Metadata Report for BODC Series Reference Number 953760

• Metadata Summary

• Problem Reports

• Data Access Policy

• Narrative Documents

• Project Information

• Data Activity or Cruise Information

• Fixed Station Information

• BODC Quality Flags

• SeaDataNet Quality Flags

Metadata Summary

Problem Reports

No Problem Report Found in the Database

Prince Madog Cruise PD18_09 CTD 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.

Data Access Policy

Open Data supplied by Natural Environment Research Council (NERC)

You must always use the following attribution statement to acknowledge the source of the information: "Contains data supplied by Natural Environment Research Council."

Narrative Documents

Sea-Bird Dissolved Oxygen Sensor SBE 43 and SBE 43F

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

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

Specifications

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

Prince Madog Cruise PD18_09 CTD Instrumentation

The CTD unit was a Sea-Bird Electronics 911plus system (SN 09P23655-0620), 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.

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

Specifications for the SBE 9 plus underwater unit are listed below:

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.

Specifications

The table below presents the specifications for the different channels.

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)

SeaTech Transmissometer

Introduction

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

Specifications

• 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)

Notes

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

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

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

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.

Specifications

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

Prince Madog Cruise PD18_09 CTD Processing

Originator's Data Processing

• Sampling Strategy

  A total of 36 CTD profiles were performed during the cruise throughout Liverpool Bay. 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 7.18d. 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 2 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. LOOP EDIT was run to compensate for the effects of 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 Voltage, SBE 43	Un-adjusted volts	Instrument output (voltage) by in-situ oxygen microelectrode	OXYVLTN1	Un-adjusted volts	Not banked by BODC. Used to calculate DOXYSU01
  Oxygen, SBE 43	ml l-1	Dissolved oxygen concentration from SBE 43 sensor	DOXYSU01	µmol l-1	ml l-1 * 44.66
  Salinity	-	Practical salinity of the water body by CTD	PSALCU01	-	Not banked by BODC. Data are un-calibrated. Used as source data for PSALCC01
  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
  -	-	Salinity	PSALCC01	-	Generated by BODC from calibration of PSALCU01
  -	-	Temperature	TEMPCC01	°C	Generated by BODC from calibration of TEMPCU01
  -	-	Oxygen saturation	OXYSSU01	%	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 where necessary, generate interpolated values to fill in gaps in the increment sequence. Finally, the CTD downcasts were banked.

Field Calibrations

• Salinity

  34 independent salinity samples obtained from the CTD rosette were used to calibrate the CTD; one data point was identified as an outlier and was removed from the analysis and no salinity sample was collected during cast 28. The offset between CTD salinity and independent salinity (Autosal salinity - CTD salinity) was found, using regression analysis, not be be significantly related to independent salinity at a 95% confidence level. A calibration equation was derived from the mean offset as follows, based on 34 observations: calibrated salinity = CTD salinity - 0.00732. The RMS error for this dataset is 0.0067823 and the standard deviation is 0.00691.

• Temperature

  160 independent temperature values were compared to pressure and CTD temperature; 3 data points were identified as outliers and were removed from the analysis. The temperature offset (SBE 35 temperature - CTD temperature) was found, using regression analysis, not to be significantly related to SBE 35 temperature at a 95% confidence level. The mean offset is -0.000823 °C and the standard deviation for this dataset is 0.003858 °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 (4.32723 volts); Y1 is the current blocked path voltage (0.00 volts). For this cruise, M and B were calculated to be 21.5426 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])

  where

  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)

• 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:

  • V_T = measured transmission output V
  • V_Toff = transmission output offset = 0.007 V
  • V_TO = clear water transmission output = 2.828 V
  • cal = total volume concentration calibration constant = 630
  • V_S = measured scattering output V
  • V_Soff = scattering output offset = 0.004 V
  • V_SO = 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
  2008-12-09	PD37_08	2.59341	0.15995
  2009-02-01	PD02_09A/B	2.59829	0.15751
  2009-03-02	PD06_09	2.57631	0.16484
  2009-03-31	PD12_09	2.52381	0.17216
  2009-05-11	PD18_09	2.55433	0.18315

• 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.

Weblink: http://www.oceans2025.org/

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.

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

Weblink: http://www.oceans2025.org/

References:

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:

Data Activity or Cruise Information

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Liverpool Bay Coastal Observatory Site 21

This station is one of 34 stations regularly visited by the Proudman Oceanographic Laboratory (POL) as part of the Liverpool Bay Coastal Observatory. The main activity at this site are CTD profiles (since August 2002) which are taken during each site visit. This station was also the secondary mooring site (also referred to as Site B) for the Coastal Observatory project between April 2005 and March 2010. After March 2010 the moorings were moved to site 20. The station lies within a box of mean water depth 24 m with the following co-ordinates:

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

Mooring Deployment History

2010

2009

2008

2007

2006

2005

CTD Sampling History

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

Key

ADCP = Acoustic Doppler Current Profiler
BD = Bacterial degradation experiment
CT = Conductivity and temperature logger
CTD = Conductivity, temperature, depth sensor
FL = Fluorometer
OBS = Optical Backscatter Turbidity meter
Telemetry ADCP = ADCP sending data back to shore in real-time
WMS = Automatic water sampler

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:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:

Appendix 1: Coastal Observatory Site 21

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.