A precision kite or balloon-borne mini-sonde for wind and turbulence measurements
✍ Scribed by Ann-Sofi Smedman; Knut Lundin; Hans Bergström; Ulf Högström
- Publisher
- Springer
- Year
- 1991
- Tongue
- English
- Weight
- 656 KB
- Volume
- 56
- Category
- Article
- ISSN
- 0006-8314
No coin nor oath required. For personal study only.
✦ Synopsis
A highly mobile system for accurate measurements of wind speed and horizontal turbulence in the lowest few hundred meters of the atmosphere is presented. It consists of a light-weight sonde (only 50 g. including batteries that permit 12 h of continuous operation) which can be easily lifted by a small kite in winds below 5 m/s and up to at least 25 m/s. In winds below 5 m/s, a small kytoon may be used instead. The signals from the sonde are received by a standard FM-radio equipped with a frequency converter. and data are recorded on ordinary cassette tapes. Field tests against towermounted precision instruments were performed at two sites during neutral and unstable conditions with the sonde suspended 25 m below a small kite. the measuring heights being 11 and 18 m respectively during the two test series. Mean wind speeds are found to be accurate to within 50.2 m/s. Wind speed spectra obtained with the 'flying' sonde can be evaluated up to 0.5 Hz and are found to agree closely with the spectra of the longitudinal component recorded simultaneously by the tower-mounted instrument at the same height. After correction for high frequency loss. which amounted to 5% at this low height (it is expected to decrease rapidly with height), the standard deviation of the wind recorded by the sonde agreed to within 2% with that obtained by the reference instrument. A notable result of the held tests is that there was no sign of degradation of the performance of the sonde in strong turbulence conditions.