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[1] Exploitation of stellar scintillation allows studying air density irregularities in the stratosphere. In this paper, we develop a methodology for reconstruction of internal gravity wave (IGW) and turbulence parameters using scintillation measurements by the Global Ozone Monitoring by Occultation of Star (GOMOS) fast photometers on board the Envisat satellite. The forward model is based on a two-component spectral model of air density irregularities: the first component corresponds to the gravity wave spectrum, while the second one describes locally isotropic turbulence resulting from internal gravity wave breaking. The retrieval of parameters of IGW and turbulence spectra is based on the maximum likelihood method. The developed algorithm is tested on simulated and real data, and its accuracy is assessed. It is shown that the measured scintillation spectra are in good agreement with the proposed model and that structure characteristics and inner and outer scales of the anisotropic component can be reconstructed from scintillation spectra. The developed method can provide information about global distribution of parameters of IGW and turbulence spectra in the stratosphere at altitudes from 25 to 50 km.Citation: Sofieva, V. F., A. S. Gurvich, F. Dalaudier, and V. Kan (2007), Reconstruction of internal gravity wave and turbulence parameters in the stratosphere using GOMOS scintillation measurements,

A rigorous mathematical description is given for the physical concept of the cascade process of sequential breakdown of turbulent eddies. It is assumed that the probability distribution for the ratio of typical values of turbulent fluctuations averaged over a small volume v to those averaged over a surrounding larger volume V is invariant under the group of space similarity transformations, provided that the length scales of both volumes are much smaller than the external scale of turbulence and much larger than the Kolmogoroff scale. This assumption is in general agreement with the conclusions of Kolmogoroff and Obukhov and with the existing measurements of the power spectrum for the square of the velocity derivative. Some measurements of probability distributions for smallscale turbulent fluctuations are also discussed.

[1] Spatial spectra and characteristic scales of stratospheric density fluctuations obtained from the space station Mir observations of stellar scintillations are analyzed in this paper. The remote sensing method described is based on a well-known stellar scintillation phenomenon that arises when observing the stars through the Earth's atmosphere. To interpret scintillation spectra, a model of the three-dimensional (3-D) spectrum of atmospheric density fluctuations consisting of both turbulent and internal wave-associated spectral components is presented here. With the model chosen, we explain scintillation spectra at low frequencies by suggesting the atmospheric density fluctuations to be caused by a random ensemble of internal waves with the À5 power law decay for their 3-D energy spectrum. For the wave-associated anisotropic part of the spectrum, so-called outer and internal vertical scales are introduced to explain behavior of the observed scintillation spectra in their low-frequency range. These scales being earlier proposed only theoretically have been simultaneously revealed in the scintillation spectra presented here. The estimates of the outer scale for the different orbits of the space station are obtained and compared with those found from lidar and rocket soundings of the stratosphere. A possible cause of the observed variation in the wave number bandwidth of the waveassociated part of the spectrum of air density fluctuations is discussed.Citation: Gurvich, A., and I. Chunchuzov (2005), Estimates of characteristic scales in the spectrum of internal waves in the stratosphere obtained from space observations of stellar scintillations,

[1] Measurements of stellar scintillations caused by the atmosphere, conducted on board the space station Mir, are analyzed here. From scintillation spectra we obtained the parameters of spatial spectra of atmospheric density fluctuations (the altitudes 20-70 km) with vertical scales from hundreds of meters to tens of centimeters. The observed characteristic scales of atmospheric inhomogeneities are interpreted with a nonlinear model of internal wave spectrum and a theory of locally homogeneous and isotropic turbulence.