Metadata Report for BODC Series Reference Number 747334

• 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

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

Aanderaa Oxygen Optodes models 3835, 4130, 4175, 3830, 3930 and 3975

The Aanderaa Oxygen Optode is based on the ability of selected substances to act as dynamic fluorescence quenchers. The fluorescent indicator is a special platinum porphyrin complex embedded in a gas permeable foil that is exposed to the surrounding water.

A black optical isolation coating protects the complex from sunlight and fluorescent particles in the water. This sensing foil is attached to a window providing optical access for the measuring system from inside a watertight titanium housing.

The foil is excited by modulated blue light, and the phase of a returned red light is measured. By linearizing and temperature compensating, with an incorporated temperature sensor, the absolute O₂ concentration can be determined. According to the manufacturer, the lifetime-based luminescence quenching principle offers the following advantages over electro-chemical sensors:

• Not stirring sensitive (it consumes no oxygen)
• Less affected by fouling
• Measures absolute oxygen concentrations without repeated calibrations
• Better long-term stability
• Less affected by pressure
• Pressure behaviour is predictable
• Faster response time

The 3835, 4130 and 4175 models are designed to operate down to 300 m, while there are two versions of the 3830, 3930 and 3975 models, designed to operate down to 2000 m and 6000 m, respectively. The sensors fit directly on to the top end-plate of Recording Current Meter RCM 9, and other Aanderaa instruments. Sensor specifications may be viewed via the following links: Aanderaa Oxygen Optodes 3835/4130/4175 and Aanderaa Oxygen Optodes 3830/3930/3975.

Cefas SmartBuoy data processing

This document outlines the procedures in place at Cefas in August 2005 for processing and quality assuring SmartBuoy data.

Raw data files are processed and the data move through 4 levels, starting with raw data at level 0 through to level 3, where data are fully quality-assured and expressed in appropriate units. The application of the procedures at each level result in data deemed fit to progress to the next level.

Cefas Quality Assurance (QA) Protocols

At Level 0, raw binary data files from the loggers are transferred to the network.

Automated checks - Level 1

Level 1 involves applying automated quality assurance procedures to the data. These include the following steps:

• Burst data are loaded into memory for processing.
• Calibration data for all instruments and sensors used on the deployment are retrieved from the SmartBuoy database. These may be manufacturers' sensor calibrations or the most current laboratory calibrations. Instruments are returned to the manufacturer and re-calibrated at regular intervals.
• mV are converted to volts, where necessary.
• LiCor signals are converted from Volts to PAR irradiance in µE m^-2 s^-1.
• Salinity is derived from C and T using UNESCO 88 (PSS78) formula.
• Burst data maximum and minimum ranges are checked and flagged if they fail the checks.
• Burst means, result count, and result standard deviation are calculated from non-flagged burst data.
• If there are data from two PAR sensors at different depths, Kd (m^-1) is calculated for burst mean data only as LN(PAR1m/PAR2m).
• Burst mean data maximum, minimum and rate of change checks are carried out and flags applied to any failures.
• Time stamped burst and burst mean data with default units are stored on SmartBuoy database.

The data are now at QA status = 1.

Manual checks - Level 2

Level 1 burst mean data are now ready for manual QA procedures in order to progress to Level 2. Deployment notes are consulted for any comments on sensor performance or malfunction and post-deployment photographs of sensors, if available, are examined.

Cefas use a data visualisation tool to examine the SmartBuoy data.

