Metadata Report for BODC Series Reference Number 34125
No Problem Report Found in the Database
Open Data supplied by Natural Environment Research Council (NERC)
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Teleost Pressure Recorder
This instrument was developed at I.O.S. Bidston. Each recorder consists of a Bell and Howell strain gauge or a Digiquartz pressure transducer. The strain gauge sensor uses a Bell and Howell type 4-306 transducer and operates as a phase shift oscillator whose frequency is controlled by the ratio of output to input voltage of the transducer Wheatstone bridge network. The quartz crystal pressure sensor consists of a convoluted bellows linked to a 40kHz quartz crystal resonator coupled by piezoelectric action to an electronic resonator.
The pressure and temperature recorder consists of an Aanderaa current meter type logger modified to accept input from a pressure sensor containing a Bell and Howell strain gauge or a Digiquartz pressure transducer and a platinum resistance thermometer.
The pressure and temperature transducers are mounted in the same heat sink for compatible data. The pressure sensors are mounted in a protective frame of dimensions 1.75m by 1.14m by 0.66m, attached to a ballast plate or frame. Teleost recorders are deployed as pop-up moorings and released from their ballast frames by firing a pyrotechnic release by acoustic command.
IOS Calibration and Data Processing of Off-Shore Tide Gauge Data
Calibration of pressure/frequency sensors and thermistors are carried out using the facilities and staff at I.O.S. Bidston with the exception of pre 1975 pressure/frequency sensors, which were calibrated in the pressure chamber at I.O.S. Wormley.
The data are copied from the logger magnetic tape to 9 track magnetic tape and disk. The data are either listed or plotted as an initial check. A program is then used to check the data from the temperature sensor channels, calculate and plot the temperature values and store them (if temperature sensor channels are available).
A second program performs a similar function for the pressure sensor channel, using the pressure frequency coefficient to convert each pressure frequency to the frequency at the reference temperature and calculating the pressures using the pressure frequency calibration. The data values, generally at 15 minute intervals, but occasionally at 10 minute intervals, of pressure are then plotted and stored. If waterhead is required, it may be computed by subtracting atmospheric pressure and applying the hydrostatic relation:-
H = P / ( d * g )
H = waterhead (cm)
P = pressure (0.01 mb)
d = density (kg/m3)
g = gravitational acceleration (m/s2)
Station Lavernock Point (Severn Estuary) Data Processing Notes
Clock gained 20 seconds over 69 days 6.25 hours; the cycle interval and time values have been corrected.
Instrument Characteristics and Calibration Factors
|Teleost Pressure Recorder||Sensor DIG |
Serial number 281
|Original sampling interval||15 minutes|
|Temperature coefficient||-0.625 Hz/°C|
|Pressure sensitivity at 9.867°C||0.1247 Hz/mb|
To convert pressure to elevation the following values should be used:
|Density (from CTD casts)||1022.0 kg/m3|
|Gravitational acceleration constant||9.812 m/s2|
A Danforth anchor with 18m of chain was deployed connected to the recorder box so that the rig was parallel to the ebb and flood tide. Density calculated from measured temperature and a salinity of 29 parts per thousand.
No Project Information held for the Series
No Data Activity or Cruise Information held for the Series
No Fixed Station Information held for the Series
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
|<||Below detection limit|
|>||In excess of quoted value|
|A||Taxonomic flag for affinis (aff.)|
|B||Beginning of CTD Down/Up Cast|
|C||Taxonomic flag for confer (cf.)|
|E||End of CTD Down/Up Cast|
|G||Non-taxonomic biological characteristic uncertainty|
|I||Taxonomic flag for single species (sp.)|
|K||Improbable value - unknown quality control source|
|L||Improbable value - originator's quality control|
|M||Improbable value - BODC quality control|
|O||Improbable value - user quality control|
|0||no quality control|
|2||probably good value|
|3||probably bad value|
|6||value below detection|
|7||value in excess|
|A||value phenomenon uncertain|
|Q||value below limit of quantification|