Metadata Report for BODC Series Reference Number 1624080

• 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

Originator's quality control comments for PD05_10 COBS moorings

Data supplied to BODC were accompanied by data quality notes from the Originator that detailed observations made when the data were processed and subsequent processing decisions. A summary of these notes have been provided in the tables below.

Site A

Rig#1089

Rig#1090

Site B

Rig#1091

Rig#1092

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

Teledyne RDI Workhorse Sentinel 600 kHz Acoustic Doppler Current Profiler (ADCP)

The Workhorse Sentinel is a self-contained ADCP that can be used either on a mooring or mounted in the hull of a moving vessel. Its 4-beam design provides a redundant data source (in case of a blocked or damaged beam), an independent data quality measure (error velocity) and reduces the variance in data, thereby improving data reliability, quality and accuracy.

Real-time data can be transmitted to shore via a cable link or acoustic modem or they can be stored internally. Sensors for bottom tracking, pressure and directional wave measurements can be added to the instrument and a special casing is available for deeper applications.

Specifications

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

BODC Processing document for Coastal Observatory moored ADCP data

The data arrived at BODC as 117 ASCII format .dat files representing moored ADCP data recorded at the Coastal Observatory sites 1(9), 20 and 21 between 07 August 2002 and 20 September 2011. Following standard BODC procedure the files were reformatted into BODC standard internal format using an internal transfer function. The following table shows how the originator's variables were mapped to the appropriate BODC parameter codes:

The reformatted data were visualised using the in-house EDSERPLO software. Suspect data were marked by adding an appropriate quality control flag, missing data by both setting the data to an appropriate value and setting the quality control flag.

COBS RDI Teledyne 600 kHz ADCP Data Processing

Sampling Strategy

Two mooring sites were maintained for the duration of the Liverpool Bay Coastal Observatory project. Moored instruments present at Site A (also known as Site 1/9) through the entire data collection phase of the observatory. From 05 April 2005 (Cruise PD11_05) moorings were also present at an additional Site B. From April 2005 until December 2009 mooring Site B was located at Coastal Observatory Station 20. The moorings were moved to Station 21 from January 2010, where they remained until the end of the observatory.

Originator's Processing

The raw ADCP data were processed using the standard RDI software bblist which resulted in the creation of two files, the first containing the current velocities separated by bin depth and an auxiliary file containing the variables heading, pitch, roll, temperature and pressure. The variables present in the auxiliary files were only used for quality control purposes with the exception of pressure, which was used to calculate sea surface height taking into account the latitude and the height of the transducer head above the seabed, which was estimated to be 0.7 m. Sea surface height and the current velocity data were then combined into one file.

Before the data were supplied to BODC, some quality control procedures were performed by the Data Originator. First the Originator corrected the latitude values to take into account the difference between magnetic north and true north (magnetic declination). The Originator also corrected the latitude values for compass error caused by localised magnetic fields such as the ADCP frame and battery, using HF radar data recorded by two HF radars located at Abergele and Formby as a reference. Once compass errors for all ADCP series recorded at Site A had been calculated, a mean of all errors was taken. As the ADCP compass error is a random error, the expected mean of all errors is approximately 0°, however the Originator found that the actual mean compass error was approximately 5.3°. All compass errors were therefore modified by 5.3°. The compass error values given in the Originator's data processing documents have taken this adjustment into account.

The bins recorded above the sea surface were then converted to absent data indicators by the Data Originator. If there were any problems with the pressure data recorded by the ADCP, then data from another instrument attached to the same frame was used instead. If no pressure records were available, then backscatter intensity was used to calculate the sea surface. The top three bins have been removed in all series to remove noise in these data caused by side lobe contamination. A more detailed explanation of all of the quality control procedures performed before the data were submitted to BODC can be found in the Originator's ADCP quality control methodology document.

Prior to cruise PD33_08 the data originator had been correcting the mid-water current velocities to account for contamination caused by the recovery line attached to the ADCP lander frame. The mooring design was changed from PD33_08, and this redesign successfully eradicated the beam contamination issues that had affected previous deployments. Therefore, no three-beam correction has been applied to these data. This issue is explained in detail in the originator's ADCP correction report, however as previously stated no three-beam correction was applied to these data.

Finally a visual inspection of the data was carried out to find any obvious errors which had not been corrected by the previous quality control checks.

Project Information

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

Data Activity or Cruise Information

Data Activity

Proudman Oceanographic Laboratory Rig#1092

Deployment and Recovery

The rig was deployed at Coastal Observatory Site B on 17 March 2010 during RV Prince Madog cruise PD05/10 and recovered on 28 April 2010 during RV Prince Madog cruise PD10/10.

Rig Description

This rig is a bottom frame comprising of the following instruments 0.5 m above the seabed: RDI Acoustic Doppler Current Profiler (ADCP); Sea-Bird 16plus; an additional Sea-Bird 16plus providing logging and power for an Aanderaa oxygen optode; and a SonTek ADV (Acoustic Doppler Velocimeter).The frame was fitted with a fizz link, a spooler with 50 m of rope for recovery of the ballast weight and two Benthos releases.

For more information about the instruments please see the cruise report for PD05/10.

Related Data Activity activities are detailed in Appendix 1

Cruise

Complete Cruise Metadata Report is available here

Fixed Station Information

Fixed Station Information

Liverpool Bay Coastal Observatory Site 20

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 collected and since March 2010 (when this became the secondary mooring site for the Coastal Observatory (also known as Site B)) moorings are deployed. The station lies within a box of mean water depth 32.5 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.

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.

Related Fixed Station activities are detailed in Appendix 2

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: POLRIG#1092

Related series for this Data Activity 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.

Appendix 2: Coastal Observatory Site 20

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.