• A comparison is made between the end of one deployment with beginning of the next to identify possible drift and/or biofouling of OBS, Fluorometer, Salinity, PAR, and oxygen sensors.
• Battery voltages are checked for sudden jumps and, if present, other sensors are examined for similar jumps to determine whether there is a problem with the sensor or if the buoy was disturbed.
• Reference voltages on the FSI CT module are checked.
• The standard deviation of OBS is examined. A steady increase in standard deviation is a good indication of the onset of biofouling. It is also used as a rough indicator for fluorometers during summer, except during spring, when there are large fluctuations in chlorophyll.
• Li-Cor is examined for fouling, which could be indicated by a steady drop in daily maximum or a steady increase in standard deviation. If above-water Li-Cor data are available, they are used for comparison.
• Pressure is examined for sudden decreases, indicating when the buoy was taken out of the water.
• Roll and pitch are examined for any anomalies. It is expected that the spring/neap cycle will be present in the buoy tilt signal.
• Where possible, comparison is made between burst mean data from sensors measuring the same variable. This is in order to determine whether there is a systematic offset (drift) or sensor fault and whether biofouling is present.
• Comparison is made between burst mean sensor outputs from different variables as this can be helpful in determining the onset of biofouling. Any data that fail the checks are flagged with flags specific to the check that was failed.

Calibrations - Level 3

The combined information from Level 2 is used to determine the periods during which the data series are considered suspect. The data have now reached QA status = 2 and can progress to Level 3, where they will be fully calibrated with field-derived sample data.

• For salinity an offset is calculated as the difference between result output from logger and the result from a discrete sample collected at the same time.
• Calibration from regression analysis of field samples and logger output is applied to derive new parameters, e.g. chlorophyll calculated from fluorescence, suspended load calculated from OBS.
• Chlorophyll calibrations are determined from GF/F filtered water samples, which are extracted in acetone and measured for fluorescence using a Turner Designs Fluorometer.
• Suspended matter calibrations are determined from a known volume of water sample filtered through pre-weighed 0.4 µm Cyclopore filters. The filters are dried and reweighed to determine the weight of material per unit volume.
• Salinity is calibrated using water samples that have been analysed with a Guildline Autosal salinometer.
• Water samples from the Aqua Monitor are analysed for nutrients by colorimetric analysis of 0.4 µm Cyclopore-filtered samples.

The data have now reached QA status = 3 as time stamped, field calibrated burst mean data with parameter codes and units stored on SmartBuoy database with associated uncertainty or 95% confidence limits as appropriate. All SmartBuoy data banked at BODC have passed full Cefas QA procedures. Data that fail the Cefas QA checks are not submitted for banking.

SmartBuoy data processing by BODC

The following outlines the procedures that take place at BODC for banking Cefas SmartBuoy data.

BODC receives SmartBuoy data from Cefas after all quality checks have been passed and all possible calibrations applied. The data files are submitted as separate MS Excel spreadsheets for each parameter, i.e. there are separate files for temperature and salinity from the same instrument. An exact copy of the data is archived for safekeeping upon arrival.

Once the submitted data files are safely archived, the data undergo standard reformatting and banking procedures:

• The data files are reformatted using an in-house program into a common format, which is a NetCDF subset.
• Data files arising from the same instrument are combined into a single file.
• Standard parameter codes are assigned that accurately describe the data.
• Unit conversions are applied, if necessary, so that units are standardised. Oxygen concentration supplied by the originator in units of mg l^-1 is converted to µmol l^-1 by multiplying by 31.25.
• The data are screened visually and any spikes or instrument malfunctions can be clearly labelled with quality control flags.
• Comprehensive documentation is prepared describing the collection, processing and quality of each data series.
• Detailed metadata and documents are loaded to the database and linked to each series so that the information is readily available to future users.

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

Smartbuoy deployment LB_038/POLRIG985

Deployment and Recovery

This rig was deployed as part of the Liverpool Bay Coastal Observatory during R.V. Prince Madog cruise PD37_06. The weather was stormy throughout the cruise (force 7 - 9), however, the moorings work was successfully achieved. Recovery of the rig took place during R.V. Prince Madog cruise PD02_07.

Rig Description

This rig is a single line mooring, comprising a surface CEFAS SmartBuoy and POL instrumentation suspended beneath. The single point mooring was mainly composed of 0.5 inch long link chain and marked at the surface by a 1.8 m diameter toroid (the CEFAS SmartBuoy) and anchored by a half tonne clump of scrap chain. The CEFAS Smartbuoy contains a suite of instruments mounted just below the surface.

The table below details the CEFAS instrumentation

The table below details the POL instrumentation

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: LB1_38/985

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.