOXYPR01 µmol l-1 ml l-1 * 44.66
    Salinity - Practical salinity of the water body by CTD PSALCU01 - -
    Temperature [ITS-90] °C Temperature of water column by CTD TEMPCU01 °C Not banked by BODC. Data are un-calibrated. Used as source data for TEMPCC01
    Voltage 2 Un-adjusted volts Voltage from CTD PAR Sensor LVLTLD01 Un-adjusted volts Not banked by BODC. These data are used as source data for the calculation of IRRDUV01.
    Voltage 3 Un-adjusted volts Beam transmissometer voltage TVLTCR01 Un-adjusted volts Not banked by BODC. These data are used as source data for the calculation of ATTNMR01.
    Voltage 4 Un-adjusted volts Voltage from CTD SCUFA Turner fluorometer FVLTWS01 Un-adjusted volts -
    Voltage 6 Un-adjusted volts LISST scatterometer voltage output NVLTLS01 Un-adjusted volts -
    Voltage 7 Un-adjusted volts LISST transmissometer voltage output TVLTZR01 Un-adjusted volts -
    - - Potential temperature POTMCV01 °C Generated by BODC using UNESCO Report 38 (1981) algorithm with parameters PSALCC01 and TEMPCC01
    - - Sigma-theta SIGTPR01 kg m-3 Generated by BODC using the Fofonoff and Millard (1982) algorithm
    - - PAR IRRDUV01 µE m-2 s-1 Generated by BODC from calibration of LVLTLD01
    - - Beam Attenuation ATTNMR01 m-1 Generated by BODC from calibration of TVLTCR01
    - - Temperature TEMPCC01 °C Generated by BODC from calibration of TEMPCU01
    - - Oxygen saturation OXYSBB01 % Generated by BODC during transfer using the Benson and Krause (1984) algorithm.
  • References

    Benson, B.B. and Krause, D., 1984. The concentration and isotopic fractionation of oxygen dissolved in freshwater and seawater in equilibrium with the atmosphere. Limnol. Oceanogr., 29(3), 620-632

    Fofonoff, N.P. and Millard, R.C., 1983. Algorithms for computations of fundamental properties of seawater. UNESCO Technical Papers in Marine Science No. 44, 53pp.

    UNESCO, 1981. Background papers and supporting data on the International Equation of State of Seawater 1980. UNESCO Technical Papers in Marine Science No. 38, 192pp

  • Screening

    Reformatted CTD data were transferred onto a graphics work station for visualisation using the in-house editor EDSERPLO. Downcasts and upcasts were differentiated and the limits manually flagged. No data values were edited or deleted. Flagging was achieved by modification of the associated quality control flag to 'M' for suspect values and 'N' for nulls.

  • Banking

    Once quality control screening was complete, CTD downcasts for all casts were binned against pressure at 0.5 dbar increments. During binning, BODC exclude flagged data and generate interpolated values to fill in gaps in the increment sequence, where necessary. Finally, the CTD downcasts were banked.

Field Calibrations

  • Salinity

    As only 6 independent salinity samples were obtained from the CTD rosette it was not possible to calibrate the CTD salinity data. For information, the mean offset between the bottle salinity and CTD salinity was 0.053, with a standard deviation of 0.034342.

  • Temperature

    44 independent temperature values were compared to pressure and CTD temperature. The temperature offset (SBE-35 temperature - CTD temperature) was found, using regression analysis, not to be significantly related to SBE-35 temperature at the 95% confidence level. The mean offset is -0.001636 °C and the standard deviation for this dataset is 0.003012 °C. This is at the lowest level of accuracy for both the SBE-35 and Sea-Bird 911plus CTD (+/- 0.001 °C). Therefore, there was no adjustment to the CTD temperature resulting from the application of manufacturer's coefficients during initial processing.

  • Pressure

    There were no casts where the CTD pressure was logging in air. No adjustments were made to the values resulting from application of manufacturer's coefficients during the intial processing.

  • Beam attenuation

    Coefficients M and B were calculated, allowing calibration of the transmissometer with air readings taken during the cruise. M and B are calculated according to SBE Application Note No. 7:

    M = (Tw/W0)*(A0-Y0)/(A1-Y1)
    B= -M*Y1

    Where Tw is the percent transmission for pure water for the instrument (92.98%); W0 is the voltage output in pure water (4.649 volts); A0 is the manufacturer's air voltage (4.661 volts); Y0 is the manufacturer's blocked path voltage (0.000 volts); A1 is the cruise maximum air voltage (4.40415 volts); Y1 is the current blocked path voltage (0.00 volts). For this cruise, M and B were calculated to be 21.1664 and 0, respectively.

