Metadata Report for BODC Series Reference Number 29750

• 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

The wave and swell directions given should be treated with caution.

The wave direction given is the wind direction taken from the meteorological log.

The swell direction given is the swell direction taken from the meteorological log.

Data Access Policy

Public domain 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.

The recommended acknowledgment is

"This study uses data from the data source/organisation/programme, provided by the British Oceanographic Data Centre and funded by the funding body."

Narrative Documents

Data Document for Boyle Station Waverider Buoy

Instrumentation

Datawell waverider buoy transmitting to Warep receiver/recorder on board ship. Paper chart records of 15 minutes duration were made every 3 hours, starting 15 minutes before the hours of 00, 03, 06, 09, 12,15, 18 and 21. From 29 June 1974 onwards, backup recordings were made on analogue magnetic tape using a Geotech F.M. tape recorder. A second waverider buoy on trial for Esso Production Research Co. (EPR Co) was deployed in parallel with the Datawell buoy until January 1975; on occasions when the Datawell buoy was unable to transmit valid data, the EPR Co buoy was used to provide a backup system. Eight different Datawell buoys were used during the programme; serial numbers 6159, 6199, 6298, 6366, 6500, 6501, 6673 and 6679. When the ship temporarily left station during a sea trip, the buoy was often left on station.

Waverider mooring configuration

Calibration

Equipment was checked by Marex engineers at the start of each trip. The waverider buoys were calibrated periodically by Datawell or by the National Maritime Institute, Feltham (see below), and since this resulted in their being within Datawell specification no corrections to the data for instrument errors were necessary.

Data Analysis

The chart records were analysed manually by the Tucker-Draper method (Draper L., The Analysis and Presentation of Wave Data - A Plea for Uniformity. Proc. 10th Coastal Engineering Conf., Tokyo, 1966, Vol. 1, pp 1-11, American Society of Civil Engineers, 1967) to derive values for significant wave height and mean zero upcrossing period. Where available, the analogue tape backup data were used to fill gaps in the chart record data.

Instrument History

Quality Control Procedures

Marex Quality Control

Initial quality control was performed by Marex during the initial preparation and processing of the data. Dubious values identified at this stage were deleted, or replaced by more reliable data from the backup magnetic tape where available. No details of the quality control procedures applied by Marex are available.

MPS Quality Control

Additional quality control was performed by Meteorological and Plotting Services (MPS) Oceanic Limited, Bushey Heath. Records were identified in which:

1. Significant or 3 hour maximum wave height varied by more than 50 per cent between successive records.

2. Significant wave height exceeded 5 metres in summer, 7 metres in winter.

3. Maximum wave height (3 hours) exceeded 10 metres in summer, 14 metres in winter.

4. Mean zero upcrossing wave period exceed 10 seconds in summer, 12 seconds in winter.

5. Unusual variations in mean zero upcrossing wave period were identified by visual examination of the data values.

Values identified by these tests were checked against the corresponding shipborne wave recorder values. Sample checks were also made back to the raw data. Where the analysis was found to be erroneous, replacement values were generated from the original record. If the original record was found to be suspect, the quality control flag has been set to L.

BODC Quality Control

Further quality control was performed by BODC when the data were banked. Records which failed the following tests were examined in detail in the context of the time series of data as a whole:

1. If significant wave height changed by more than 3 metres between successive records, then it must not change by more than 1.5 metres on the following record.

2. If mean zero upcrossing wave period changed by more than 3 seconds between successive records, then it must not change by more than 1.5 seconds on the following record.

3. The ratio of significant wave height recorded by waverider buoy to that recorded by shipborne wave recorder at a given time should be within the range 0.5 to 2.0, and the absolute difference should not exceed 2.5 metres.

4. The ratio of mean zero upcrossing wave period recorded by waverider buoy to that recorded by shipborne wave recorder should be within the range 0.5 to 2.0, and the absolute difference should not exceed 3 seconds.

Two dimensional frequency distributions were plotted of:

1. Significant wave height versus mean zero upcrossing wave period for waverider buoy data and also for shipborne wave recorder data.

2. Significant wave height recorded by the waverider buoy versus that from the shipborne wave recorder.

3. Mean zero upcrossing wave period from the waverider buoy versus that from the shipborne wave recorder.

Extreme values on the periphery of these plots were also examined in detail in the context of the time series of data as a whole. Values identified as dubious by BODC screening procedures are flagged M.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

No Data Activity or Cruise Information held for the Series

Fixed Station Information

Fixed Station Information

Boyle Station Site History

Site

The Boyle Station (50.7° N, 007.5° W) is sited in the Celtic Sea approximately mid-way between Lands End in England and Cape Clear at the southernmost tip of Ireland, in a water depth of 107 metres. It was occupied from 24 May 1974 to 01 June 1977, initially on behalf of the Celtic Sea Oceanographic Study Group (CSOSG) and later (from mid 1975) for the Oceanographic Committee of the United Kingdom Offshore Operators Association (UKOOA). The main aim of the data collection programme was to study the environmental climate for purposes of offshore operations.

Data Collection and Processing

Data collection and processing was performed by Marine Exploration Limited (MAREX), Isle of Wight.

The data collection programme included:

1. Wave data collected at 3 hourly intervals by means of a shipborne wave recorder and a moored waverider buoy.
2. Instrumentally measured wind data collected at hourly intervals.
3. Meteorological synoptic observations made at 3 hourly intervals.
4. Current meter data collected at 10 minute intervals at three different depths.
5. Bathythermograph data collected several times a month (these data were sent to the Hydrographic Department MOD (Navy), Taunton).

The data collection programme was centred about a ship on station for periods of up to 1 month at a time. Gaps of up to a week appear in the data at the end of each on-station period. A total of 38 sea trips was made during the programme, the merchant vessel Skagerak being used throughout.

On Station History

Note: Because the waverider buoy and current meters were deployed just before the ship took station, and were recovered after the ship left station, the period covered by data from these instruments may extend up to 1 day beyond the start and end times of the on station periods given in the above table.

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: Boyle

Related series for this Fixed Station are presented in the table below. Further information can be found by following the appropriate links.

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