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Abstract. Different methods have been proposed to derive the energy dissipation rate and eddy diffusion coefficients from ST radar measurements. However, their validity is still questionable because they implicitly assume that the Prandtl number is always equal to one, an assumption which is not verified. An experimental approach to this question, using balloon-borne experiment results, is proposed in this paper in order to test the validity/invalidity of the methods generally used. In situ observations show that the potential temperature gradient is more efficiently (and probably more rapidly) eroded by the turbulent activity than the wind shear.

We present simultaneous in situ measurements of a long‐period inertio‐gravity wave and of clear air turbulence events associated with wave propagation. The energy budget of the wave‐turbulence interaction shows that a wave of long period and of short vertical wavelength may propagate upward over several wavelengths close to the shear instability conditions. This result allows one to interpret the spatiotemporal structure of CAT layers as reported in the literature and in particular their horizontal and vertical extent, their thickness, and their persistence.

A Garrett‐Munk‐type spectrum, describing in the frequency–wave number space the energy per unit mass distribution of the atmospheric buoyancy wave field, is derived from experimental spectra of the field variables, within the following constraints: (1) the spectral modeling must refer only to kz spectra, in order to minimize the spectral contributions of the possibly coexisting quasi‐two‐dimensional turbulence and; (2) the resulting model must correspond to a saturated wave field in its high wave number limit. A spectral dependence on intrinsic frequencies is estimated from the ratios of experimental temperature and vertical velocity kz spectra, obtained by balloon‐borne instrumentation. These results and previously published horizontal velocity kz spectra allow determination of the model spectrum parameters, which differ substantially from those proposed by VanZandt (1982). This resulting model spectrum is characterized by a nearly universal high wave number limit (with a −3 spectral slope) and a total energy that varies, mainly with altitude. Two typical atmospheric conditions, characterized by high or low vertical velocity variances, are, however, much better represented using two slightly different parameter sets. Then, the model spectra account for most experimental mesoscale range kz, kH, and frequency spectra. As a tentative interpretation, it is suggested that these two conditions are associated with the presence or absence of a turbulent buoyancy subrange, while, in both cases, the energy levels within the saturated subrange imply strongly interacting wave fields.

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