    M and B are then inserted into the following equations (from SBE Application Note No. 7) to obtain calibrated beam attenuation:

    Light transmission [%] = (M * voltage output) + B
    Beam attenuation coefficient c = - (1/z) * ln (light transmission [decimal])

    M and B are the calibration coefficients, z is the transmissometer path length (0.2 m), light transmission[decimal] is light transmission [%] divided by 100, c = beam attenuation (m-1)

  • Dissolved oxygen

    These data are currently un-calibrated.

  • Fluorescence

    These data are currently un-calibrated.

  • LISST transmission and scattering

    The data are currently supplied as voltages due to concerns about the observed variability in the clean water readings over time. With reliable clean water readings, the voltages can be calibrated to give optical transmission, beam attenuation, total volume concentration and Sauter mean diameter according to the following manufacturer's constants and calculations:

    Optical Transmission = b = (VT-VToff)/(VTO-VToff)

    Beam attenuation = -ln(b)/0.025 - units are metres-1, assumes 25mm path

    Total volume concentration = TV = cal*[((VS-VSoff)/b)-(VSO-VSoff)] - units are µl l-1

    Sauter mean diameter = SMD = a*[TV/(-ln(b)] - units are µm

    Where, the coefficients supplied here are from clear water readings taken during the most recent manufacturer calibration (October 2006) as follows:

    • VT = measured transmission output V
    • VToff = transmission output offset = 0.007 V
    • VTO = clear water transmission output = 2.828 V
    • cal = total volume concentration calibration constant = 630
    • VS = measured scattering output V
    • VSoff = scattering output offset = 0.004 V
    • VSO = clear water scattering output = 0.155 V
    • a = Sauter mean diameter calibration constant = 0.075

    Ideally the manufacturer's clear water values should be substituted by values determined by the LISST calibration cast, during which the instrument is placed in a tank of clean water. However, there is suspicion that these values may not be accurate.

    The clean water transmission and scattering voltages can be seen to both increase and decrease with time, showing inconsistency in either the instrument performance or the calibration dip method. Therefore, manufacturer's values have been quoted along with values measured by the instrument during previous cruises since the last manufacturer's calibration. Users are advised to use their own discretion in deciding which coefficients to apply.

    Date (UT) Cruise VT VS
    2006-12-12 PD37_06 2.723 0.156
    2007-02-12 PD02_07 2.74 0.154
    2007-03-12 PD04_07 2.672 0.17
    2007-04-15 PD06_07 2.72207 0.16728
    2007-05-14 PD09_07 2.70208 0.16606
    2007-06-20 PD13_07 2.47863 0.20879
    2007-07-25 PD16_07 2.42979 0.21123
    2007-08-28 PD20_07 2.45543 0.20757
    2007-10-02 PD23_07 Not recorded Not recorded
    2007-11-20 PD27_07 2.70696 0.15751
    2008-01-08 PD01_08 2.68742 0.15873
    2008-02-12 PD01_08 Not recorded Not recorded
    2008-03-10 PD07_08 2.66545 0.15873
    2008-04-15 PD09_08 2.69353 0.15873
    2008-05-12 PD14_08 2.62149 0.18315
    2008-06-24 PD19_08 Not recorded Not recorded
    2008-07-29 PD23_08 2.60562 0.17338
    2008-10-17 PD33_08 2.6862 0.15995
  • PAR

    During instrument deployment, no effort was made to avoid data collection possibly being affected by ship shadowing. The LI-COR LI-192SB sensor number 26 was calibrated from raw voltages using the CEFAS supplied equation:

    PAR = 0.135278*exp(volts*3.4544)

Project Information

Oceans 2025 Theme 10

Oceans 2025 is a strategic marine science programme, bringing marine researchers together to increase people's knowledge of the marine environment so that they are better able to protect it for future generations.

Theme 10: Integration of Sustained Observations in the Marine Environment spans all marine domains from the sea-shore to the global ocean, providing data and knowledge on a wide range of ecosystem properties and processes (from ocean circulation to biodiversity) that are critical to understanding Earth system behaviour and identifying change. They have been developed not merely to provide long-term data sets, but to capture extreme or episodic events, and play a key role in the initialisation and validation of models. Many of these SOs will be integrated into the newly developing UK Marine Monitoring Strategy - evolving from the Defra reports Safeguarding our Seas (2002) and Charting Progress (2005), thus contributing to the underpinning knowledge for national marine stewardship. They will also contribute to the UK GOOS Strategic Plan (IACMST, 2006) and the Global Marine Assessment.


