Vertical wavenumber spectra of wind and temperature from high-resolution balloon soundings over Illinois

We spectrally analyzed high-resolution balloon measurements of vertical profiles of temperature and horizontal wind in the troposphere and lower stratosphere over very flat terrain in Illinois. This paper is principally concerned with spectra in the power law range at vertical wavenumbers m greater than or similar to 10(-3) cycle/m. The logarithmic spectral slopes and amplitudes are found to have only insignificant dependencies on meteorological parameters, including time of day, season, wind speed and direction, vertical shear, etc., except that between the troposphere and stratosphere the spectral amplitude scales as (N-2)(q) with q similar to 0.3, where N is the buoyancy frequency. The mean slopes are approximate to -3 in the stratosphere and approximate to -2.6 in the troposphere. On the average the individual spectra with larger amplitudes have less negative spectral slopes. The wide variation of spectral slopes (sigma approximate to 0.5) and amplitudes and the weak dependence on N-2 are quite inconsistent with the predictions of theories of saturated spectra. Further, the wind spectra in the troposphere and stratosphere are correlated, which suggests some unsaturated propagation between the regions. The ratio of kinetic to potential energy spectra is constant versus m, consistent with the linear gravity wave polarization relations. The magnitude of the model ratio can be brought into agreement with the observed ratio by assuming a model intrinsic frequency spectrum varying as omega(-p) with p similar to 5/3 to 2 plus an enhancement of energy near the inertial frequency.