Session 6B.6 Further development of the Tethersonde instrument

Tuesday, 10 June 2008: 11:45 AM
Aula Magna Höger (Aula Magna)
M. J. Hobby, National Centre for Atmospheric Science, Leeds, West Yorkshire, United Kingdom; and S. D. Mobbs and A. M. Blyth

Presentation PDF (738.7 kB)

An instrument (Tethersonde) has been developed that provides wind data at a rate suitable for calculating fluxes by direct eddy correlation. The Tethersonde is designed to be attached to a tethered helium balloon, thus providing high resolution profiles of the atmospheric boundary layer.

Wind speed data are recorded at 10Hz in 3 dimensions in conjunction with the instrument's own motion across 6 degrees of freedom. Post process algorithms can then be used to remove this motion to provide wind vectors in ground based u, v and w coordinate system to a resolution of +/-0.01m/s.

Additionally, pressure, temperature and humidity are recorded at 1Hz to an accuracy of 0.01mb, 1% and 0.1°C respectively. GPS is used to provide UTC timing synchronization.

All components and sensors are integrated within a real time logging system, developed by NCAS at the University of Leeds, and mounted within an aerodynamic fin. The fin has a 3 dimensional sonic anemometer (manufactured by Gill Technology) built in and is designed to always point into the wind.

Data are recorded to a Secure Digital Multimedia card for later retrieval. A radio link is used to transmit data at 1Hz to ground, thus providing an instrument scientist with feedback for positioning the instrument in the sky.

The Tethersonde was used to collect data as part of the AMMA project in North West Africa throughout summer 2006. The instrument was flown at heights of up to 1km and profiles of wind speed, temperature, pressure and humidity were obtained. This highlighted the necessity for a number of improvements to ensure robustness and confidence in the data the instrument provides. Further development has continued throughout 2007, with a more physically robust instrument as a result.

A series of tests are planned for the system during February 2008. The tests will verify the data from the motion sensors independently from the anemometer. Tests in wind tunnels and field comparisons with collocated, calibrated instruments will follow.

The design of the tethersonde and preliminary results from the tests will be presented in this talk.

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