Measuring Atmospheric Turbulence with Airborne Hot-Film Anemometers

Abstract

Extensive flight tests during GATE showed hot-film anemometry to be a useful tool for the airborne measurement of atmospheric turbulence in clear air and in subcloud rain, but not within clouds. Root-mean-square noise values lower than 0.08 ms?1 for velocity and 0.03°C for temperature were obtained over the scale range of 50 m to 4 cm at altitudes from 16 to 2000 m. Spectra of U?, W? and ? were obtained over the same range with roughly 1 dB accuracy. Dissipation rates could be determined to within ±30%. Cross-component contamination was too large to permit reliable cross spectra to be obtained. It is suggested that an upgraded system could significantly reduce such contamination and improve the overall accuracy and signal-to-noise ratio.