Effects of Sound Speed Fluctuations on Sonic Anemometer Measurements.

摘要

The effects of sound speed fluctuations on various measurements made with sonic anemometers are derived. Corrections due to temperature-generated sound speed fluctuations on measured statistics are estimated from the 1968 AFCRL Kansas data for different stability conditions. For most statistics, the corrections were not large: the maxima were -3.5% to the measured horizontal velocity, vertical velocity covariance (u-bar, w-bar, proportional to the Reynolds stress) and -8.2% to the measured horizontal velocity, temperature covariance (u-bar theta-bar, proportional to the horizontal heat flux) for unstable conditions. It is also shown that the measured cospectrum of u-bar w-bar, is contaminated by the cospectrum of w-bar theta; in the inertial subrange of frequencies, the measured u-bar w-bar cospectra for the AFCRL data for unstable conditions were calculated to be high by 5-11%. (Author)