Metadata Report for BODC Series Reference Number 37749

• 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

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.

If the Information Provider does not provide a specific attribution statement, or if you are using Information from several Information Providers and multiple attributions are not practical in your product or application, you may consider using the following:

"Contains public sector information licensed under the Open Government Licence v1.0."

Narrative Documents

Type 1 Off-Shore Tide Gauge

This instrument was developed at I.O.S. Wormley. It incorporates a seabed mounted pressure transducer interfaced to a 12 channel Normalair-Garret data logger housed in a 56cm diameter aluminium pressure sphere. The frequency modulated (FM) transducer consists of a diaphragm which when flexed by changing hydrostatic pressure varies the gap of a parallel plate timing capacitor in an LC oscillator circuit. The pressure casing enclosing the transducer circuitry is evacuated so that absolute rather than relative pressure is measured. The frequency output is divided down to about 100Hz and is counted over a period of 890 seconds to average out the unwanted fluctuations due to waves: this sampling period gives 50dB (99.999 p. cent) attenuation of energy from 10 second period waves, but only 0.006dB (0.14 p. cent) attenuation of semi diurnal tidal energy.

The integration period of 890 seconds and the subsequent 10 second scanning and recording sequence are controlled by 900 second pulses from a crystal clock. The reading from each channel is recorded serially in either 3 or 4 decade BCD on 0.25 inch magnetic tape and a parity bit is added during each scan by the digital serializer. A synchronizing signal is recorded on a second track of the tape to assist in translating the magnetic tape during the data processing.

The sphere containing the data logger and interfacing electronics is mounted in a tripod frame made of tubular steel with the pressure transducer mounted on the base of the framework and beneath the sphere. The tripod is supported on a disposable heavy ballast frame consisting of welded girders and the two frames are connected by 3 corrodible magnesium alloy links and a pyrotechnic release mechanism. The recorders are deployed as pop up moorings and released by acoustic release.

Data Processing Notes

Clock gained 3 minutes 31 seconds over 30 days 22 hours 42 minutes 29 seconds; the cycle interval and time values have been corrected.

Instrument Characteristics

Station 2

IOS Data Processing of Off-Shore Pressure Recorder Data

1. Because the pressure is integrated over 890 seconds and then logged, the time value assigned to a data cycle has been chosen as the mid-point between the start and end of each integration period.

2. Instrumental drift and depth have been removed, thus a drift free series is produced with an artificial mean value.

Project Information

No Project Information held for the Series

Data Activity or Cruise Information

Data Activity

Mooring Information

Mooring held 2 meters.

Related Data Activity activities are detailed in Appendix 1

Fixed Station Information

No Fixed Station Information held for the Series

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: C2

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.