Metadata Report for BODC Series Reference Number 51221

• 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

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 Comments that Runs 54 and 55 produced good data.

BODC Comment that inspection of the time series plot shows that the pressure values have not attained a steady value for data cycles 1 to 5 and 90 to 91; this appears to have affected the other parameters. 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.

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:

1. 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.

2. 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

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:

SeaDataNet Quality Control Flags

The following single character qualifying flags may be associated with one or more individual parameters with a data cycle: