[1] In order to examine internal gravity wave characteristics we have analyzed small-scale fluctuations of normalized temperature in the Earth's stratosphere using radio occultation data. An analysis to identify the observed fluctuations as wave-induced, assuming gravity wave shear saturation, is proposed. This technique is based upon a comparison of the experimental and theoretical values of the relative amplitude threshold which is defined as the wave amplitude required for shear instability. The theoretical amplitude threshold, assuming a minimum Richardson number of 1/4, is a function of f/w, where f and w are inertial and intrinsic frequencies, correspondingly. The theoretical threshold values are confined from zero to unity. In the case when this criterion is satisfied for its experimental counterpart and the analyzed fluctuations are positively identified as wave-induced, then the intrinsic frequency of the monochromatic gravity wave can be determined from only a single vertical temperature (or density) profile measurement. The results of the determination of the intrinsic frequency and other characteristics of internal gravity waves are presented and discussed.Citation: Gubenko, V. N., A. G. Pavelyev, and V. E. Andreev (2008), Determination of the intrinsic frequency and other wave parameters from a single vertical temperature or density profile measurement,
Abstract.A new method for the reconstruction of internal gravity wave (IGW) parameters from a single vertical temperature profile measurement in the Earth's atmosphere has been developed. This method does not require any additional information not contained in the profile and may be used for the analysis of profiles measured by various techniques. The criterion for the IGW identification has been formulated and argued. In the case when this criterion is satisfied, then analyzed temperature fluctuations can be considered as wave-induced. The method is based on the analysis of relative amplitude thresholds of the temperature wave field and on the linear IGW saturation theory in which amplitude thresholds are restricted by dynamical (shear) instability processes in the atmosphere. When the amplitude of an internal gravity wave reaches the shear instability limit, energy is assumed to be dissipated in such a way that the amplitude is maintained at the instability limit as the wave propagates upwards. In order to approbate the method we have used data of simultaneous high-resolution balloon measurements of the temperature and wind velocity in the Earth's stratosphere over France where a long-period inertia-gravity wave has been detected. Using the radiosonde temperature data only, we have reconstructed all wave parameters, which were determined by radiosondes, with relative deviations not larger than 30 %. An application of the method to the radio occultation (RO) data has given the possibility to identify the IGWs in the Earth's stratosphere and to determine the magnitudes of key wave parameters such as the intrinsic frequency, Correspondence to: V. N. Gubenko (vngubenko@gmail.com) amplitudes of vertical and horizontal perturbations of the wind velocity, vertical and horizontal wavelengths, intrinsic vertical and horizontal phase (and group) speeds, kinetic and potential energy, vertical fluxes of the wave energy and horizontal momentum. The obtained results of internal wave studies in the Earth's stratosphere deduced from the COS-MIC and CHAMP GPS occultation temperature profiles are presented and discussed.
Abstract. By using the CHAllenge Minisatellite Payload (CHAMP) radio occultation (RO) data, a description of different types of the ionospheric impacts on the RO signals at the altitudes 30-90 km of the RO ray perigee is given and compared with the results of measurements obtained earlier in the satellite-to-Earth communication link at frequency 1.5415 GHz. An analytical model is introduced for describing propagation of radio waves in a stratified medium consisting of sectors with spherically symmetric refractivity distribution. This model gives analytical expressions for the phase, bending angle, and refractive attenuation of radio waves and is applied to the analysis of radio wave propagation phenomena along an extended path including the atmosphere and two parts of the ionosphere. The model explains significant amplitude and phase variations at altitudes 30-90 km of the RO ray perigee and attributes them to inclined ionospheric layers. Based on this analytical model, an innovative technique is introduced to locate layers in the atmosphere and ionosphere. A necessary and sufficient criterion is obtained for a layer to be located at the RO ray perigee. This criterion gives both qualitative and quantitative estimation of the displacement of an ionospheric and/or atmospheric layer from the RO ray perigee. This is important, in particular, for determining the location of wind shears and directions of the internal wave propagation in the lower ionosphere, and, possibly, in the atmosphere.
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