Oceans 2025 - The NERC Marine Centres' Strategic Research Programme 2007-2012

Who funds the programme?

The Natural Environment Research Council (NERC) funds the Oceans 2025 programme, which was originally planned in the context of NERC's 2002-2007 strategy and later realigned to NERC's subsequent strategy (Next Generation Science for Planet Earth; NERC 2007).

Who is involved in the programme?

The Oceans 2025 programme was designed by and is to be implemented through seven leading UK marine centres. The marine centres work together in coordination and are also supported by cooperation and input from government bodies, universities and other partners. The seven marine centres are:

  • National Oceanography Centre, Southampton (NOCS)
  • Plymouth Marine Laboratory (PML)
  • Marine Biological Association (MBA)
  • Sir Alister Hardy Foundation for Marine Science (SAHFOS)
  • Proudman Oceanographic Laboratory (POL)
  • Scottish Association for Marine Science (SAMS)
  • Sea Mammal Research Unit (SMRU)

Oceans2025 provides funding to three national marine facilities, which provide services to the wider UK marine community, in addition to the Oceans 2025 community. These facilities are:

  • British Oceanographic Data Centre (BODC), hosted at POL
  • Permanent Service for Mean Sea Level (PSMSL), hosted at POL
  • Culture Collection of Algae and Protozoa (CCAP), hosted at SAMS

The NERC-run Strategic Ocean Funding Initiative (SOFI) provides additional support to the programme by funding additional research projects and studentships that closely complement the Oceans 2025 programme, primarily through universities.

What is the programme about?

Oceans 2025 sets out to address some key challenges that face the UK as a result of a changing marine environment. The research funded through the programme sets out to increase understanding of the size, nature and impacts of these changes, with the aim to:

  • improve knowledge of how the seas behave, not just now but in the future;
  • help assess what that might mean for the Earth system and for society;
  • assist in developing sustainable solutions for the management of marine resources for future generations;
  • enhance the research capabilities and facilities available for UK marine science.

In order to address these aims there are nine science themes supported by the Oceans 2025 programme:

  • Climate, circulation and sea level (Theme 1)
  • Marine biogeochemical cycles (Theme 2)
  • Shelf and coastal processes (Theme 3)
  • Biodiversity and ecosystem functioning (Theme 4)
  • Continental margins and deep ocean (Theme 5)
  • Sustainable marine resources (Theme 6)
  • Technology development (Theme 8)
  • Next generation ocean prediction (Theme 9)
  • Integration of sustained observations in the marine environment (Theme 10)

In the original programme proposal there was a theme on health and human impacts (Theme 7). The elements of this Theme have subsequently been included in Themes 3 and 9.

When is the programme active?

The programme started in April 2007 with funding for 5 years.

Brief summary of the programme fieldwork/data

Programme fieldwork and data collection are to be achieved through:

  • physical, biological and chemical parameters sampling throughout the North and South Atlantic during collaborative research cruises aboard NERC's research vessels RRS Discovery, RRS James Cook and RRS James Clark Ross;
  • the Continuous Plankton Recorder being deployed by SAHFOS in the North Atlantic and North Pacific on 'ships of opportunity';
  • physical parameters measured and relayed in near real-time by fixed moorings and ARGO floats;
  • coastal and shelf sea observatory data (Liverpool Bay Coastal Observatory (LBCO) and Western Channel Observatory (WCO)) using the RV Prince Madog and RV Quest.

The data is to be fed into models for validation and future projections. Greater detail can be found in the Theme documents.

Oceans 2025 Theme 10, Sustained Observation Activity 11: Liverpool Bay and Irish Sea Coastal Observatory

Sustained, systematic observations of the ocean and continental shelf seas at appropriate time and space scales allied to numerical models are key to understanding and prediction. In shelf seas these observations address issues as fundamental as 'what is the capacity of shelf seas to absorb change?' encompassing the impacts of climate change, biological productivity and diversity, sustainable management, pollution and public health, safety at sea and extreme events. Advancing understanding of coastal processes to use and manage these resources better is challenging; important controlling processes occur over a broad range of spatial and temporal scales which cannot be simultaneously studied solely with satellite or ship-based platforms.

