Metadata Report for BODC Series Reference Number 51165
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
Data Description |
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Data Identifiers |
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Time Co-ordinates(UT) |
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Spatial Co-ordinates | |||||||||||||||||||||||||||||||||||||||||||||||||
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Parameters |
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Problem Reports
No Problem Report Found in the Database
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 Processing Notes
Data Originator Comment that for Runs 12 and 13 there were some problems with temperature and specific humidity and a few minutes of wind problems.
Average height of instrument package | Run 12 200m Run 13 260m. |
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Axis rotation to force vertical velocity to zero | Run 12 0.269 radians Run 13 0.290 radians |
BODC Comment that inspection of the time series plot shows that the pressure values have not attained a steady value for data cycle 1; this appears to have affected the other parameters. Also data cycles 49 to 51 are noisy for for vertical and horizontal wind speed and temperature; data cycles 91 to 92 have a spike on the horizontal and vertical wind speed channels. These data cycles should be treated with caution.
JASIN Tethered Balloon Data collected by HMS Hecla
Introduction
H M S Hecla was located at 60° 15' N, 10° 3' W between 16 and 28 July (Phase 1) and 22 August and 05 September 1978 (Phase 2) . A tethered balloon was flown from the aft of the ship during this period. Turbulence probes from the UK Meteorological Office Porton Group were instrumented with a miniature cup anemometer for wind speed, dry and wet bulb platinum sensors, a hot wire inclinometer and an aneroid capsule. These were mounted on a vane clamped to a captive balloon cable and an electronics box mounted beneath telemetered FM data of wind speed, wind inclination, dry and wet bulb temperatures and pressure to be recorded on an analogue tape recorder. The tapes were then played through filters and digitised at 10Hz. Raw data were then transferred to the Meteorological Office computer at Bracknell and spectra and fluxes were calculated.
Instrumentation
The following sensors were included in the package.
Sensor | Parameter Measured | Accuracy | Sampling Frequency |
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Cup anemometer | Mean wind speed | 2 per cent | Continuous |
Magnetic compass | Horizontal wind direction | 3 degrees | 20Hz |
Dual V hot wire inclinometer | Inclination of wind to horizontal | 1 degree | Continuous |
Platinum resistance thermometer | Dry and wet bulb temperatures | 0.2 °C | Continuous |
Aneroid capsule | Atmospheric pressure | - | - |
Continuous data recorded continuously in analogue form but digitized at 10Hz.
Calibrations
Sensors were calibrated in the laboratory before and after the experiment. Field calibrations were limited to checks of the sensitivities of the electronic signal processing circuits, by substitution of dummy sensors.
Before averaging checks on the time derivatives of horizontal and vertical windspeeds and temperatures were performed to remove spikes (mainly a problem with wind speeds). Data were then averaged over 102.4 seconds. The time value associated with each data cycle is the mid-point of each 102.4 second averaging period. Wind speeds have not been corrected for ship motion. The standard deviation of the wind speeds is seriously affected by the action of waves on the ship.
To calculate the specta and co-spectra the mean vertical velocity was forced to zero by applying an axis rotation. The rotation has not been performed, but the rotation angles have been supplied for each series. Phase 1 of JASIN was used mainly as a proving phase and measurements were severely limited by problems with the balloon system and instrumentation. The hydraulic gear which automatically pulled in and paid out the balloon cable to compensate for ship motion, designed for (and used successfully in) the GARP Atlantic Tropical Experiment, was not able to cope with the heavy seas encountered in JASIN.
During Phase 2 the balloon was raised on 22 August 1978 (after strong winds had abated sufficiently) and remained aloft until 05 September 1978. In all some 160 hours of data were recorded during Phase 2 made up of about 100 runs when the probe was at a constant height between 50m and 450m. Measurements were made by day and by night using one turbulence probe.
Data from 36 runs, totalling approximately 65 hours, are held by BODC.
Note: The first specific humidity data cycle (and associated standard deviation) on each series is probably not a valid data value.
Reference
S. Nicholls et. al. 1983
The structure of the turbulent atmospheric boundary layer. Phil. Trans. Roy. Soc. London A Volume 308 pp 291 - 309.
Project Information
Joint Air Sea Interaction Experiment (JASIN)
The JASIN Project was designed to study the interaction of the atmospheric and oceanic boundary layers with the larger scale motions of the sea and the air.
The primary aims may be summarized as follows:
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To observe and distinguish between the physical processes causing mixing in the atmospheric and oceanic boundary layers and relate them to the mean properties of the layers.
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To examine and quantify aspects of the momentum and heat budgets in the atmospheric and oceanic boundary layers and fluxes across and between them.
The multiplicity of processes to be sampled necessitated a large experiment and JASIN involved 14 ships and 3 aircraft with more than 50 teams of investigators from 9 countries. Altogether 35 mooring systems were deployed.
The experiment lasted for 2 months from mid-July to mid-September 1978 and comprised 2 intensive measuring periods preceded by a preparatory test period. The project took place in the north Rockall Trough, an area of deep water (1000m - 2000m) several hundred kilometres off the west coast of Scotland.
Data Activity or Cruise Information
Cruise
Cruise Name | HECLA_JASIN78 |
Departure Date | 1978-07-14 |
Arrival Date | 1978-09-05 |
Principal Scientist(s) | Unknown (Unknown) |
Ship | HMS Hecla |
Complete Cruise Metadata Report is available here
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:
Flag | Description |
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Blank | Unqualified |
< | 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.) |
D | Thermometric depth |
E | End of CTD Down/Up Cast |
G | Non-taxonomic biological characteristic uncertainty |
H | Extrapolated value |
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 |
N | Null value |
O | Improbable value - user quality control |
P | Trace/calm |
Q | Indeterminate |
R | Replacement value |
S | Estimated value |
T | Interpolated value |
U | Uncalibrated |
W | Control value |
X | Excessive difference |
SeaDataNet Quality Control Flags
The following single character qualifying flags may be associated with one or more individual parameters with a data cycle:
Flag | Description |
---|---|
0 | no quality control |
1 | good value |
2 | probably good value |
3 | probably bad value |
4 | bad value |
5 | changed value |
6 | value below detection |
7 | value in excess |
8 | interpolated value |
9 | missing value |
A | value phenomenon uncertain |
B | nominal value |
Q | value below limit of quantification |