MEASUREMENT DISTORTION IN AIRCRAFT, SPACE-SHUTTLE, AND BALLOON OBSERVATIONS OF ATMOSPHERIC DENSITY AND TEMPERATURE PERTURBATION SPECTRA

Aircraft, space shuttle, and balloon observations are being used to study the density, temperature, and wind structure of the atmosphere. The horizontal and vertical wave number spectra derived from these observations are contaminated by undesired spatial and temporal variations unique to the observational geometries. We use numerical models to quantify this distortion. The results show that distortion is negligible in aircraft and space shuttle measurements of horizontal wave number spectra if the aircraft velocity is approximately 100 m/s or larger and the slant angle of the shuttle reentry path is approximately 0.5-degrees or less. The distortion in balloon measurements of vertical wave number spectra is negligible provided the ascent velocity is approximately 3 m/s or larger and the horizontal wind speed is not more than about 10 times the balloon ascent velocity. This latter condition can be violated during some balloon flights when horizontal winds are strong. In those circumstances the measured spectrum will be larger in magnitude and have a shallower slope than the intrinsic vertical wave number spectrum.