Considerable effort has been spent by the Proudman Oceangraphic Laboratory (POL) in the years 2001 - 2006 in setting up an integrated observational and now-cast modelling system in Liverpool Bay (see Figure), with the recent POL review stating the observatory was seen as a leader in its field and a unique 'selling' point of the laboratory. Cost benefit analysis (IACMST, 2004) shows that benefits really start to accrue after 10 years. In 2007 - 2012 exploitation of (i) the time series being acquired, (ii) the model-data synthesis and (iii) the increasingly available quantities of real-time data (e.g. river flows) can be carried out through Sustained Observation Activity (SO) 11, to provide an integrated assessment and short term forecasts of the coastal ocean state.

BODC image

Overall Aims and Purpose of SO 11

  • To continue and enlarge the scope of the existing coastal observatory in Liverpool Bay to routinely monitor the northern Irish Sea
  • To develop the synthesis of measurements and models in the coastal ocean to optimize measurement arrays and forecast products. Driving forward shelf seas' operational oceanography with the direct objective of improving the national forecasting capability, expressed through links to the National Centre for Ocean Forecasting (NCOF)
  • To exploit the long time-series of observations and model outputs to: a) identify the roles of climate and anthropogenic inputs on the coastal ocean's physical and biological functioning (including impacts of nutrient discharges, offshore renewable energy installations and fishing activity) taking into consideration the importance of events versus mean storms / waves, river discharge / variable salinity stratification / horizontal gradients; b) predict the impacts of climate change scenarios; and c) provide new insights to Irish Sea dynamics for variables either with seasonal cycles and interannual variability, or which show weak or no seasonal cycles
  • To provide and maintain a 'laboratory' within which a variety of observational and model experiments can be undertaken (Oceans 2025 Themes 3, 6, 8, 9), including capture of extreme events
  • Demonstrate the value of an integrated approach in assessment and forecasting
  • Demonstrate the coastal observatory as a tool for marine management strategies through collaboration with the Environment Agency (EA), Department for Environment, Food and Rural Affairs (DEFRA), Joint Nature Conservation Commmittee (JNCC), English Nature (EN), Department of Agriculture and Rural Development (DARD), and Local Authorities, providing management information pertinent to policy (e.g. Water Framework Directive)

Measurement and Modelling Activities

  • East Mooring Site: Bottom frame with full suite of physical measurements (high frequency Acoustic Doppler Current Profiler (ADCP), conductivity, temperature, turbidity and fluorescence), a Centre for Environment, Fisheries and Aquaculture Science (CEFAS) directional wavebuoy, and a CEFAS Smartbuoy collecting surface properties including salinity, temperature, turbidity, nutrients, irradiance and chlorophyll. All transmit data in real-time via Orbcomm. The Smartbuoy also collects daily water samples.
  • West Mooring Site: Bottom frame with full suite of physical measurements (high frequency ADCP, conductivity, temperature, turbidity and fluorescence), CEFAS Smartbuoy.
  • Spatial Survey: Four - six week intervals (determined by biofouling of optical sensors). Spatial surveys comprise of vertical profiles of CTD, suspended particulate material (SPM), some bed sediment sampling and surface and bed nutrients, phytoplankton, zooplankton.
  • Ferry: The Birkenhead - Belfast ferry samples near surface (5 m depth) temperature, salinity, turbidity, chlorophyll, with data transmitted by Orbcomm. The route is scientifically varied passing through six completely different hydrodynamic regions, which significantly impact on their ecological function.
  • Tide gauges: Real-time data are obtained from tide gauges operated by Mersey Docks and Harbour Company (MDHC) and the UK tide gauge network.
  • Satellite imagery: Weekly composite satellite data, Advanced Very High Resolution Radiometer (AVHRR) sea surface temperature (SST) and ocean colour (chlorophyll and suspended sediment), are provided by the Remote Sensing Data Analysis Service (RSDAS) based at Plymouth Marine Laboratory (PML).
  • HF radar: A phased array HF radar system (a 12-16MHz WERA HF radar) measuring surface currents and waves with maximum range 75km at a resolution of 4km for sea surface currents and for 2-D wave spectra.
  • Meteorology station: With web camera, located on Hilbre Island at the mouth of the Dee Estuary
  • Operational models: The Coastal Observatory uses Proudman Oceanographic Laboratory Coastal Ocean Modelling System (POLCOMS), which is part of Oceans 2025 Theme 9.

