Metadata Report for BODC Series Reference Number 1623408

• 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 PD37_06 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.

Rig#985

Rig#986

Rig#988

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. This included removing surface null bins.

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.

Analysis of the Coastal Observatory ADCP data found that some of the midwater beams had been contaminated, with the Originator suspecting that the cause was the contamination of individual acoustic beams by the recovery line attached to the ADCP lander frame. As the contamination only affected individual acoustic beams, it was possible to estimate the horizontal component of the contaminated beam using the vertical components of the two perpendicular beams and the unaffected horizontal component. A full description of how this procedure was carried out can be found in the Originator's ADCP correction report

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

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

Data Activity

Proudman Oceanographic Laboratory Rig#986

Deployment and Recovery

This rig was deployed as part of the Liverpool Bay Coastal Observatory during R.V. Prince Madog cruise PD37_06. All of the major moorings objectives were accomplished during this cruise. Recovery of the rig took place during R.V. Prince Madog cruise PD02_07.

Rig Description

This rig was a bottom frame comprising of the following instruments 0.5 m above the seabed; Waves Acoustic Doppler Current Profiler (ADCP), a SonTek ADV Logger and a SeaBird 16plus. The frame was fitted with two Benthos releases s/n 71922 (Rx 11.5 kHz, Tx 12.0 kHz, release A) and s/n 72858 (Rx 14.5 kHz, Tx 12.0 kHz, release A) both fitted with a fizz link and a spooler with 150m of rope for recovery of the ballast weight.

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 Mooring Site A (COA/Site 1/Site 9)

This station is the main mooring site for the Proudman Oceanographic Laboratory (POL) Liverpool Bay Coastal Observatory and was first occupied in 2002. It is also known both as Coastal Observatory Site 1 and Site 9. POL perform two main types of activities at this station: they deploy moorings; and in addition, they take CTD profiles during each site visit. The station lies within a box of mean water depth 22.5 m with the following coordinates:

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

Mooring Deployment History

2011

2010

2009

2008

2007

2006

2005

2004

2003

2002

2001

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

AC-S = Absorption and attenuation spectrophotometer
ADCP = Acoustic Doppler Current Profiler
ADV = Acoustic Doppler Velocimeter
BD = Bacterial degradation experiment
BPR = Bottom Pressure Recorder
CT = Conductivity and temperature logger
CTD = Conductivity, temperature, depth sensor
FL = Fluorometer
NAS = in-situ nutrient analyser
OBS = Optical Backscatter Turbidity meter
OXY = Oxygen sensor
PAR = PAR sensor
T = Temperature logger
TR = Transmissometer
WMS = Automatic water sampler

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: POLRIG986

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: COA

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.