Ionospheric irregularities induced by the turbulence of the neutral atmosphere: possible deviation from isotropy

1Kyzyurov, Yu.V
1Main Astronomical Observatory of the National Academy of Sciences of Ukraine, Kyiv, Ukraine
Косм. наука технол. 2001, 7 ;(Suppl. 2):052-055
Мова публікації: англійська
The results of study of possible deviation of plasma irregularities caused by the action of neutral air turbulence in the lower ionosphere from isotropy are presented in this report. The consideration was based on an analytic expression for the three-dimensional (3D) spectrum of such irregularities. By integrating the 3D spectrum, ID spectra were derived for two different directions of its possible measurements. It was shown that the spectra of the irregularities are quite close to an isotropic one, although there are some their deviations from isotropy on the edges of the considered wave-number range. These deviations result from changes in a relative role of the geomagnetic field (more important for larger wave numbers) and the gradient of mean plasma density (more important for smaller ones) in creating the plasma irregularities of different scales. Estimations of slope of the irregularity spectra and of the root-mean-square level of plasma fluctuations were made too. There is good agreement between the obtained results and the data gathered during a rocket-radar simultaneous experiment in the lower ionosphere at high latitudes.
1. Gurevich A. V., Rinnert K., Schlegel K. Low frequency fluctuations in the lower E-region described by neutral turbulence. In: Schlegel K. (Ed.) Plasma Instabilities in the Ionospheric E-Region, 5—8 (Cuvillier Verlag, Gttingen, 1996).
2. Kyzyurov Yu. V., Malovichko P. P., Nosov S. F. Plasma irregularities in a turbulent flow of partially ionized gas. I. Spatial spectrum
of plasma density fluctuations in the lower Earth's ionosphere. Kinematika i Fizika Nebesnykh Tel15 (5), 455— 466 (1999) [in Russian].
3. Kyzyurov Yu. V., Malovichko P. P., Nosov S. F. Plasma irregularities in a turbulent flow of partially ionized gas. II. Feartures of spatial spectrum of plasma density fluctuations in the lower ionosphere. Kinematika i Fizika Nebesnykh Tel15 (5), 467—475 (1999) [in Russian].
4. Ovezgeldyev O. G., Karadzhaev Yu., Korsunova L. P. The amplitude spectrum of a radio signal reflected from the £s-layer. Geomagnetizm i Aeronomiia28 (6), 1024—1026 (1988) [in Russian].
5. Rose G., Schlegel K., Rinnert K., et al. The ROSE project. Scientific objectives and discussion of first results. J. Atmos. Terr. Phys., 54 (6), 657—667 (1992).
6. Ryrvic O., Smith L. G. Comparison of mesospheric VHF radar echoes and rocket probe electron concentration measurements. J. Geophys. Res., 89(A10), 9014—9022 (1984).
7. Schlegel K. Measurements of electron density fluctuations during the ROSE rocket flights. J. Atmos. Terr. Phys., 54 (6), 715—723 (1992).

8. Schlegel K., Gurevich A. V. Radar backscatter from plasma irregularities of the lower E-region induced by neutral turbulence. Ann. Geophysicae15(7), 870—877 (1997).