More detailed information on this Work Package is available at pages 32 - 35 of the official Oceans 2025 Theme 10 document: Oceans 2025 Theme 10



IACMST., 2004. The Economics of Sustained Marine Measurements. IACMST Information Document, N0.11, Southampton: IACMST, 96 pp

Proudman Oceanographic Laboratory Coastal Observatory

The Coastal Observatory was established by Proudman Oceanographic Laboratory as a coastal zone real time observing and monitoring system. The main objective is to understand a coastal sea's response both to natural forcing and to the consequences of human activity. Near real-time measurements will be integrated with coupled models into a pre-operational coastal prediction system whose results will be displayed on the World Wide Web.

The Observatory is expected to grow and evolve as resources and technology allow, all the while building up long time series. A site selection pilot study was carried out in September 2001 and the Observatory became operational in August 2002.

The site is located in Liverpool Bay and is subject to typical coastal sea processes, with strong tides, occasional large storm surges and waves, freshwater input, stable and unstable stratification, high suspended sediment concentration and biogeochemical interaction. Measurements and monitoring will focus on the impacts of storms, variations in river discharge (especially the Mersey), seasonality and blooms in Liverpool Bay.

A variety of methods will be used to obtain measurements, including:

  1. Moored instruments for in situ time series of currents, temperature and salinity profiles, and surface waves and meteorology. It is hoped that turbidity and chlorophyll measurements will be made at another site as the Observatory progresses;
  2. The Cefas Smartbuoy for surface properties such as nutrients and chlorophyll, starting late 2002;
  3. R.V. Prince Madog to carry out spatial surveys and service moorings;
  4. Instrumented ferries for near surface temperature, salinity, turbidity, chlorophyll and nutrients. The first route will be Liverpool to Douglas, Isle of Man, starting late 2002;
  5. Drifters for surface currents and properties such as temperature and salinity, starting in 2004;
  6. Tide gauges, with sensors for meteorology, waves, temperature and salinity, where appropriate;
  7. Meteorological data from Bidston Observatory and Hilbre Island, HF radar and tide gauge sites;
  8. Shore-based HF radar measuring waves and surface currents out to a range of 50 km, starting in 2003;
  9. Satellite data, with infrared for sea surface temperature and visible for chlorophyll and suspended sediment.

The partners currently involved with the project are listed below:

  • Proudman Oceanographic Laboratory
  • British Oceanographic Data Centre
  • UK Meteorological Office
  • Centre for Environment, Fisheries and Aquaculture Science
  • Environment Agency
  • Liverpool University and Port Erin Marine Laboratory
  • Bangor University School of Ocean Sciences
  • National Oceanography Centre Southampton
  • Department of Agriculture and Rural Development in Northern Ireland

A summary of Coastal Observatory cruises to date on R.V. Prince Madog is given in the table below:

Year No. of cruises Work summary
2001 1 Site selection and pilot study. 95 CTD casts.
2002 4 POL moorings deployed and serviced
Cefas Waverider and SmartBuoy deployed and serviced
103 CTD casts
2003 10 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
341 CTD/LISST casts
2004 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
347 CTD/LISST casts
2005 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
268 CTD/LISST casts
2006 11 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
508 CTD/LISST casts
2007 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
471 CTD/LISST casts
2008 9 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
260 CTD/LISST casts
2009 7 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
213 CTD/LISST casts
2010 8 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
268 CTD/LISST casts
2011 6 POL moorings serviced
Cefas Waverider and SmartBuoy serviced
307 CTD/LISST casts to date, ongoing

Data Activity or Cruise Information


Cruise Name PD33/08
Departure Date 2008-10-22
Arrival Date 2008-10-23
Principal Scientist(s)Matthew R Palmer (Proudman Oceanographic Laboratory)
Ship RV Prince Madog

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Station NameCoastal Observatory Site 12
CategoryOffshore area
Latitude53° 27.08' N
Longitude3° 30.30' W
Water depth below MSL17.0 m

Liverpool Bay Coastal Observatory Site 12

This station is one of 34 stations regularly visited by the Proudman Oceanographic Laboratory (POL) as part of the Liverpool Bay Coastal Observatory. During each site visit, CTD profiles are taken. The station lies within a box of mean water depth 17 m with the following co-ordinates:

Box Corner Latitude Longitude
North-west corner 53.45552° -3.51847°
South-east corner 53.44703° -3.49155°

The position of this station relative to the other POL Coastal Observatory sites can be seen from the figure below.

