Measurements of Wind Fluctuations by a Vane Mounted on the Captive Balloon Cable

摘要

In order to measure the wind fluctuations in the layer the height of which is 500 m above the ground, a bi-directional vane mounted on a captive ballon cable has been developed. Vertical and lateral wind fluctuations are detected by the bi-vane and magnetic compass. Signals of these quantities are transmitted to the surface and recorded. Response characteristics have been investi-gated in a wind tunnel. The distance constant of vane, U/ωnξ(U is wind speed, ωn is frequency of the natural oscillation and ξ is the damping ratio) has been measured and found to be ap-proximately 1.6 m. In preliminary observations, spectra of the vertical and lateral wind fluctua-tions have been measured for the frequency ranges from 0.05 to 1.0 Hz. Intensities of the fluctuations and the maximum frequencies np of the logarithmic vertical spectra have been measured in the layer below 500 m.