Metadata Report for BODC Series Reference Number 34186
No Problem Report Found in the Database
Open Data supplied by Natural Environment Research Council (NERC)
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Aanderaa Pressure Recorder Type TG-2A and WLR-5
Pressure recorder TG-2A (serial number 64) was used until the end of 1979. It was then returned to Aanderaa Instruments Limited who carried out modifications changing it to the specification of an Aanderaa WLR-5. Hence from 1980 onwards the instrument is known as Aanderaa WLR-5 (serial number 500).
The Aanderaa recorder uses a Digiquartz type 2-300a quartz crystal pressure transducer. The pressure sensor consists of a convoluted bellows linked to a 40kHz quartz crystal resonator coupled by piezoelectric action to an electronic resonator. The sensor pack is mounted in a low profile steel tripod frame 0.76m by 1.183m in size with the sensor level approximately 0.48m above the frame base. Data are recorded on to 0.25 inch magnetic tape on an Aanderaa data logger in the same case. A quartz crystal clock is used for controlling the sampling interval.
The data are recorded as 10 bit binary words in serial form with the frequency count from the sensor stored as the most and least significant counts. There is no temperature sensor. The tide gauge is usually deployed using a U-shaped mooring (i.e. buoy or pellet float to wire rope to tide gauge to ground line to anchor to wire rope to buoy), but W-shaped moorings are used in conjunction with either current meters or thermistor chains. A W-shaped mooring comprises pellet float to pellet line to sub-surface buoy to current meter or thermistor line to anchor weight to ground line to tide gauge to ground line to anchor weight to wire rope to surface buoy.
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 E (North Sea) Data Processing Notes
Clock lost 2 seconds over 54 days, 4.5 hours; the cycle interval and time values have been corrected.
Instrument Characteristics and Calibration Factors
Aanderaa WLR-5 , sensor DIG, serial number 500
|Original sampling interval||15 minutes|
IOS North Sea Experiment 1981
An experiment was carried out by I.O.S. Bidston in the North Sea during May and June 1981. The scientific objectives were:
- To investigate the slope of the mean sea level surface between Leith and Immingham.
- To study the tidal energy budget in a shallow coastal region.
- To measure currents around a sandbank to test theories of spring neap changes in the mean currents.
24 rigs containing recording current meters, thermistor chains or pressure recorders were deployed for 40 days at 15 stations. Data from nearby coastal tide gauges were also used. The density field was measured during both the deployment and recovery legs by continuous monitoring of sea surface temperature and conductivity and by recording CTD profiles.
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|