BODC image

CTD Sampling History

Year Number of Visits Total Casts per year
2011 6 6
2010 5 5
2009 7 8
2008 7 7
2007 9 9
2006 8 8
2005 9 9
2004 9 9
2003 10 10
2002 4 4

The CTD instrument package for these cruises was a Sea-Bird 911plus, with beam transmissometer, fluorometer, LICOR PAR sensor, LISST-25, and oxygen sensor.

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: Coastal Observatory Site 12

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
1013167CTD or STD cast2006-11-02 09:55:0053.44967 N, 3.51033 WRV Prince Madog PD35/06
979191CTD or STD cast2007-02-15 05:31:0053.45067 N, 3.50083 WRV Prince Madog PD02/07
937563CTD or STD cast2007-04-19 13:22:0053.45017 N, 3.50767 WRV Prince Madog PD06/07
942159CTD or STD cast2007-05-17 00:59:0053.45217 N, 3.50583 WRV Prince Madog PD09/07
942854CTD or STD cast2007-06-20 22:04:0053.4505 N, 3.502 WRV Prince Madog PD13/07
943311CTD or STD cast2007-07-27 00:10:0053.45183 N, 3.50133 WRV Prince Madog PD16/07
943716CTD or STD cast2007-08-30 00:02:0053.4515 N, 3.505 WRV Prince Madog PD20/07
945679CTD or STD cast2007-10-03 23:48:0053.45167 N, 3.49833 WRV Prince Madog PD23/07
946529CTD or STD cast2007-11-21 15:26:0053.45117 N, 3.4915 WRV Prince Madog PD27/07
946799CTD or STD cast2008-01-11 00:57:0053.45167 N, 3.50167 WRV Prince Madog PD01/08
946996CTD or STD cast2008-03-13 22:48:0053.44867 N, 3.49733 WRV Prince Madog PD07/08
947293CTD or STD cast2008-04-16 18:34:0053.44783 N, 3.50217 WRV Prince Madog PD09/08
948143CTD or STD cast2008-05-15 05:21:0053.44933 N, 3.50267 WRV Prince Madog PD14/08
949380CTD or STD cast2008-07-31 01:04:0053.44867 N, 3.5065 WRV Prince Madog PD23/08
950159CTD or STD cast2008-12-11 16:22:0053.44883 N, 3.501 WRV Prince Madog PD37/08
950215CTD or STD cast2009-02-05 12:10:0053.447 N, 3.50633 WRV Prince Madog PD02/09B
950553CTD or STD cast2009-02-06 14:31:0053.4475 N, 3.50267 WRV Prince Madog PD02/09B
951593CTD or STD cast2009-04-02 13:36:0053.44717 N, 3.50067 WRV Prince Madog PD12/09
953840CTD or STD cast2009-05-13 16:03:0053.44883 N, 3.50783 WRV Prince Madog PD18/09
1023082CTD or STD cast2009-06-17 17:01:0053.44733 N, 3.5025 WRV Prince Madog PD24/09
1023322CTD or STD cast2009-08-02 21:25:0053.4485 N, 3.50267 WRV Prince Madog PD33/09
1024466CTD or STD cast2009-09-16 15:28:0053.4475 N, 3.50433 WRV Prince Madog PD38/09
1090611CTD or STD cast2010-06-10 10:22:0053.44983 N, 3.5075 WRV Prince Madog PD17/10
1090820CTD or STD cast2010-07-07 17:12:0053.4515 N, 3.504 WRV Prince Madog PD21/10
1112350CTD or STD cast2010-08-12 12:00:0053.45033 N, 3.50433 WRV Prince Madog PD29/10
1114276CTD or STD cast2010-09-29 14:32:0053.4505 N, 3.50183 WRV Prince Madog PD36/10
1149135CTD or STD cast2011-01-13 13:20:0053.45083 N, 3.50183 WRV Prince Madog PD01/11
1150019CTD or STD cast2011-03-17 14:13:0053.449 N, 3.50183 WRV Prince Madog PD07/11
1117170CTD or STD cast2011-04-20 20:10:0053.4505 N, 3.499 WRV Prince Madog PD11/11
1118726CTD or STD cast2011-06-07 03:52:0053.45217 N, 3.51617 WRV Prince Madog PD43/11
1118474CTD or STD cast2011-09-20 10:43:0053.4515 N, 3.50167 WRV Prince Madog PD25/11
1353056Water sample data2011-09-20 10:46:0053.45154 N, 3.50164 WRV Prince Madog PD25/11